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  • How to place additional access-restrictions on a subdirectory in Apache?

    - by Mikhail T.
    We have a list of "internal" IP-addresses and only allow access to the server (Location /) from that list: <Location /> Require ip x.x.x.x Require ip y.y.y.y </Location> I need to further restrict access to a sub-directory (Location /foo) to authenticated users (Require valid-user). Whatever I do, I never get prompted for login to access /foo -- Apache simply grants me access, because my IP-address is on the list (for Location /). I cycled through all three different values of AuthMerging (off, and, or) to no avail... Must be something really stupid :-/ Using httpd-2.4.6. Thank you!

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  • Apache Subversion and Sudo - Why can't I resolve this hostname?

    - by Hollowsteps
    Okay, I made a mistake and I'll be the first to admit I'm new at this setup. I built a bare bones kit, installed Ubuntu on it, and attempted to set up a source control server for a project some friend and I were going to work on. Unfortunately, I screwed up. I followed a dodgy tutorial from 2005 and when it didn't work, started mixing and matching trying to get to the source of my problem. So now I sit before you, a broken and miserable man. Desperate to escape this annoying echo of 'Unable to resolve host computer.repositoryname.com', I uninstalled apache and subversion. That did not fix it. Next I tried to edit my /etc/hosts, going so far as to remove the reference to '127.0.1.1 computername'. Still I'm plagued. I know I messed up, is there any way to track down this wayward bug?

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  • windows VPS running apache and mysql, php scripts running slow.. but cpu usage is 1-3%..

    - by Roeland
    So every night I run some cron jobs. It requires probably about 20 min to process all the records. I gather the script does something like 10,000 sql queries. I figure this task was just that intense and needs time to complete, but I looked at CPU and memory usage, and it is super low. Cpu usage is between 1-3% and once in a while will bounce to 50ish for 2-3 seconds. This VPS is running windows 2003 server with Apache and MySQL. Does this sound right?

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  • How to allow Mac OS X's native Apache/PHP installation to access WebServer directories?

    - by Martin Bean
    I have a problem bugging me with Mac OS X's native Apache/PHP installation. With my PHP scripts, I have to alter the file permissions on each folder I want to access. For example, in an upload script I would have to set the destination directory to 'read & write' for the group 'everyone'. However, I believe this is not the best practice and would like all of my directories to be readily writable to PHP. My scripts are stored in /Library/WebServer/Documents/, which is Mac OS X's default directory to serve web pages locally.

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  • New to Apache: what exacty should my conf file contain for a basic forward proxy?

    - by HankJDoomstorm
    Hi, I was hoping to get some help setting up Apache as a forward proxy, primarily just to know how it's done and for learning. I've found countless examples that look a lot like this: <IfModule mod_proxy> ProxyRequests On ProxyVia On <Proxy *> Allow from all </Proxy> But I'm not sure what to do with that information. What happens in the rest of the conf file? Do I just append it to the bottom and activate all the proxy modules? And if so, why isn't working when I try it with Firefox? Thanks

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  • What does Apache need to support both mysqli and PDO?

