Search Results

Search found 5653 results on 227 pages for 'zero cool'.

Page 22/227 | < Previous Page | 18 19 20 21 22 23 24 25 26 27 28 29  | Next Page >

  • Can I mix compile time string comparison with MPL templates?

    - by Negative Zero
    I got this compile time string comparison from another thread using constexpr and C++11 (http://stackoverflow.com/questions/5721813/compile-time-assert-for-string-equality). It works with constant strings like "OK" constexpr bool isequal(char const *one, char const *two) { return (*one && *two) ? (*one == *two && isequal(one + 1, two + 1)) : (!*one && !*two); } I am trying to use it in the following context: static_assert(isequal(boost::mpl::c_str<boost::mpl::string<'ak'>>::value, "ak"), "should not fail"); But it gives me an compilation error of static_assert expression is not an constant integral expression. Can I do this?

    Read the article

  • Load local Html file doesn't refer the js file in UIWebView

    - by Hero Vs Zero
    I am working with UIWebView project and I want to load an HTML file from a project resource. It is working fine when I run from the URL, but when I view the HTML file locally, JS files are not loaded. Loading the local HTML local file doesn't refer to js files in UIWebView. Here's my code to load the HTML file project local resource and does't refer the js file: NSString *path = [[NSBundle mainBundle] pathForResource:@"textfile" ofType:@"txt"]; NSError *error = nil; NSString *string = [[NSString alloc] initWithContentsOfFile:path encoding:NSUTF8StringEncoding error:&error]; NSString *path1 = [[NSBundle mainBundle] bundlePath]; NSURL *baseURL = [NSURL fileURLWithPath:path1]; NSLog(@"%@ >>> %@",baseURL,path); [webview loadHTMLString:string baseURL:baseURL]; This code doesn't find JS files in UIWebView, even though it loads image files from the project resource successfully.

    Read the article

  • Running Javascript in PHP

    - by Zero
    I'm loading an external .php file using: <script type="text/javascript" src="myfile.js.php"></script> Within the external myfile.js.php file, I'm using: <?php header('content-type: text/javascript'); $message = "Test message"; ?> document.write('<?php echo $message; ?>'); Everything works fine until I change the name of myfile.js.php to just myfile.php Why does it stop working if I remove the .js part from the file name? I'm serving the file as text/javascript, plus shouldn't the .js part be ignored since .php is the actual file extension? Does anyone know why? Thanks!

    Read the article

  • Access the camera of a Smartphone using libGDX

    - by PH-zero
    I searched the web, browsed through the libGDX wiki, but without success. My Question: Is there a way, to access the camera of smartphones, let the user take a photo, and then store the image in a Texture-instance? I could imagin something like this: @Override public void onCamTrigger(){ ApplicationType appType = Gdx.app.getType(); switch (appType) { case Android: case iOS: Texture someTexture = new Texture(Gdx.input.getCamera().getImage()); //do something with the Texture instance... someTexture.dispose(); break; default: break; } } Of course this is pure fiction! I know that there's a lot more to this like opening the camera, displaying it, then take a photo etc. . But is there a convenience method like this? If so, how does it work? On Android, i think i could implement it without using any convenience methods offered by libGDX, but i have no idea on how this works on iOS =/

    Read the article

  • Creating a folder inside Mac OS App

    - by Negative Zero
    I want a an app that is "self-contained" (I don't know if i use the right word. "putting the app into trash bin will remove everything" is what I meant). But the app requires some resources to run. I usually put those resources into a folder. I want to move those resources into the App folder ( package contents). Can I do that? Is it a good practice to do that? When I test the app directly running from Xcode, the App runs fine. But if i run it from finder, the app will say fails to create resources folder because permission denied. I checked the app's folder permission - User(me) has read/write access. I am wondering what is causing this different behavior. The last option is to use Application Support folder, but I don't want to leave trails when user deletes the app. Can someone help me out here?

    Read the article

  • __declspec(dllimport) causes compiler crash on MSVC 2010

    - by Zero
    In a *.cpp file, trying to use a third party lib: #define DLL_IMPORT #include <thirdParty.h> // Third party header has code like: // #ifdef DLL_IMPORT // #define DLL_DECL __declspec(dllimport) // fatal error C1001: An internal error has occurred in the compiler. Alternative: #define NO_DLL #include <thirdParty.h> // Third party header has code like: // #elif defined(NO_DLL) // #define DLL_DECL // Compiles fine, but linker errors as can't find DLL functions // I can reproduce results by remove macros and #define all together and manually editing the third party files to have __declspec(dllimport) or not Has anyone come across anything similar, or can hint at the cause? (which is created using CMake). Above is actual example of 2 line *.cpp that crashes so it's narrowed down to something in the #include. The following also work fine: Compile the examples provided by the third party (they provide a *.sln) that use dllimport/export so it doesn't appear to be the fault of the library Compile the third party lib as part of the production project (so dllexport works fine) I've trawled the project settings pages of the two projects to try and spot differences, but have come up blank. Of course, it's possible I'm missing something as those settings pages are not the easiest to navigate. I'll get access to VS2008 in a day or so, so can compare with that. The third party library is MySql++.

    Read the article

  • destructor being called by subclass

    - by zero
    I'm currently learning more about php objects and constructors/destructors, but i've noticed in my code that the parent class's destructor is being called twice, I thought it was because i was extending the first class to my second class and that the second class was calling it, but this is what the php docs say about that: Like constructors, parent destructors will not be called implicitly by the engine. In order to run a parent destructor, one would have to explicitly call parent::__destruct() in the destructor body. so if it is not being called by the subclass then is it because by extended the first class that i've made a reference to the parent class making it call itself twice or I'm I way off base here? the code: <?php class test{ public $test1 = "this is a test of a pulic property"; private $test2 = "this is a test of a private property"; protected $test3 = "this is a test of a protected property"; const hello = 900000; function __construct($h){ //echo 'this is the constructor test '.$h; } function x($x2){ echo ' this is fn x'.$x2; } function y(){ print "this is fn y"; } } $obj = new test("this is an \"arg\" sent to instance of test"); class hey extends test{ function hey(){ $this->x('<br>from the host with the most'); echo ' <br>from hey class'.$this->test3; } } $obj2 = new hey(); echo $obj2::hello; ?>

    Read the article

  • Existing function to slice pandas object by axis number

    - by Zero
    Pandas has the following indexers: Object Type Indexers Series s.loc[indexer] DataFrame df.loc[row_indexer,column_indexer] Panel p.loc[item_indexer,major_indexer,minor_indexer] I would like to be able to index dynamically by axis, for example: df = pd.DataFrame(data=0, index=['row1', 'row2', 'row3'], columns=['col1', 'col2', col3']) df.index(['row1', 'row3'], axis=0) # index by rows df.index(['col1', 'col2'], axis=1) # index by columns Is there a built-in function that does this?