    - by Nathan Long
    I'm considering changing some PHP code to use PDO for database access instead of mysqli (because the PDO syntax makes more sense to me and is database-agnostic). To do that, I'd need both methods to work while I'm making the changeover. My problem is this: so far, either one or the other method will crash Apache. Right now I'm using XAMPP in Windows XP, and PHP Version 5.2.8. Mysqli works fine, and so does this: $dbc = new PDO("mysql:host=$hostname;dbname=$dbname", $username, $password); echo 'Connected to database'; $sql = "SELECT * FROM `employee`"; But this line makes Apache crash: $dbc->query($sql); I don't want to redo my entire Apache or XAMPP installation, but I'd like for PDO to work. So I tried updating libmysql.dll from here, as oddvibes recommended here. That made my simple PDO query work, but then mysqli queries crashed Apache. (I also tried the suggestion after that one, to update php_pdo_mysql.dll and php_pdo.dll, to no effect.) Test Case I created this test script to compare PDO vs mysqli. With the old copy of libmysql.dll, it crashes if $use_pdo is true and doesn't if it's false. With the new copy of libmysql.dll, it's the opposite. if ($use_pdo){ $dbc = new PDO("mysql:host=$hostname;dbname=$dbname", $username, $password); echo 'Connected to database<br />'; $sql = "SELECT * FROM `employee`"; $dbc->query($sql); foreach ($dbc->query($sql) as $row){ echo $row['firstname'] . ' ' . $row['lastname'] . "<br>\n"; } } else { $dbc = @mysqli_connect($hostname, $username, $password, $dbname) OR die('Could not connect to MySQL: ' . mysqli_connect_error()); $sql = "SELECT * FROM `employee`"; $result = @mysqli_query($dbc, $sql) or die(mysqli_error($dbc)); while ($row = mysqli_fetch_array($result,MYSQLI_ASSOC)) { echo $row['firstname'] . ' ' . $row['lastname'] . "<br>\n"; } } What does Apache need in order to support both methods of database query?

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  • Conditional https redirect to http depending on URL? (Apache)

    - by Joel Marcey
    Right now I redirect 100% of the time if someone does https://mysite.com <VirtualHost *:443> ServerAdmin [email protected] ServerName mysite.com ServerAlias www.mysite.com RewriteEngine on RewriteRule (.*) http://%{HTTP_HOST} [L,R=permanent] <VirtualHost> However, now I want to conditionally redirect. If a user goes to https://mysite.com/abc/, then I want to use https; otherwise redirect. How do I do this? I tried reading the docs, but just couldn't find what I needed. I am using Apache on Ubuntu Linux.

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  • Javascript for a prompt which accepts simple math as a value and then returns the answer

    - by user1139403
    I have written a snippet of code in javascript, for a prompt to appear when clicked. I want to be able to enter a simple math problem (i.e. 230/2) and have it output the answer, rather than the math problem I just entered. Your help will be much appreciated. <!DOCTYPE html> <html> <body> <button onclick="myFunction()">Click me</button> <p id="demo"></p> <script type="text/javascript"> function myFunction() { var x; var mathProblem=prompt("Enter your math problem",""); if (name!=null) { x = mathProblem; document.getElementById("demo").innerHTML = x; } } </script> </body> </html>

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  • Is it possible to host a website with Apache HTTP through a ZyXEL EQ-660R modem and a Netgear WGT624v3 wireless router?

    - by Vortico
    Essentially, I have a spare desktop computer I'd like to turn into a web server, but my modem and wireless router are very difficult to work with. I installed Apache HTTP and successfully hosted a test page which can be accessed anywhere on the LAN. However, I'm having trouble setting up the server to be accessed from my external IP address. I was supplied with a ZyXEL EQ-660R DSL modem by my ISP (CenturyLink) and bought a Netgear WGT624v3 wireless router in which to connect my laptop and spare desktop. ZyXEL's website is no help, and I don't think much of the problem is with the Netgear router. I've played with many settings and have tried to forward port 80 from the modem, but I've had no luck. Could someone direct me toward a solution or recommendations for more promising hardware? Or should I admit defeat and explore other hobbies? :)

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  • Permissions problem running Apache ActiveMQ

    - by Edd
    I'm wanting to use Apache ActiveMQ on Ubuntu 12.04 LTS, but am running into what looks like a permissions problem when I try to run it as follows: edd:~$ sudo activemq --version INFO: Loading '/usr/share/activemq/activemq-options' INFO: Using java '/usr/lib/jvm/java-6-openjdk//bin/java' INFO: changing to user 'activemq' to invoke java Java Runtime: Sun Microsystems Inc. 1.6.0_24 /usr/lib/jvm/java-6-openjdk-amd64/jre Heap sizes: current=502464k free=499842k max=502464k JVM args: -Xms512M -Xmx512M -Dorg.apache.activemq.UseDedicatedTaskRunner=true -Dactivemq.classpath=/var/lib/activemq//conf;; -Dactivemq.home=/usr/share/activemq -Dactivemq.base=/var/lib/activemq/ ACTIVEMQ_HOME: /usr/share/activemq ACTIVEMQ_BASE: /var/lib/activemq ActiveMQ 5.5.0 For help or more information please see: http://activemq.apache.org edd:~$ sudo activemq start INFO: Loading '/usr/share/activemq/activemq-options' INFO: Using java '/usr/lib/jvm/java-6-openjdk//bin/java' INFO: Starting - inspect logfiles specified in logging.properties and log4j.properties to get details INFO: changing to user 'activemq' to invoke java -su: line 2: /var/run/activemq.pid: Permission denied INFO: pidfile created : '/var/run/activemq.pid' (pid '7811') edd:~$ sudo activemq status INFO: Loading '/usr/share/activemq/activemq-options' INFO: Using java '/usr/lib/jvm/java-6-openjdk//bin/java' ActiveMQ not running edd:~$ ps ax | grep 'activemq' 8040 pts/0 S+ 0:00 grep --color=auto activemq I installed ActiveMQ using sudo apt-get install activemq. Apologies if there's any additional information missing - I'm fairly new to Linux as you may well have guessed!

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  • Can't install Apache 2.2.22 on Ubuntu 13.10

    - by B18C1
    My work environment requires Apache 2.2.22 instead of the latest version of 2.4. My machine is currently running Ubuntu 13.10. When I use Synaptic or apt-get it will not allow me to choose an older version of Apache than 2.4. So my question is, how can I force an install of Apache 2.2.22 on Ubuntu 13.10 using Synaptic or apt-get. When I do try to specify the version I get the following: sudo apt-get install apache2=2.2.22-1ubuntu1 [sudo] password for b18c1: Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: apache2 : Depends: apache2-mpm-worker (= 2.2.22-1ubuntu1) but it is not going to installed or apache2-mpm-prefork (= 2.2.22-1ubuntu1) but it is not going to be installed or apache2-mpm-event (= 2.2.22-1ubuntu1) but it is not going to be installed or apache2-mpm-itk (= 2.2.22-1ubuntu1) but it is not going to be installed Depends: apache2.2-common (= 2.2.22-1ubuntu1) but it is not going to be installed E: Unable to correct problems, you have held broken packages.

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  • Understanding normal maps on terrain

    - by JohnB
    I'm having trouble understanding some of the math behind normal map textures even though I've got it to work using borrowed code, I want to understand it. I have a terrain based on a heightmap. I'm generating a mesh of triangles at load time and rendering that mesh. Now for each vertex I need to calculate a normal, a tangent, and a bitangent. My understanding is as follows, have I got this right? normal is a unit vector facing outwards from the surface of the triangle. For a vertex I take the average of the normals of the triangles using that vertex. tangent is a unit vector in the direction of the 'u' coordinates of the texture map. As my texture u,v coordinates follow the x and y coordinates of the terrain, then my understanding is that this vector is simply the vector along the surface in the x direction. So should be able to calculate this as simply the difference between vertices in the x direction to get a vector, (and normalize it). bitangent is a unit vector in the direction of the 'v' coordinates of the texture map. As my texture u,v coordinates follow the x and y coordinates of the terrain, then my understanding is that this vector is simply the vector along the surface in the y direction. So should be able to calculate this as simply the difference between vertices in the y direction to get a vector, (and normalize it). However the code I have borrowed seems much more complicated than this and takes into account the actual values of u, and v at each vertex which I don't understand the need for as they increase in exactly the same direction as x, and y. I implemented what I thought from above, and it simply doesn't work, the normals are clearly not working for lighting. Have I misunderstood something? Or can someone explain to me the physical meaning of the tangent and bitangent vectors when applied to a mesh generated from a hightmap like this, when u and v texture coordinates map along the x and y directions. Thanks for any help understanding this.