    Read the article

  • value types in the vm

    - by john.rose
    value types in the vm p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} p.p2 {margin: 0.0px 0.0px 14.0px 0.0px; font: 14.0px Times} p.p3 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times} p.p4 {margin: 0.0px 0.0px 15.0px 0.0px; font: 14.0px Times} p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier} p.p6 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier; min-height: 17.0px} p.p7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p8 {margin: 0.0px 0.0px 0.0px 36.0px; text-indent: -36.0px; font: 14.0px Times; min-height: 18.0px} p.p9 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p10 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; color: #000000} li.li1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} li.li7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} span.s1 {font: 14.0px Courier} span.s2 {color: #000000} span.s3 {font: 14.0px Courier; color: #000000} ol.ol1 {list-style-type: decimal} Or, enduring values for a changing world. Introduction A value type is a data type which, generally speaking, is designed for being passed by value in and out of methods, and stored by value in data structures. The only value types which the Java language directly supports are the eight primitive types. Java indirectly and approximately supports value types, if they are implemented in terms of classes. For example, both Integer and String may be viewed as value types, especially if their usage is restricted to avoid operations appropriate to Object. In this note, we propose a definition of value types in terms of a design pattern for Java classes, accompanied by a set of usage restrictions. We also sketch the relation of such value types to tuple types (which are a JVM-level notion), and point out JVM optimizations that can apply to value types. This note is a thought experiment to extend the JVM’s performance model in support of value types. The demonstration has two phases.  Initially the extension can simply use design patterns, within the current bytecode architecture, and in today’s Java language. But if the performance model is to be realized in practice, it will probably require new JVM bytecode features, changes to the Java language, or both.  We will look at a few possibilities for these new features. An Axiom of Value In the context of the JVM, a value type is a data type equipped with construction, assignment, and equality operations, and a set of typed components, such that, whenever two variables of the value type produce equal corresponding values for their components, the values of the two variables cannot be distinguished by any JVM operation. Here are some corollaries: A value type is immutable, since otherwise a copy could be constructed and the original could be modified in one of its components, allowing the copies to be distinguished. Changing the component of a value type requires construction of a new value. The equals and hashCode operations are strictly component-wise. If a value type is represented by a JVM reference, that reference cannot be successfully synchronized on, and cannot be usefully compared for reference equality. A value type can be viewed in terms of what it doesn’t do. We can say that a value type omits all value-unsafe operations, which could violate the constraints on value types.  These operations, which are ordinarily allowed for Java object types, are pointer equality comparison (the acmp instruction), synchronization (the monitor instructions), all the wait and notify methods of class Object, and non-trivial finalize methods. The clone method is also value-unsafe, although for value types it could be treated as the identity function. Finally, and most importantly, any side effect on an object (however visible) also counts as an value-unsafe operation. A value type may have methods, but such methods must not change the components of the value. It is reasonable and useful to define methods like toString, equals, and hashCode on value types, and also methods which are specifically valuable to users of the value type. Representations of Value Value types have two natural representations in the JVM, unboxed and boxed. An unboxed value consists of the components, as simple variables. For example, the complex number x=(1+2i), in rectangular coordinate form, may be represented in unboxed form by the following pair of variables: /*Complex x = Complex.valueOf(1.0, 2.0):*/ double x_re = 1.0, x_im = 2.0; These variables might be locals, parameters, or fields. Their association as components of a single value is not defined to the JVM. Here is a sample computation which computes the norm of the difference between two complex numbers: double distance(/*Complex x:*/ double x_re, double x_im,         /*Complex y:*/ double y_re, double y_im) {     /*Complex z = x.minus(y):*/     double z_re = x_re - y_re, z_im = x_im - y_im;     /*return z.abs():*/     return Math.sqrt(z_re*z_re + z_im*z_im); } A boxed representation groups component values under a single object reference. The reference is to a ‘wrapper class’ that carries the component values in its fields. (A primitive type can naturally be equated with a trivial value type with just one component of that type. In that view, the wrapper class Integer can serve as a boxed representation of value type int.) The unboxed representation of complex numbers is practical for many uses, but it fails to cover several major use cases: return values, array elements, and generic APIs. The two components of a complex number cannot be directly returned from a Java function, since Java does not support multiple return values. The same story applies to array elements: Java has no ’array of structs’ feature. (Double-length arrays are a possible workaround for complex numbers, but not for value types with heterogeneous components.) By generic APIs I mean both those which use generic types, like Arrays.asList and those which have special case support for primitive types, like String.valueOf and PrintStream.println. Those APIs do not support unboxed values, and offer some problems to boxed values. Any ’real’ JVM type should have a story for returns, arrays, and API interoperability. The basic problem here is that value types fall between primitive types and object types. Value types are clearly more complex than primitive types, and object types are slightly too complicated. Objects are a little bit dangerous to use as value carriers, since object references can be compared for pointer equality, and can be synchronized on. Also, as many Java programmers have observed, there is often a performance cost to using wrapper objects, even on modern JVMs. Even so, wrapper classes are a good starting point for talking about value types. If there were a set of structural rules and restrictions which would prevent value-unsafe operations on value types, wrapper classes would provide a good notation for defining value types. This note attempts to define such rules and restrictions. Let’s Start Coding Now it is time to look at some real code. Here is a definition, written in Java, of a complex number value type. @ValueSafe public final class Complex implements java.io.Serializable {     // immutable component structure:     public final double re, im;     private Complex(double re, double im) {         this.re = re; this.im = im;     }     // interoperability methods:     public String toString() { return "Complex("+re+","+im+")"; }     public List<Double> asList() { return Arrays.asList(re, im); }     public boolean equals(Complex c) {         return re == c.re && im == c.im;     }     public boolean equals(@ValueSafe Object x) {         return x instanceof Complex && equals((Complex) x);     }     public int hashCode() {         return 31*Double.valueOf(re).hashCode()                 + Double.valueOf(im).hashCode();     }     // factory methods:     public static Complex valueOf(double re, double im) {         return new Complex(re, im);     }     public Complex changeRe(double re2) { return valueOf(re2, im); }     public Complex changeIm(double im2) { return valueOf(re, im2); }     public static Complex cast(@ValueSafe Object x) {         return x == null ? ZERO : (Complex) x;     }     // utility methods and constants:     public Complex plus(Complex c)  { return new Complex(re+c.re, im+c.im); }     public Complex minus(Complex c) { return new Complex(re-c.re, im-c.im); }     public double abs() { return Math.sqrt(re*re + im*im); }     public static final Complex PI = valueOf(Math.PI, 0.0);     public static final Complex ZERO = valueOf(0.0, 0.0); } This is not a minimal definition, because it includes some utility methods and other optional parts.  The essential elements are as follows: The class is marked as a value type with an annotation. The class is final, because it does not make sense to create subclasses of value types. The fields of the class are all non-private and final.  (I.e., the type is immutable and structurally transparent.) From the supertype Object, all public non-final methods are overridden. The constructor is private. Beyond these bare essentials, we can observe the following features in this example, which are likely to be typical of all value types: One or more factory methods are responsible for value creation, including a component-wise valueOf method. There are utility methods for complex arithmetic and instance creation, such as plus and changeIm. There are static utility constants, such as PI. The type is serializable, using the default mechanisms. There are methods for converting to and from dynamically typed references, such as asList and cast. The Rules In order to use value types properly, the programmer must avoid value-unsafe operations.  A helpful Java compiler should issue errors (or at least warnings) for code which provably applies value-unsafe operations, and should issue warnings for code which might be correct but does not provably avoid value-unsafe operations.  No such compilers exist today, but to simplify our account here, we will pretend that they do exist. A value-safe type is any class, interface, or type parameter marked with the @ValueSafe annotation, or any subtype of a value-safe type.  If a value-safe class is marked final, it is in fact a value type.  All other value-safe classes must be abstract.  The non-static fields of a value class must be non-public and final, and all its constructors must be private. Under the above rules, a standard interface could be helpful to define value types like Complex.  Here is an example: @ValueSafe public interface ValueType extends java.io.Serializable {     // All methods listed here must get redefined.     // Definitions must be value-safe, which means     // they may depend on component values only.     List<? extends Object> asList();     int hashCode();     boolean equals(@ValueSafe Object c);     String toString(); } //@ValueSafe inherited from supertype: public final class Complex implements ValueType { … The main advantage of such a conventional interface is that (unlike an annotation) it is reified in the runtime type system.  It could appear as an element type or parameter bound, for facilities which are designed to work on value types only.  More broadly, it might assist the JVM to perform dynamic enforcement of the rules for value types. Besides types, the annotation @ValueSafe can mark fields, parameters, local variables, and methods.  (This is redundant when the type is also value-safe, but may be useful when the type is Object or another supertype of a value type.)  Working forward from these annotations, an expression E is defined as value-safe if it satisfies one or more of the following: The type of E is a value-safe type. E names a field, parameter, or local variable whose declaration is marked @ValueSafe. E is a call to a method whose declaration is marked @ValueSafe. E is an assignment to a value-safe variable, field reference, or array reference. E is a cast to a value-safe type from a value-safe expression. E is a conditional expression E0 ? E1 : E2, and both E1 and E2 are value-safe. Assignments to value-safe expressions and initializations of value-safe names must take their values from value-safe expressions. A value-safe expression may not be the subject of a value-unsafe operation.  In particular, it cannot be synchronized on, nor can it be compared with the “==” operator, not even with a null or with another value-safe type. In a program where all of these rules are followed, no value-type value will be subject to a value-unsafe operation.  Thus, the prime axiom of value types will be satisfied, that no two value type will be distinguishable as long as their component values are equal. More Code To illustrate these rules, here are some usage examples for Complex: Complex pi = Complex.valueOf(Math.PI, 0); Complex zero = pi.changeRe(0);  //zero = pi; zero.re = 0; ValueType vtype = pi; @SuppressWarnings("value-unsafe")   Object obj = pi; @ValueSafe Object obj2 = pi; obj2 = new Object();  // ok List<Complex> clist = new ArrayList<Complex>(); clist.add(pi);  // (ok assuming List.add param is @ValueSafe) List<ValueType> vlist = new ArrayList<ValueType>(); vlist.add(pi);  // (ok) List<Object> olist = new ArrayList<Object>(); olist.add(pi);  // warning: "value-unsafe" boolean z = pi.equals(zero); boolean z1 = (pi == zero);  // error: reference comparison on value type boolean z2 = (pi == null);  // error: reference comparison on value type boolean z3 = (pi == obj2);  // error: reference comparison on value type synchronized (pi) { }  // error: synch of value, unpredictable result synchronized (obj2) { }  // unpredictable result Complex qq = pi; qq = null;  // possible NPE; warning: “null-unsafe" qq = (Complex) obj;  // warning: “null-unsafe" qq = Complex.cast(obj);  // OK @SuppressWarnings("null-unsafe")   Complex empty = null;  // possible NPE qq = empty;  // possible NPE (null pollution) The Payoffs It follows from this that either the JVM or the java compiler can replace boxed value-type values with unboxed ones, without affecting normal computations.  Fields and variables of value types can be split into their unboxed components.  Non-static methods on value types can be transformed into static methods which take the components as value parameters. Some common questions arise around this point in any discussion of value types. Why burden the programmer with all these extra rules?  Why not detect programs automagically and perform unboxing transparently?  The answer is that it is easy to break the rules accidently unless they are agreed to by the programmer and enforced.  Automatic unboxing optimizations are tantalizing but (so far) unreachable ideal.  In the current state of the art, it is possible exhibit benchmarks in which automatic unboxing provides the desired effects, but it is not possible to provide a JVM with a performance model that assures the programmer when unboxing will occur.  This is why I’m writing this note, to enlist help from, and provide assurances to, the programmer.  Basically, I’m shooting for a good set of user-supplied “pragmas” to frame the desired optimization. Again, the important thing is that the unboxing must be done reliably, or else programmers will have no reason to work with the extra complexity of the value-safety rules.  There must be a reasonably stable performance model, wherein using a value type has approximately the same performance characteristics as writing the unboxed components as separate Java variables. There are some rough corners to the present scheme.  Since Java fields and array elements are initialized to null, value-type computations which incorporate uninitialized variables can produce null pointer exceptions.  One workaround for this is to require such variables to be null-tested, and the result replaced with a suitable all-zero value of the value type.  That is what the “cast” method does above. Generically typed APIs like List<T> will continue to manipulate boxed values always, at least until we figure out how to do reification of generic type instances.  Use of such APIs will elicit warnings until their type parameters (and/or relevant members) are annotated or typed as value-safe.  Retrofitting List<T> is likely to expose flaws in the present scheme, which we will need to engineer around.  Here are a couple of first approaches: public interface java.util.List<@ValueSafe T> extends Collection<T> { … public interface java.util.List<T extends Object|ValueType> extends Collection<T> { … (The second approach would require disjunctive types, in which value-safety is “contagious” from the constituent types.) With more transformations, the return value types of methods can also be unboxed.  This may require significant bytecode-level transformations, and would work best in the presence of a bytecode representation for multiple value groups, which I have proposed elsewhere under the title “Tuples in the VM”. But for starters, the JVM can apply this transformation under the covers, to internally compiled methods.  This would give a way to express multiple return values and structured return values, which is a significant pain-point for Java programmers, especially those who work with low-level structure types favored by modern vector and graphics processors.  The lack of multiple return values has a strong distorting effect on many Java APIs. Even if the JVM fails to unbox a value, there is still potential benefit to the value type.  Clustered computing systems something have copy operations (serialization or something similar) which apply implicitly to command operands.  When copying JVM objects, it is extremely helpful to know when an object’s identity is important or not.  If an object reference is a copied operand, the system may have to create a proxy handle which points back to the original object, so that side effects are visible.  Proxies must be managed carefully, and this can be expensive.  On the other hand, value types are exactly those types which a JVM can “copy and forget” with no downside. Array types are crucial to bulk data interfaces.  (As data sizes and rates increase, bulk data becomes more important than scalar data, so arrays are definitely accompanying us into the future of computing.)  Value types are very helpful for adding structure to bulk data, so a successful value type mechanism will make it easier for us to express richer forms of bulk data. Unboxing arrays (i.e., arrays containing unboxed values) will provide better cache and memory density, and more direct data movement within clustered or heterogeneous computing systems.  They require the deepest transformations, relative to today’s JVM.  There is an impedance mismatch between value-type arrays and Java’s covariant array typing, so compromises will need to be struck with existing Java semantics.  It is probably worth the effort, since arrays of unboxed value types are inherently more memory-efficient than standard Java arrays, which rely on dependent pointer chains. It may be sufficient to extend the “value-safe” concept to array declarations, and allow low-level transformations to change value-safe array declarations from the standard boxed form into an unboxed tuple-based form.  Such value-safe arrays would not be convertible to Object[] arrays.  Certain connection points, such as Arrays.copyOf and System.arraycopy might need additional input/output combinations, to allow smooth conversion between arrays with boxed and unboxed elements. Alternatively, the correct solution may have to wait until we have enough reification of generic types, and enough operator overloading, to enable an overhaul of Java arrays. Implicit Method Definitions The example of class Complex above may be unattractively complex.  I believe most or all of the elements of the example class are required by the logic of value types. If this is true, a programmer who writes a value type will have to write lots of error-prone boilerplate code.  On the other hand, I think nearly all of the code (except for the domain-specific parts like plus and minus) can be implicitly generated. Java has a rule for implicitly defining a class’s constructor, if no it defines no constructors explicitly.  Likewise, there are rules for providing default access modifiers for interface members.  Because of the highly regular structure of value types, it might be reasonable to perform similar implicit transformations on value types.  Here’s an example of a “highly implicit” definition of a complex number type: public class Complex implements ValueType {  // implicitly final     public double re, im;  // implicitly public final     //implicit methods are defined elementwise from te fields:     //  toString, asList, equals(2), hashCode, valueOf, cast     //optionally, explicit methods (plus, abs, etc.) would go here } In other words, with the right defaults, a simple value type definition can be a one-liner.  The observant reader will have noticed the similarities (and suitable differences) between the explicit methods above and the corresponding methods for List<T>. Another way to abbreviate such a class would be to make an annotation the primary trigger of the functionality, and to add the interface(s) implicitly: public @ValueType class Complex { … // implicitly final, implements ValueType (But to me it seems better to communicate the “magic” via an interface, even if it is rooted in an annotation.) Implicitly Defined Value Types So far we have been working with nominal value types, which is to say that the sequence of typed components is associated with a name and additional methods that convey the intention of the programmer.  A simple ordered pair of floating point numbers can be variously interpreted as (to name a few possibilities) a rectangular or polar complex number or Cartesian point.  