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  • 3D Vector "End Point" Calculation for procedural Vector Graphics

    - by FrostFlame64
    Alright, So I need some help with some Vector Math. I've developing some game Engines that have Procedural Fractal Generation for Some Graphics, such as using Lindenmayer Systems for generating Trees and Plants. L-Systems, are drawn by using Turtle Graphics, which is a form of Vector graphics. I first created a system to draw in 2D Graphics, which works perfectly fine. But now I want to make a 3D equivalent, and I’ve run into an issue. For my 2D Version, I created a Method for quickly determining the “End Point” of a Vector-like movement. Given a starting point (X, Y), a direction (between 0 and 360 degrees), and a distance, the end point is calculated by these formulas: newX = startX + distance * Sin((PI * direction) / 180) newY = startY + distance * Cos((PI * direction) / 180) Now I need something Similarly Equivalent for performing this Calculation in 3D, But I haven’t been able to Google anything that could show me how to do this. I'm flexible enough to get whatever required information is needed for this method calculation, in any reasonable form (Vector3, Quaternion, ect). To summarize: Given a starting point/vector position in 3D space (X, Y, Z), a Direction in 3D space (Vector3, Quaternion, ect), and a Distance, I need to find the “End Point” in 3D Space. Thank you for your time and help.

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  • XSF-FO intellisense and national languages with Apache FOP

    - by Lukasz Kurylo
    Some time ago I showed how to get an intellisense and how to configure the FO.NET to acquire national characters inside the generated pdf files. Due to the limitations that I mensioned in my previous post, I started playing with the Apache FOP. In this post I want to show, how to acquire the same result as I showed in the two posts related to FO.NET.   Intellisense   To get the intellisense from the XSL-FO templates set the xsi:schemaLocation the same way I showed it in this post. The only diffrence to FO.NET is that, during generating the document by the code I showed last time we will get an exception:   org.apache.fop.fo.ValidationException: Invalid property encountered on "fo:root": xsi:schemaLocation (See position 6:11)   Fortunatelly there is a very easy way to resolve this without removing the entire attribute along with the intellisense. Add to the FopFactory the ignoreNamespace by:   FopFactory fopFactory = FopFactory.newInstance(); fopFactory.ignoreNamespace(http://www.w3.org/2001/XMLSchema-instance);   Notice that, the url specified in this method this is a namespace for the xmlns:xsi namespace, not xsi.schemaLocation.   Fonts / national characters   This point is a little dfferent to acquire, but not more complicated that it was with FO.NET. To set the fonts in Apache FOP 1.0, we need a configuration file. A sample one can be get from the directory where we unpacked the fop binaries, from conf subdirectory. There is a file called fop.xconf. We must copy this file to our solution. In the simplest way, in the <fonts> tag we can add  <auto-detect/>. Thanks to this, FOP will index all fonts available on the installed operating system. There probably should be no problem, if we have a http handler or a WCF Service on the server that serves the generated pdf documents. In this situation we can use all available fonts on this server.   To use this config file, we must set a path to it:   FopFactory fopFactory = FopFactory.newInstance(); fopFactory.setUserConfig(new File("fop.xconf"));

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  • Calculating 3d rotation around random axis

    - by mitim
    This is actually a solved problem, but I want to understand why my original method didn't work (hoping someone with more knowledge can explain). (Keep in mind, I've not very experienced in 3d programming, having only played with the very basic for a little bit...nor do I have a lot of mathematical experience in this area). I wanted to animate a point rotating around another point at a random axis, say a 45 degrees along the y axis (think of an electron around a nucleus). I know how to rotate using the transform matrix along the X, Y and Z axis, but not an arbitrary (45 degree) axis. Eventually after some research I found a suggestion: Rotate the point by -45 degrees around the Z so that it is aligned. Then rotate by some increment along the Y axis, then rotate it back +45 degrees for every frame tick. While this certainly worked, I felt that it seemed to be more work then needed (too many method calls, math, etc) and would probably be pretty slow at runtime with many points to deal with. I thought maybe it was possible to combine all the rotation matrixes involve into 1 rotation matrix and use that as a single operation. Something like: [ cos(-45) -sin(-45) 0] [ sin(-45) cos(-45) 0] rotate by -45 along Z [ 0 0 1] multiply by [ cos(2) 0 -sin(2)] [ 0 1 0 ] rotate by 2 degrees (my increment) along Y [ sin(2) 0 cos(2)] then multiply that result by (in that order) [ cos(45) -sin(45) 0] [ sin(45) cos(45) 0] rotate by 45 along Z [ 0 0 1] I get 1 mess of a matrix of numbers (since I was working with unknowns and 2 angles), but I felt like it should work. It did not and I found a solution on wiki using a different matirx, but that is something else. I'm not sure if maybe I made an error in multiplying, but my question is: this is actually a viable way to solve the problem, to take all the separate transformations, combine them via multiplying, then use that or not?

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  • Japanese Multiplication simulation - is a program actually capable of improving calculation speed?

    - by jt0dd
    On SuperUser, I asked a (possibly silly) question about processors using mathematical shortcuts and would like to have a look at the possibility at the software application of that concept. I'd like to write a simulation of Japanese Multiplication to get benchmarks on large calculations utilizing the shortcut vs traditional CPU multiplication. I'm curious as to whether it makes sense to try this. My Question: I'd like to know whether or not a software math shortcut, as described above is actually a shortcut at all. This is a question of programming concept. By utilizing the simulation of Japanese Multiplication, is a program actually capable of improving calculation speed? Or am I doomed from the start? The answer to this question isn't required to determine whether or not the experiment will succeed, but rather whether or not it's logically possible for such a thing to occur in any program, using this concept as an example. My theory is that since addition is computed faster than multiplication, a simulation of Japanese multiplication may actually allow a program to multiply (large) numbers faster than the CPU arithmetic unit can. I think this would be a very interesting finding, if it proves to be true. If, in the multiplication of numbers of any immense size, the shortcut were to calculate the result via less instructions (or faster) than traditional ALU multiplication, I would consider the experiment a success.

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  • Vector vs Scalar velocity?

    - by Serguei Fedorov
    I am revamping an engine I have been working on and off on for the last few weeks to use a directional vector to dictate direction; this way I can dictate the displacement based on a direction. However, the issue I am trying to overcome is the following problem; the speed towards X and speed towards Y are unrelated to one another. If gravity pulls the object down by an increasing velocity my velocity towards the X should not change. This is very easy to implement if my speed is broken into a Vector datatype, Vector.X dictates one direction Vector.Y dictates the other (assuming we are not concerned about the Z axis). However, this defeats the purpose of the directional vector because: SpeedX = 10 SpeedY = 15 [1, 1] normalized = ~[0.7, 0.7] [0.7, 0.7] * [10, 15] = [7, 10.5] As you can see my direction is now "scaled" to my speed which is no longer the direction that I want to be moving in. I am very new to vector math and this is a learning project for me. I looked around a little bit on the internet but I still want to figure out things on my own (not just look at an example and copy off it). Is there way around this? Using a directional vector is extremely useful but I am a little bit stumped at this problem. I am sorry if my mathematical understanding maybe completely wrong.

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  • JavaScript 3D space ship rotation

    - by user36202
    I am working with a fairly low-level JavaScript 3D API (not Three.js) which uses euler angles for rotation. In most cases, euler angles work quite well for doing things like aligning buildings, operating a hovercraft, or looking around in the first-person. However, in space there is no up or down. I want to control the ship's roll, pitch, and yaw. To do that, some people would use a local coordinate system or a permenant matrix or quaternion or whatever to represent the ship's angle. However, since I am not most people and am using a library that deals exclusively in euler angles, I will be using relative angles to represent how to rotate the ship in space and getting the resulting non-relative euler angles. For you math nerds, that means I need to convert 3 euler angles (with Y being the vertical axis, X representing the pitch, and Z representing a roll which is unaffected by the other angles, left-handed system) into a 3x3 orientation matrix, do something fancy with the matrix, and convert it back into the 3 euler angles. Euler to matrix to euler. Somebody has posted something similar to this on SO (http://stackoverflow.com/questions/1217775/rotating-a-spaceship-model-for-a-space-simulator-game) but he ended up just working with a matrix. This will not do for me. Also, I am using JavaScript, not C++. What I want essentially are the functions do_roll, do_pitch, and do_yaw which only take in and put out euler angles. Many thanks.