The name and the methods convey the intended meaning. But what if we need a truly simple ordered pair of floating point numbers, without any further conceptual baggage?  Perhaps we are writing a method (like “divideAndRemainder”) which naturally returns a pair of numbers instead of a single number.  Wrapping the pair of numbers in a nominal type (like “QuotientAndRemainder”) makes as little sense as wrapping a single return value in a nominal type (like “Quotient”).  What we need here are structural value types commonly known as tuples. For the present discussion, let us assign a conventional, JVM-friendly name to tuples, roughly as follows: public class java.lang.tuple.$DD extends java.lang.tuple.Tuple {      double $1, $2; } Here the component names are fixed and all the required methods are defined implicitly.  The supertype is an abstract class which has suitable shared declarations.  The name itself mentions a JVM-style method parameter descriptor, which may be “cracked” to determine the number and types of the component fields. The odd thing about such a tuple type (and structural types in general) is it must be instantiated lazily, in response to linkage requests from one or more classes that need it.  The JVM and/or its class loaders must be prepared to spin a tuple type on demand, given a simple name reference, $xyz, where the xyz is cracked into a series of component types.  (Specifics of naming and name mangling need some tasteful engineering.) Tuples also seem to demand, even more than nominal types, some support from the language.  (This is probably because notations for non-nominal types work best as combinations of punctuation and type names, rather than named constructors like Function3 or Tuple2.)  At a minimum, languages with tuples usually (I think) have some sort of simple bracket notation for creating tuples, and a corresponding pattern-matching syntax (or “destructuring bind”) for taking tuples apart, at least when they are parameter lists.  Designing such a syntax is no simple thing, because it ought to play well with nominal value types, and also with pre-existing Java features, such as method parameter lists, implicit conversions, generic types, and reflection.  That is a task for another day. Other Use Cases Besides complex numbers and simple tuples there are many use cases for value types.  Many tuple-like types have natural value-type representations. These include rational numbers, point locations and pixel colors, and various kinds of dates and addresses. Other types have a variable-length ‘tail’ of internal values. The most common example of this is String, which is (mathematically) a sequence of UTF-16 character values. Similarly, bit vectors, multiple-precision numbers, and polynomials are composed of sequences of values. Such types include, in their representation, a reference to a variable-sized data structure (often an array) which (somehow) represents the sequence of values. The value type may also include ’header’ information. Variable-sized values often have a length distribution which favors short lengths. In that case, the design of the value type can make the first few values in the sequence be direct ’header’ fields of the value type. In the common case where the header is enough to represent the whole value, the tail can be a shared null value, or even just a null reference. Note that the tail need not be an immutable object, as long as the header type encapsulates it well enough. This is the case with String, where the tail is a mutable (but never mutated) character array. Field types and their order must be a globally visible part of the API.  The structure of the value type must be transparent enough to have a globally consistent unboxed representation, so that all callers and callees agree about the type and order of components  that appear as parameters, return types, and array elements.  This is a trade-off between efficiency and encapsulation, which is forced on us when we remove an indirection enjoyed by boxed representations.  A JVM-only transformation would not care about such visibility, but a bytecode transformation would need to take care that (say) the components of complex numbers would not get swapped after a redefinition of Complex and a partial recompile.  Perhaps constant pool references to value types need to declare the field order as assumed by each API user. This brings up the delicate status of private fields in a value type.  It must always be possible to load, store, and copy value types as coordinated groups, and the JVM performs those movements by moving individual scalar values between locals and stack.  If a component field is not public, what is to prevent hostile code from plucking it out of the tuple using a rogue aload or astore instruction?  Nothing but the verifier, so we may need to give it more smarts, so that it treats value types as inseparable groups of stack slots or locals (something like long or double). My initial thought was to make the fields always public, which would make the security problem moot.  But public is not always the right answer; consider the case of String, where the underlying mutable character array must be encapsulated to prevent security holes.  I believe we can win back both sides of the tradeoff, by training the verifier never to split up the components in an unboxed value.  Just as the verifier encapsulates the two halves of a 64-bit primitive, it can encapsulate the the header and body of an unboxed String, so that no code other than that of class String itself can take apart the values. Similar to String, we could build an efficient multi-precision decimal type along these lines: public final class DecimalValue extends ValueType {     protected final long header;     protected private final BigInteger digits;     public DecimalValue valueOf(int value, int scale) {         assert(scale >= 0);         return new DecimalValue(((long)value << 32) + scale, null);     }     public DecimalValue valueOf(long value, int scale) {         if (value == (int) value)             return valueOf((int)value, scale);         return new DecimalValue(-scale, new BigInteger(value));     } } Values of this type would be passed between methods as two machine words. Small values (those with a significand which fits into 32 bits) would be represented without any heap data at all, unless the DecimalValue itself were boxed. (Note the tension between encapsulation and unboxing in this case.  It would be better if the header and digits fields were private, but depending on where the unboxing information must “leak”, it is probably safer to make a public revelation of the internal structure.) Note that, although an array of Complex can be faked with a double-length array of double, there is no easy way to fake an array of unboxed DecimalValues.  (Either an array of boxed values or a transposed pair of homogeneous arrays would be reasonable fallbacks, in a current JVM.)  Getting the full benefit of unboxing and arrays will require some new JVM magic. Although the JVM emphasizes portability, system dependent code will benefit from using machine-level types larger than 64 bits.  For example, the back end of a linear algebra package might benefit from value types like Float4 which map to stock vector types.  This is probably only worthwhile if the unboxing arrays can be packed with such values. More Daydreams A more finely-divided design for dynamic enforcement of value safety could feature separate marker interfaces for each invariant.  An empty marker interface Unsynchronizable could cause suitable exceptions for monitor instructions on objects in marked classes.  More radically, a Interchangeable marker interface could cause JVM primitives that are sensitive to object identity to raise exceptions; the strangest result would be that the acmp instruction would have to be specified as raising an exception. @ValueSafe public interface ValueType extends java.io.Serializable,         Unsynchronizable, Interchangeable { … public class Complex implements ValueType {     // inherits Serializable, Unsynchronizable, Interchangeable, @ValueSafe     … It seems possible that Integer and the other wrapper types could be retro-fitted as value-safe types.  This is a major change, since wrapper objects would be unsynchronizable and their references interchangeable.  It is likely that code which violates value-safety for wrapper types exists but is uncommon.  It is less plausible to retro-fit String, since the prominent operation String.intern is often used with value-unsafe code. We should also reconsider the distinction between boxed and unboxed values in code.  The design presented above obscures that distinction.  As another thought experiment, we could imagine making a first class distinction in the type system between boxed and unboxed representations.  Since only primitive types are named with a lower-case initial letter, we could define that the capitalized version of a value type name always refers to the boxed representation, while the initial lower-case variant always refers to boxed.  For example: complex pi = complex.valueOf(Math.PI, 0); Complex boxPi = pi;  // convert to boxed myList.add(boxPi); complex z = myList.get(0);  // unbox Such a convention could perhaps absorb the current difference between int and Integer, double and Double. It might also allow the programmer to express a helpful distinction among array types. As said above, array types are crucial to bulk data interfaces, but are limited in the JVM.  Extending arrays beyond the present limitations is worth thinking about; for example, the Maxine JVM implementation has a hybrid object/array type.  Something like this which can also accommodate value type components seems worthwhile.  On the other hand, does it make sense for value types to contain short arrays?  And why should random-access arrays be the end of our design process, when bulk data is often sequentially accessed, and it might make sense to have heterogeneous streams of data as the natural “jumbo” data structure.  These considerations must wait for another day and another note. More Work It seems to me that a good sequence for introducing such value types would be as follows: Add the value-safety restrictions to an experimental version of javac. Code some sample applications with value types, including Complex and DecimalValue. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. A staggered roll-out like this would decouple language changes from bytecode changes, which is always a convenient thing. A similar investigation should be applied (concurrently) to array types.  In this case, it seems to me that the starting point is in the JVM: Add an experimental unboxing array data structure to a production JVM, perhaps along the lines of Maxine hybrids.  No bytecode or language support is required at first; everything can be done with encapsulated unsafe operations and/or method handles. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. That’s enough musing me for now.  Back to work!

    Read the article

  • Somebody knows why the sectors of the IBM floppy disk are named 1 to 8 (and not 0 to 7 )

    - by Olivier Briand
    I am now programming on a 8 bits Z80 computer with CP/M 2.2, (as a hobby) and the floppy disk format is IBM, 40 tracks, 8 sectors per track, 512 bytes per sector. free space is 154 Ko on each face of the disk. Why the sectors are indexed 1 to 8 (and not zero to seven, as usually is seen with computers)? The catalog of the floppy disk is on the track 1 (sector 1 to 4, 64 entries). I'm wondering is the catalog on track zero? Is the zero track reserved to included a system (as track 0 & 1 are reserved to the system on a CP/M floppy disk, and catalog is on track 2)?

    Read the article

  • How to convert ISampleGrabber::BufferCB's buffer to a bitmap

    - by user2509919
    I am trying to use the ISampleGrabberCB::BufferCB to convert the current frame to bitmap using the following code: int ISampleGrabberCB.BufferCB(double sampleTime, IntPtr buffer, int bufferLength) { try { Form1 form1 = new Form1("", "", ""); if (pictureReady == null) { Debug.Assert(bufferLength == Math.Abs(pitch) * videoHeight, "Wrong Buffer Length"); } Debug.Assert(imageBuffer != IntPtr.Zero, "Remove Buffer"); Bitmap bitmapOfCurrentFrame = new Bitmap(width, height, capturePitch, PixelFormat.Format24bppRgb, buffer); MessageBox.Show("Works"); form1.changepicturebox3(bitmapOfCurrentFrame); pictureReady.Set(); } catch (Exception ex) { MessageBox.Show(ex.ToString()); } return 0; } However this does not seem to be working. Additionally it seems to call this function when i press a button which runs the following code: public IntPtr getFrame() { int hr; try { pictureReady.Reset(); } catch (Exception ex) { MessageBox.Show(ex.ToString()); } imageBuffer = Marshal.AllocCoTaskMem(Math.Abs(pitch) * videoHeight); try { gotFrame = true; if (videoControl != null) { hr = videoControl.SetMode(stillPin, VideoControlFlags.Trigger); DsError.ThrowExceptionForHR(hr); } if (!pictureReady.WaitOne(9000, false)) { throw new Exception("Timeout waiting to get picture"); } } catch { Marshal.FreeCoTaskMem(imageBuffer); imageBuffer = IntPtr.Zero; } return imageBuffer; } Once this code is ran I get a message box which shows 'Works' thus meaning my BufferCB must of been called however does not update my picture box with the current image. Is the BufferCB not called after every new frame? If so why do I not recieve the 'Works' message box? Finally is it possible to convert every new frame into a bitmap (this is used for later processing) using BufferCB and if so how? Edited code: int ISampleGrabberCB.BufferCB(double sampleTime, IntPtr buffer, int bufferLength) { Debug.Assert(bufferLength == Math.Abs(pitch) * videoHeight, "Wrong Buffer Length"); Debug.Assert(imageBuffer != IntPtr.Zero, "Remove Buffer"); CopyMemory(imageBuffer, buffer, bufferLength); Decode(buffer); return 0; } public Image Decode(IntPtr imageData) { var bitmap = new Bitmap(width, height, pitch, PixelFormat.Format24bppRgb, imageBuffer); bitmap.RotateFlip(RotateFlipType.RotateNoneFlipY); Form1 form1 = new Form1("", "", ""); form1.changepicturebox3(bitmap); bitmap.Save("C:\\Users\\...\\Desktop\\A2 Project\\barcode.jpg"); return bitmap; } Button code: public void getFrameFromWebcam() { if (iPtr != IntPtr.Zero) { Marshal.FreeCoTaskMem(iPtr); iPtr = IntPtr.Zero; } //Get Image iPtr = sampleGrabberCallBack.getFrame(); Bitmap bitmapOfFrame = new Bitmap(sampleGrabberCallBack.width, sampleGrabberCallBack.height, sampleGrabberCallBack.capturePitch, PixelFormat.Format24bppRgb, iPtr); bitmapOfFrame.RotateFlip(RotateFlipType.RotateNoneFlipY); barcodeReader(bitmapOfFrame); } public IntPtr getFrame() { int hr; try { pictureReady.Reset(); } catch (Exception ex) { MessageBox.Show(ex.ToString()); } imageBuffer = Marshal.AllocCoTaskMem(Math.Abs(pitch) * videoHeight); try { gotFrame = true; if (videoControl != null) { hr = videoControl.SetMode(stillPin, VideoControlFlags.Trigger); DsError.ThrowExceptionForHR(hr); } if (!pictureReady.WaitOne(9000, false)) { throw new Exception("Timeout waiting to get picture"); } } catch { Marshal.FreeCoTaskMem(imageBuffer); imageBuffer = IntPtr.Zero; } return imageBuffer; } I also still need to press the button to run the BufferCB Thanks for reading.

    Read the article

  • Defining recursive algebraic data types in XML XSD

    - by Ben Challenor
    Imagine I have a recursive algebraic data type like this (Haskell syntax): data Expr = Zero | One | Add Expr Expr | Mul Expr Expr I'd like to represent this in XML, and I'd like an XSD schema for it. I have figured out how to achieve this syntax: <Expr> <Add> <Expr> <Zero/> </Expr> <Expr> <Mul> <Expr> <One/> </Expr> <Expr> <Add> <Expr> <One/> </Expr> <Expr> <One/> </Expr> </Add> </Expr> </Mul> </Expr> </Add> </Expr> with this schema: <xs:complexType name="Expr"> <xs:choice minOccurs="1" maxOccurs="1"> <xs:element minOccurs="1" maxOccurs="1" name="Zero" type="Zero" /> <xs:element minOccurs="1" maxOccurs="1" name="One" type="One" /> <xs:element minOccurs="1" maxOccurs="1" name="Add" type="Add" /> <xs:element minOccurs="1" maxOccurs="1" name="Mul" type="Mul" /> </xs:choice> </xs:complexType> <xs:complexType name="Zero"> <xs:sequence> </xs:sequence> </xs:complexType> <xs:complexType name="One"> <xs:sequence> </xs:sequence> </xs:complexType> <xs:complexType name="Add"> <xs:sequence> <xs:element minOccurs="2" maxOccurs="2" name="Expr" type="Expr" /> </xs:sequence> </xs:complexType> <xs:complexType name="Mul"> <xs:sequence> <xs:element minOccurs="2" maxOccurs="2" name="Expr" type="Expr" /> </xs:sequence> </xs:complexType> But what I really want is this syntax: <Add> <Zero/> <Mul> <One/> <Add> <One/> <One/> </Add> </Mul> </Add> Is this possible? Thanks!

    Read the article

  • Desktop Customization: Sci-Fi Icon Packs

    - by Asian Angel
    Are you a sci-fi fan who has been looking for some great custom icons for your desktop or favorite app launcher? Then you will want to have a look through our sci-fi icon packs collection. Over the past few months we’ve been showing you collections of cool desktop wallpapers you can use to liven up your computer. Today we extend the customization collections with a series of cool icon packs for you to use for folders and shortcut icons. Star Wars 1.0 Download Star Wars the Icons Download Star Wars Vehicles Download Star Wars Icons Download Star Trek Download Trek Tech Note: Contains “.png files” for use in Linux. Download Refresh Trek Download Star Trek Folders Download Battlestar Galactica Vol. 1 Download Battlestar Galactica Vol. 2 Download Battlestar Galactica Vol. 3 Download Battlestar Galactica Vol. 4 Download Baby Spaceships Download Space: 1999 Download War of the Worlds   Download Conclusion Now that you have some of these cool icons downloaded, be sure to check out our tutorial on how to customize your icons in Vista and Windows 7. If you’re still using XP check out our article on customizing icons in Windows XP. Also, be you might want to visit our new Desktop Fun section for more customization goodness! Similar Articles Productive Geek Tips Restore Missing Desktop Icons in Windows 7 or VistaWindows 7 Welcome Screen Taking Forever? Here’s the Fix (Maybe)Add Home Directory Icon to the Desktop in Windows 7 or VistaQuick Help: Downloadable Show Desktop Icon for XPDisplay My Computer Icon on the Desktop in Windows 7 or Vista TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 PCmover Professional Windows 7 Easter Theme YoWindoW, a real time weather screensaver Optimize your computer the Microsoft way Stormpulse provides slick, real time weather data Geek Parents – Did you try Parental Controls in Windows 7? Change DNS servers on the fly with DNS Jumper

    Read the article

  • SQL SERVER – Removing Leading Zeros From Column in Table

    - by pinaldave
    Some questions surprises me and make me write code which I have never explored before. Today was similar experience as well. I have always received the question regarding how to reserve leading zeroes in SQL Server while displaying them on the SSMS or another application. I have written articles on this subject over here. SQL SERVER – Pad Ride Side of Number with 0 – Fixed Width Number Display SQL SERVER – UDF – Pad Ride Side of Number with 0 – Fixed Width Number Display SQL SERVER – Preserve Leading Zero While Coping to Excel from SSMS Today I received a very different question where the user wanted to remove leading zero and white space. I am using the same sample sent by user in this example. USE tempdb GO -- Create sample table CREATE TABLE Table1 (Col1 VARCHAR(100)) INSERT INTO Table1 (Col1) SELECT '0001' UNION ALL SELECT '000100' UNION ALL SELECT '100100' UNION ALL SELECT '000 0001' UNION ALL SELECT '00.001' UNION ALL SELECT '01.001' GO -- Original data SELECT * FROM Table1 GO -- Remove leading zeros SELECT SUBSTRING(Col1, PATINDEX('%[^0 ]%', Col1 + ' '), LEN(Col1)) FROM Table1 GO -- Clean up DROP TABLE Table1 GO Here is the resultset of above script. It will remove any leading zero or space and will display the number accordingly. This problem is a very generic problem and I am confident there are alternate solutions to this problem as well. If you have an alternate solution or can suggest a sample data which does not satisfy the SUBSTRING solution proposed, I will be glad to include them in follow up blog post with due credit. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