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  • Line Intersection from parametric equation

    - by Sidar
    I'm sure this question has been asked before. However, I'm trying to connect the dots by translating an equation on paper into an actual function. I thought It would be interesting to ask here instead on the Math sites (since it's going to be used for games anyway ). Let's say we have our vector equation : x = s + Lr; where x is the resulting vector, s our starting point/vector. L our parameter and r our direction vector. The ( not sure it's called like this, please correct me ) normal equation is : x.n = c; If we substitute our vector equation we get: (s+Lr).n = c. We now need to isolate L which results in L = (c - s.n) / (r.n); L needs to be 0 < L < 1. Meaning it needs to be between 0 and 1. My question: I want to know what L is so if I were to substitute L for both vector equation (or two lines) they should give me the same intersection coordinates. That is if they intersect. But I can't wrap my head around on how to use this for two lines and find the parameter that fits the intersection point. Could someone with a simple example show how I could translate this to a function/method?

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  • Setting up multiple cores for apache solr for Ubuntu 12.04 and Drupal 7

    - by chrisjlee
    I'm setting up solr locally for my development purposes and integration with Drupal 7. I'm not very familiar with tomcat. My background has primarily been LAMP setups. So I went and installed the package provided by ubuntu for apache solr following this guide. sudo apt-get install tomcat6 tomcat6-admin tomcat6-common tomcat6-user tomcat6-docs tomcat6-examples sudo apt-get install solr-tomcat I've got that working. The apt-get package manager does a great job and allows me to setup solr but with one core. What steps need to be taken to enable multi core setup for apache solr? And below is my solr.xml file: sudo nano /var/lib/tomcat6/conf/Catalina/localhost/solr.xml <!-- Context configuration file for the Solr Web App --> <Context path="/solr" docBase="/usr/share/solr" debug="0" privileged="true" allowLinking="true" crossContext="true"> <!-- make symlinks work in Tomcat --> <Resources className="org.apache.naming.resources.FileDirContext" allowLinking="true" /> <Environment name="solr/home" type="java.lang.String" value="/usr/share/solr" override="true" /> </Context>

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  • Calculating the correct particle angle in an outwards explosion

    - by Sun
    I'm creating a simple particle explosion but am stuck in finding the correct angle to rotate my particle. The effect I'm going for is similar to this: Where each particle is going outwards from the point of origin and at the correct angle. This is what I currently have: As you can see, each particle is facing the same angle, but I'm having a little difficulty figuring out the correct angle. I have the vector for the point of emission and the new vector for each particle, how can I use this to calculate the angle? Some code for reference: private Particle CreateParticle() { ... Vector2 velocity = new Vector2(2.0f * (float)(random.NextDouble() * 2 - 1), 2.0f * (float)(random.NextDouble() * 2 - 1)); direction = velocity - ParticleLocation; float angle = (float)Math.Atan2(direction.Y, direction.X); ... return new Particle(texture, position, velocity, angle, angularVelocity, color, size, ttl, EmitterLocation); } I am then using the angle created as so in my particles Draw method: spriteBatch.Draw(Texture, Position, null, Color, Angle, origin, Size, SpriteEffects.None, 0f);

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  • Recreating Doodle Jump in Canvas - Platforms spawning out of reach