    Read the article

  • Ogre 3d and bullet physics interaction

    - by Tim
    I have been playing around with Ogre3d and trying to integrate bullet physics. I have previously somewhat successfully got this functionality working with irrlicht and bullet and I am trying to base this on what I had done there, but modifying it to fit with Ogre. It is working but not correctly and I would like some help to understand what it is I am doing wrong. I have a state system and when I enter the "gamestate" I call some functions such as setting up a basic scene, creating the physics simulation. I am doing that as follows. void GameState::enter() { ... // Setup Physics btBroadphaseInterface *BroadPhase = new btAxisSweep3(btVector3(-1000,-1000,-1000), btVector3(1000,1000,1000)); btDefaultCollisionConfiguration *CollisionConfiguration = new btDefaultCollisionConfiguration(); btCollisionDispatcher *Dispatcher = new btCollisionDispatcher(CollisionConfiguration); btSequentialImpulseConstraintSolver *Solver = new btSequentialImpulseConstraintSolver(); World = new btDiscreteDynamicsWorld(Dispatcher, BroadPhase, Solver, CollisionConfiguration); ... createScene(); } In the createScene method I add a light and try to setup a "ground" plane to act as the ground for things to collide with.. as follows. I expect there is issues with this as I get objects colliding with the ground but half way through it and they glitch around like crazy on collision. void GameState::createScene() { m_pSceneMgr->createLight("Light")->setPosition(75,75,75); // Physics // As a test we want a floor plane for things to collide with Ogre::Entity *ent; Ogre::Plane p; p.normal = Ogre::Vector3(0,1,0); p.d = 0; Ogre::MeshManager::getSingleton().createPlane( "FloorPlane", Ogre::ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME, p, 200000, 200000, 20, 20, true, 1, 9000,9000,Ogre::Vector3::UNIT_Z); ent = m_pSceneMgr->createEntity("floor", "FloorPlane"); ent->setMaterialName("Test/Floor"); Ogre::SceneNode *node = m_pSceneMgr->getRootSceneNode()->createChildSceneNode(); node->attachObject(ent); btTransform Transform; Transform.setIdentity(); Transform.setOrigin(btVector3(0,1,0)); // Give it to the motion state btDefaultMotionState *MotionState = new btDefaultMotionState(Transform); btCollisionShape *Shape = new btStaticPlaneShape(btVector3(0,1,0),0); // Add Mass btVector3 LocalInertia; Shape->calculateLocalInertia(0, LocalInertia); // CReate the rigid body object btRigidBody *RigidBody = new btRigidBody(0, MotionState, Shape, LocalInertia); // Store a pointer to the Ogre Node so we can update it later RigidBody->setUserPointer((void *) (node)); // Add it to the physics world World->addRigidBody(RigidBody); Objects.push_back(RigidBody); m_pNumEntities++; // End Physics } I then have a method to create a cube and give it rigid body physics properties. I know there will be errors here as I get the items colliding with the ground but not with each other properly. So I would appreciate some input on what I am doing wrong. void GameState::CreateBox(const btVector3 &TPosition, const btVector3 &TScale, btScalar TMass) { Ogre::Vector3 size = Ogre::Vector3::ZERO; Ogre::Vector3 pos = Ogre::Vector3::ZERO; Ogre::Vector3 scale = Ogre::Vector3::ZERO; pos.x = TPosition.getX(); pos.y = TPosition.getY(); pos.z = TPosition.getZ(); scale.x = TScale.getX(); scale.y = TScale.getY(); scale.z = TScale.getZ(); Ogre::Entity *entity = m_pSceneMgr->createEntity( "Box" + Ogre::StringConverter::toString(m_pNumEntities), "cube.mesh"); entity->setCastShadows(true); Ogre::AxisAlignedBox boundingB = entity->getBoundingBox(); size = boundingB.getSize(); //size /= 2.0f; // Only the half needed? //size *= 0.96f; // Bullet margin is a bit bigger so we need a smaller size entity->setMaterialName("Test/Cube"); Ogre::SceneNode *node = m_pSceneMgr->getRootSceneNode()->createChildSceneNode(); node->attachObject(entity); node->setPosition(pos); //node->scale(scale); // Physics btTransform Transform; Transform.setIdentity(); Transform.setOrigin(TPosition); // Give it to the motion state btDefaultMotionState *MotionState = new btDefaultMotionState(Transform); btVector3 HalfExtents(TScale.getX()*0.5f,TScale.getY()*0.5f,TScale.getZ()*0.5f); btCollisionShape *Shape = new btBoxShape(HalfExtents); // Add Mass btVector3 LocalInertia; Shape->calculateLocalInertia(TMass, LocalInertia); // CReate the rigid body object btRigidBody *RigidBody = new btRigidBody(TMass, MotionState, Shape, LocalInertia); // Store a pointer to the Ogre Node so we can update it later RigidBody->setUserPointer((void *) (node)); // Add it to the physics world World->addRigidBody(RigidBody); Objects.push_back(RigidBody); m_pNumEntities++; } Then in the GameState::update() method which which runs every frame to handle input and render etc I call an UpdatePhysics method to update the physics simulation. void GameState::UpdatePhysics(unsigned int TDeltaTime) { World->stepSimulation(TDeltaTime * 0.001f, 60); btRigidBody *TObject; for(std::vector<btRigidBody *>::iterator it = Objects.begin(); it != Objects.end(); ++it) { // Update renderer Ogre::SceneNode *node = static_cast<Ogre::SceneNode *>((*it)->getUserPointer()); TObject = *it; // Set position btVector3 Point = TObject->getCenterOfMassPosition(); node->setPosition(Ogre::Vector3((float)Point[0], (float)Point[1], (float)Point[2])); // set rotation btVector3 EulerRotation; QuaternionToEuler(TObject->getOrientation(), EulerRotation); node->setOrientation(1,(Ogre::Real)EulerRotation[0], (Ogre::Real)EulerRotation[1], (Ogre::Real)EulerRotation[2]); //node->rotate(Ogre::Vector3(EulerRotation[0], EulerRotation[1], EulerRotation[2])); } } void GameState::QuaternionToEuler(const btQuaternion &TQuat, btVector3 &TEuler) { btScalar W = TQuat.getW(); btScalar X = TQuat.getX(); btScalar Y = TQuat.getY(); btScalar Z = TQuat.getZ(); float WSquared = W * W; float XSquared = X * X; float YSquared = Y * Y; float ZSquared = Z * Z; TEuler.setX(atan2f(2.0f * (Y * Z + X * W), -XSquared - YSquared + ZSquared + WSquared)); TEuler.setY(asinf(-2.0f * (X * Z - Y * W))); TEuler.setZ(atan2f(2.0f * (X * Y + Z * W), XSquared - YSquared - ZSquared + WSquared)); TEuler *= RADTODEG; } I seem to have issues with the cubes not colliding with each other and colliding strangely with the ground. I have tried to capture the effect with the attached image. I would appreciate any help in understanding what I have done wrong. Thanks. EDIT : Solution The following code shows the changes I made to get accurate physics. void GameState::createScene() { m_pSceneMgr->createLight("Light")->setPosition(75,75,75); // Physics // As a test we want a floor plane for things to collide with Ogre::Entity *ent; Ogre::Plane p; p.normal = Ogre::Vector3(0,1,0); p.d = 0; Ogre::MeshManager::getSingleton().createPlane( "FloorPlane", Ogre::ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME, p, 200000, 200000, 20, 20, true, 1, 9000,9000,Ogre::Vector3::UNIT_Z); ent = m_pSceneMgr->createEntity("floor", "FloorPlane"); ent->setMaterialName("Test/Floor"); Ogre::SceneNode *node = m_pSceneMgr->getRootSceneNode()->createChildSceneNode(); node->attachObject(ent); btTransform Transform; Transform.setIdentity(); // Fixed the transform vector here for y back to 0 to stop the objects sinking into the ground. Transform.setOrigin(btVector3(0,0,0)); // Give it to the motion state btDefaultMotionState *MotionState = new btDefaultMotionState(Transform); btCollisionShape *Shape = new btStaticPlaneShape(btVector3(0,1,0),0); // Add Mass btVector3 LocalInertia; Shape->calculateLocalInertia(0, LocalInertia); // CReate the rigid body object btRigidBody *RigidBody = new btRigidBody(0, MotionState, Shape, LocalInertia); // Store a pointer to the Ogre Node so we can update it later RigidBody->setUserPointer((void *) (node)); // Add it to the physics world World->addRigidBody(RigidBody); Objects.push_back(RigidBody); m_pNumEntities++; // End Physics } void GameState::CreateBox(const btVector3 &TPosition, const btVector3 &TScale, btScalar TMass) { Ogre::Vector3 size = Ogre::Vector3::ZERO; Ogre::Vector3 pos = Ogre::Vector3::ZERO; Ogre::Vector3 scale = Ogre::Vector3::ZERO; pos.x = TPosition.getX(); pos.y = TPosition.getY(); pos.z = TPosition.getZ(); scale.x = TScale.getX(); scale.y = TScale.getY(); scale.z = TScale.getZ(); Ogre::Entity *entity = m_pSceneMgr->createEntity( "Box" + Ogre::StringConverter::toString(m_pNumEntities), "cube.mesh"); entity->setCastShadows(true); Ogre::AxisAlignedBox boundingB = entity->getBoundingBox(); // The ogre bounding box is slightly bigger so I am reducing it for // use with the rigid body. size = boundingB.getSize()*0.95f; entity->setMaterialName("Test/Cube"); Ogre::SceneNode *node = m_pSceneMgr->getRootSceneNode()->createChildSceneNode(); node->attachObject(entity); node->setPosition(pos); node->showBoundingBox(true); //node->scale(scale); // Physics btTransform Transform; Transform.setIdentity(); Transform.setOrigin(TPosition); // Give it to the motion state btDefaultMotionState *MotionState = new btDefaultMotionState(Transform); // I got the size of the bounding box above but wasn't using it to set // the size for the rigid body. This now does. btVector3 HalfExtents(size.x*0.5f,size.y*0.5f,size.z*0.5f); btCollisionShape *Shape = new btBoxShape(HalfExtents); // Add Mass btVector3 LocalInertia; Shape->calculateLocalInertia(TMass, LocalInertia); // CReate the rigid body object btRigidBody *RigidBody = new btRigidBody(TMass, MotionState, Shape, LocalInertia); // Store a pointer to the Ogre Node so we can update it later RigidBody->setUserPointer((void *) (node)); // Add it to the physics world World->addRigidBody(RigidBody); Objects.push_back(RigidBody); m_pNumEntities++; } void GameState::UpdatePhysics(unsigned int TDeltaTime) { World->stepSimulation(TDeltaTime * 0.001f, 60); btRigidBody *TObject; for(std::vector<btRigidBody *>::iterator it = Objects.begin(); it != Objects.end(); ++it) { // Update renderer Ogre::SceneNode *node = static_cast<Ogre::SceneNode *>((*it)->getUserPointer()); TObject = *it; // Set position btVector3 Point = TObject->getCenterOfMassPosition(); node->setPosition(Ogre::Vector3((float)Point[0], (float)Point[1], (float)Point[2])); // Convert the bullet Quaternion to an Ogre quaternion btQuaternion btq = TObject->getOrientation(); Ogre::Quaternion quart = Ogre::Quaternion(btq.w(),btq.x(),btq.y(),btq.z()); // use the quaternion with setOrientation node->setOrientation(quart); } } The QuaternionToEuler function isn't needed so that was removed from code and header files. The objects now collide with the ground and each other appropriately.

    Read the article

  • iPhone/iPad: Get Alerts When Paid Apps Go Free

    - by Gopinath
    iPhone users has thousands of cool applications to choose. These apps are either paid or absolutely free. Many of the paid applications goes free for either a limited time or forever depending on the mood of their developers. Will it not be cool to get alerts whenever a paid app goes free? Yeah, it will be great. Free App Alert is a handy website that checks iTunes store regularly and sends alerts to it’s subscribers about the apps that have gone from paid to free. You can receive the alerts by following them on twitter, facebook or subscribing to the traditional RSS feeds(yeah RSS is a traditional technology). The home page of this website shows the apps that have gone free today and you can browse through the previous day free apps listing with the help of links available at the bottom. Free App Alert is definitely a cool site to check out for iPhone/iPod/iPad users and certainly easier than scrolling through iTunes store and checking prices. Tip: Immediately download the app that have gone from paid to free as many apps are free for limited time. You can see many free apps going back to paid version if you go through the previous pages the website. Join us on Facebook to read all our stories right inside your Facebook news feed.

    Read the article

  • Stencil mask with AlphaTestEffect

    - by Brendan Wanlass
    I am trying to pull off the following effect in XNA 4.0: http://eng.utah.edu/~brendanw/question.jpg The purple area has 50% opacity. I have gotten pretty close with the following code: public static DepthStencilState AlwaysStencilState = new DepthStencilState() { StencilEnable = true, StencilFunction = CompareFunction.Always, StencilPass = StencilOperation.Replace, ReferenceStencil = 1, DepthBufferEnable = false, }; public static DepthStencilState EqualStencilState = new DepthStencilState() { StencilEnable = true, StencilFunction = CompareFunction.Equal, StencilPass = StencilOperation.Keep, ReferenceStencil = 1, DepthBufferEnable = false, }; ... if (_alphaEffect == null) { _alphaEffect = new AlphaTestEffect(_spriteBatch.GraphicsDevice); _alphaEffect.AlphaFunction = CompareFunction.LessEqual; _alphaEffect.ReferenceAlpha = 129; Matrix projection = Matrix.CreateOrthographicOffCenter(0, _spriteBatch.GraphicsDevice.PresentationParameters.BackBufferWidth, _spriteBatch.GraphicsDevice.PresentationParameters.BackBufferHeight, 0, 0, 1); _alphaEffect.Projection = world.SystemManager.GetSystem<RenderSystem>().Camera.View * projection; } _mask = new RenderTarget2D(_spriteBatch.GraphicsDevice, _spriteBatch.GraphicsDevice.PresentationParameters.BackBufferWidth, _spriteBatch.GraphicsDevice.PresentationParameters.BackBufferHeight, false, SurfaceFormat.Color, DepthFormat.Depth24Stencil8); _spriteBatch.GraphicsDevice.SetRenderTarget(_mask); _spriteBatch.GraphicsDevice.Clear(ClearOptions.Target | ClearOptions.Stencil, Color.Transparent, 0, 0); _spriteBatch.Begin(SpriteSortMode.Immediate, null, null, AlwaysStencilState, null, _alphaEffect); _spriteBatch.Draw(sprite.Texture, position, sprite.SourceRectangle,Color.White, 0f, sprite.Origin, 1f, SpriteEffects.None, 0); _spriteBatch.End(); _spriteBatch.Begin(SpriteSortMode.Immediate, null, null, EqualStencilState, null, null); _spriteBatch.Draw(_maskTex, new Vector2(x * _maskTex.Width, y * _maskTex.Height), null, Color.White, 0f, Vector2.Zero, 1f, SpriteEffects.None, 0); _spriteBatch.End(); _spriteBatch.GraphicsDevice.SetRenderTarget(null); _spriteBatch.GraphicsDevice.Clear(Color.Black); _spriteBatch.Begin(); _spriteBatch.Draw((Texture2D)_mask, Vector2.Zero, null, Color.White, 0f, Vector2.Zero, 1f, SpriteEffects.None, layer/max_layer); _spriteBatch.End(); My problem is, I can't get the AlphaTestEffect to behave. I can either mask over the semi-transparent purple junk and fill it in with the green design, or I can draw over the completely opaque grassy texture. How can I specify the exact opacity that needs to be replace with the green design?

    Read the article

  • Correct For Loop Design

    - by Yttrill
    What is the correct design for a for loop? Felix currently uses if len a > 0 do for var i in 0 upto len a - 1 do println a.[i]; done done which is inclusive of the upper bound. This is necessary to support the full range of values of a typical integer type. However the for loop shown does not support zero length arrays, hence the special test, nor will the subtraction of 1 work convincingly if the length of the array is equal to the number of integers. (I say convincingly because it may be that 0 - 1 = maxval: this is true in C for unsigned int, but are you sure it is true for unsigned char without thinking carefully about integral promotions?) The actual implementation of the for loop by my compiler does correctly handle 0 but this requires two tests to implement the loop: continue: if not (i <= bound) goto break body if i == bound goto break ++i goto continue break: Throw in the hand coded zero check in the array example and three tests are needed. If the loop were exclusive it would handle zero properly, avoiding the special test, but there'd be no way to express the upper bound of an array with maximum size. Note the C way of doing this: for(i=0; predicate(i); increment(i)) has the same problem. The predicate is tested after the increment, but the terminating increment is not universally valid! There is a general argument that a simple exclusive loop is enough: promote the index to a large type to prevent overflow, and assume no one will ever loop to the maximum value of this type.. but I'm not entirely convinced: if you promoted to C's size_t and looped from the second largest value to the largest you'd get an infinite loop!