    - by kushsolitary
    I have started to recreate Doodle Jump in HTML using Canvas. Here's my current progress. As you can see, if you play it for a few seconds, some platforms will be out of the player's reach. I don't know why is this happening. Here's the code which is responsible for the re-spawning of platforms. //Movement of player affected by gravity if(player.y > (height / 2) - (player.height / 2)) { player.y += player.vy; player.vy += gravity; } else { for(var i = 0; i < platforms.length; i++) { var p = platforms[i]; if(player.vy < 0) { p.y -= player.vy; player.vy += 0.08; } if(p.y > height) { position = 0; var h = p.y; platforms[i] = new Platform(); } if(player.vy >= 0) { player.y += player.vy; player.vy += gravity; } } } Also, here's the platform class. //Platform class function Platform(y) { this.image = new Image(); this.image.src = platformImg; this.width = 105; this.height = 25; this.x = Math.random() * (width - this.width); this.y = y || position; position += height / platformCount; //Function to draw it this.draw = function() { try { ctx.drawImage(this.image, this.x, this.y, this.width, this.height); } catch(e) {} }; } You can also see the whole code on the link I provided. Also, when a platform goes out of the view port, the jump animation becomes quirky. I am still trying to find out what's causing this but can't find any solution.

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  • Spherical to Cartesian Coordinates

    - by user1258455
    Well I'm reading the Frank's Luna DirectX10 book and, while I'm trying to understand the first demo, I found something that's not very clear at least for me. In the updateScene method, when I press A, S, W or D, the angles mTheta and mPhi change, but after that, there are three lines of code that I don't understand exactly what they do: // Convert Spherical to Cartesian coordinates: mPhi measured from +y // and mTheta measured counterclockwise from -z. float x = 5.0f*sinf(mPhi)*sinf(mTheta); float z = -5.0f*sinf(mPhi)*cosf(mTheta); float y = 5.0f*cosf(mPhi); I mean, this explains that they do, it says that it converts the spherical coordinates to cartesian coordinates, but, mathematically, why? why the x value is calculated by the product of the sins of both angles? And the z by the product of the sine and cosine? and why the y just uses the cosine? After that, those values (x, y and z) are used to build the view matrix. The book doesn't explain (mathematically) why those values are calculated like that (and I didn't find anything to help me to understand it at the first Part of the book: "Mathematical prerequisites"), so it would be good if someone could explain me what exactly happen in those code lines or just give me a link that helps me to understand the math part. Thanks in advance!

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  • Restrict movement within a radius

    - by Phil
    I asked a similar question recently but now I think I know more about what I really want to know. I can answer my own question if I get to understand this bit. I have a situation where a sprite's center point needs to be constrained within a certain boundary in 2d space. The boundary is circular so the sprite is constrained within a radius. This radius is defined as a distance from the center of a certain point. I know the position of the center point and I can track the center position of the sprite. This is the code to detect the distance: float distance = Vector2.Distance(centerPosition, spritePosition)); if (distance > allowedDistance) { } The positions can be wherever on the grid, they are not described as in between -1 or 1. So basically the detecting code works, it only prints when the sprite is outside of it's boundary I just don't know what to do when it oversteps. Please explain any math used as I really want to understand what you're thinking to be able to elaborate on it myself.

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  • Cube rotation DX10

    - by German
    Well I'm reading the Frank's Luna DirectX10 book and, while I'm trying to understand the first demo, I found something that's not very clear at least for me. In the updateScene method, when I press A, S, W or D, the angles mTheta and mPhi change, but after that, there are three lines of code that I don't understand exactly what they do: // Convert Spherical to Cartesian coordinates: mPhi measured from +y // and mTheta measured counterclockwise from -z. float x = 5.0f*sinf(mPhi)*sinf(mTheta); float z = -5.0f*sinf(mPhi)*cosf(mTheta); float y = 5.0f*cosf(mPhi); I mean, this explains that they do, it says that it converts the spherical coordinates to cartesian coordinates, but, mathematically, why? why the x value is calculated by the product of the sins of both angles? And the z by the product of the sine and cosine? and why the y just uses the cosine? After that, those values (x, y and z) are used to build the view matrix. The book doesn't explain (mathematically) why those values are calculated like that (and I didn't find anything to help me to understand it at the first Part of the book: "Mathematical prerequisites"), so it would be good if someone could explain me what exactly happen in those code lines or just give me a link that helps me to understand the math part. Thanks in advance!

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