    Read the article

  • HTG Projects: Create a Pop Art Sci-Fi Poster with an Inkjet Printer

    - by Eric Z Goodnight
    Looking to decorate your house with some cool artwork? Grab some of your favorite Sci-Fi pics and some surprisingly simple tools, and create a Pop Art style poster in minutes. Through a simple process called “posterization,” you can reduce any graphic into a cool limited graphic with a similar look that Andy Warhol would have used when he created his famous Marylin Monroe image in the sixties. Pick a theme, grab some images, and get ready to decorate your home with a surprisingly easy and surprisingly cool poster any inkjet printer can produce Latest Features How-To Geek ETC HTG Projects: How to Create Your Own Custom Papercraft Toy How to Combine Rescue Disks to Create the Ultimate Windows Repair Disk What is Camera Raw, and Why Would a Professional Prefer it to JPG? The How-To Geek Guide to Audio Editing: The Basics How To Boot 10 Different Live CDs From 1 USB Flash Drive The 20 Best How-To Geek Linux Articles of 2010 Arctic Theme for Windows 7 Gives Your Desktop an Icy Touch Install LibreOffice via PPA and Receive Auto-Updates in Ubuntu Creative Portraits Peek Inside the Guts of Modern Electronics Scenic Winter Lane Wallpaper to Create a Relaxing Mood Access Your Web Apps Directly Using the Context Menu in Chrome The Deep – Awesome Use of Metal Objects as Deep Sea Creatures [Video]

    Read the article

  • Red Dot Scope Makes Sighting In Long Lenses a Snap

    - by Jason Fitzpatrick
    If you’ve ever used a high power lens, you know how tricky it can be to sight a distant subject as the field of view through the lens is so tiny. This hack takes care of that problem by using a zero-magnification red dot rifle scope. Chris Malcolm enjoys photographing birds and other wildlife with high power lenses. The problem, when shooting with huge 500mm lens and other high power lenses, is that they’re practically telescopes and acquiring a fast moving target like a bird using a through-the-lens technique is very tricky. Malcolm’s solution hinges on mounting a zero-magnification red dot rifle scope in parallel with the lens. His mock up is a bit unpolished (although we can understand not wanting to run out and buy a brand new black scope just for the experiment) but works great to get him on target. Hit up the link below to read more about his build, how be created the rail mount for the scope, and why he opted to mount it to the barrel of the lens and not the hot shoe mount on the camera. 500mm Reflex Lens with Red Dot Sight [via DIY Photography] Make Your Own Windows 8 Start Button with Zero Memory Usage Reader Request: How To Repair Blurry Photos HTG Explains: What Can You Find in an Email Header?

    Read the article

  • Silverlight Cream for May 25, 2010 -- #869

    - by Dave Campbell
    In this Issue: Miroslav Miroslavov, Victor Gaudioso, Phil Middlemiss, Jonathan van de Veen, Lee, and Domagoj Pavlešic. From SilverlightCream.com: Book Folding effect using Pixel Shader On the new CompleteIT site, did you know the page-folding was done using PixelShaders? I hadn't put much thought into it, but that's pretty cool, and Miroslav Miroslavov has a blog post up discussing it, and the code behind it. New Silverlight Video Tutorial: How to create a Slider with a ToolTip that shows the Value of the Slider This is pretty cool... Victor Gaudioso's latest video tutorial shows how to put the slider position in the slider tooltip... code and video tutorial included. Backlighting a ListBox Put this in the cool category as well... Phil Middlemiss worked out a ListBox styling that makes the selected item be 'backlit' ... check out the screenshot on the post... and then grab the code :) Adventures while building a Silverlight Enterprise application part #33 Jonathan van de Veen is discussing changes to his project/team and how that has affected development. Read about what they did right and some of their struggles. RIA Services and Storedprocedures Lee's discussing Stored Procs and RIA Services ... he begins with one that just works, then moves on to demonstrate the kernel of the problem he's attacking and the solution of it. DoubleClick in Silverlight Domagoj Pavlešic got inspiration from one of Mike Snow's Tips of the Day and took off on the double-click idea... project source included. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

    Read the article

  • "Accumulate" buffer results in XNA4?

    - by Utkarsh Sinha
    I'm trying to simulate a "heightmap" buffer in XNA4.0 but the results don't look correct. Here's what I'm hoping to achieve: http://www.youtube.com/watch?feature=player_detailpage&v=-Q6ISVaM5Ww#t=517s (8:38). From what I understand, here are the steps to reach there: Pass height buffer + current entity's heightmap Generate a stencil and update the height buffer Render sprite+stencil For now, I'm just trying to get the height buffer thing to work. So here's the problem. Inside the draw loop, I do the following: Create a new render target & set it Draw the heightmap with a sprite batch(no shaders) graphicsDevice.SetRenderTarget(null) Draw the rendertarget with SpriteBatch I expected to see all entities' heightmaps. But only the last entity's heightmap is visible. Any hints on what I'm doing wrong? Here's the code inside the draw loop: RenderTarget2D tempDepthStencil = new RenderTarget2D(graphicsDevice, graphicsDevice.Viewport.Width, graphicsDevice.Viewport.Height, false, graphicsDevice.DisplayMode.Format, DepthFormat.None); graphicsDevice.SetRenderTarget(tempDepthStencil); // Gather depth information SpriteBatch depthStencilSpriteBatch = new SpriteBatch(graphicsDevice); depthStencilSpriteBatch.Begin(SpriteSortMode.Immediate, BlendState.AlphaBlend, SamplerState.LinearClamp, DepthStencilState.None, RasterizerState.CullCounterClockwise); depthStencilSpriteBatch.Draw(texHeightmap, pos, null, Color.White, 0, Vector2.Zero, 1, spriteEffects, 1); depthStencilSpriteBatch.End(); graphicsDevice.SetRenderTarget(null); SpriteBatch b1 = new SpriteBatch(graphicsDevice); b1.Begin(SpriteSortMode.Immediate, BlendState.AlphaBlend, null, null, null, null); b1.Draw((Texture2D)tempDepthStencil, Vector2.Zero, null, Color.White, 0, Vector2.Zero, 1, spriteEffects, 1); b1.End();

    Read the article

  • Tinkerforge Rotation/LCD & JavaFX Plans

    - by Geertjan
    The first time I integrated two Tinkerforge bricklets, the day before yesterday, was pretty cool: import com.tinkerforge.BrickMaster; import com.tinkerforge.BrickletLCD20x4; import com.tinkerforge.BrickletRotaryPoti; import com.tinkerforge.IPConnection; import java.util.Calendar; public class TFConnectionDemo { private static final String HOST = "localhost"; private static final int PORT = 4223; private static final String MASTERBRICKUID = "somethingabc"; private static final String LCDUID = "somethingabc"; private static final String ROTIUID = "somethingabc"; private static IPConnection ipc; private static BrickMaster master = new BrickMaster(MASTERBRICKUID); private static BrickletLCD20x4 lcd = new BrickletLCD20x4(LCDUID); private static BrickletRotaryPoti poti = new BrickletRotaryPoti(ROTIUID); public static void main(String[] args) { try { ipc = new IPConnection(HOST, PORT); ipc.addDevice(master); ipc.addDevice(lcd); ipc.addDevice(poti); poti.setPositionCallbackPeriod(50); poti.addListener(new BrickletRotaryPoti.PositionListener() { @Override public void position(short position) { lcd.clearDisplay(); Calendar cal = Calendar.getInstance(); lcd.writeLine((short) 0, (short) 0, cal.getTime().toString()); lcd.writeLine((short) 1, (short) 0, "Rotation: " + position); } }); } catch (Exception e) { } } } The result is that the display text in the LCD bricklet changes while I turn the rotation bricklet: Now imagine that you have some JavaFX charts and, while you turn the rotation bricklet (i.e., the dial thing that I'm turning above), the values of the charts change. That would be pretty cool because you'd be able to animate the JavaFX charts by rotating an object externally, i.e., without even touching the keyboard. That would be pretty cool to see and shouldn't be hard to implement.

    Read the article

  • how to choose a web framework and javascript library?

    - by Trylks
    I've been procrastinating learning some framework for web apps w/ some library for AJAX, something like django with prototype, or turbogears with mootools, or zeta components with dojo, grok, jquery, symfony... The point is to spend some of my spare time, have "fun" and create cool stuff that hopefully is some useful. I think maybe I wouldn't like something like GWT or pyjamas because I wouldn't like to "get married" with some technology, I want to keep my freedom to add another javascript library, and so on. I didn't decide even the language yet, but I think I'd prefer python. PHP could be fine if there is some framework that is nice enough. Besides that, I don't even know where to start. I don't feel like learning a framework to then realize there is something that I cannot comfortably do, switch to another framework then find that a third framework has something really cool, etc. And the same goes for javascript libraries. So, some guidance would be really appreciated. I don't really know why are so many options available and what do they aim for, I guess some of them focus on some aspects and some on others, but I just want to make cool and nice apps that I can easily maintain, without spending too much time on coding or learning and avoiding the "trapped in the framework" feeling, when doing something is awfully complicated (or even impossible) with compared with the rest of things or doing that same thing on a different framework. I guess in the end I'll go for django and jquery since they are the most widely used options, afaik, but if I was going for the most widely used options I guess I should choose Java or PHP (I don't really like Java for my spare time, but php is not so bad), so I preferred to ask first. I think the question has to consider both, framework and library, since sometimes they are coupled. I think this is the place to ask this kind of things, sorry if not, and thank you.

    Read the article

< Previous Page | 18 19 20 21 22 23 24 25 26 27 28 29  | Next Page >