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  • How can I call the iPhone to draw using other method?

    - by Tattat
    I have a view with a class called "drawingViewController", and I have the drawRect method: - (void)drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetLineWidth(context, 2.0); CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor); CGContextMoveToPoint(context, 0.0f, 0.0f); CGContextAddLineToPoint(context, 100.0f, 100.0f); CGContextStrokePath(context); } But I wanna to define some other drawing method, but it did't work, how can I do so apart from calling drawRect method? thz in advance.

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  • Ray Generation Inconsistency

    - by Myx
    I have written code that generates a ray from the "eye" of the camera to the viewing plane some distance away from the camera's eye: R3Ray ConstructRayThroughPixel(...) { R3Point p; double increments_x = (lr.X() - ul.X())/(double)width; double increments_y = (ul.Y() - lr.Y())/(double)height; p.SetX( ul.X() + ((double)i_pos+0.5)*increments_x ); p.SetY( lr.Y() + ((double)j_pos+0.5)*increments_y ); p.SetZ( lr.Z() ); R3Vector v = p-camera_pos; R3Ray new_ray(camera_pos,v); return new_ray; } ul is the upper left corner of the viewing plane and lr is the lower left corner of the viewing plane. They are defined as follows: R3Point org = scene->camera.eye + scene->camera.towards * radius; R3Vector dx = scene->camera.right * radius * tan(scene->camera.xfov); R3Vector dy = scene->camera.up * radius * tan(scene->camera.yfov); R3Point lr = org + dx - dy; R3Point ul = org - dx + dy; Here, org is the center of the viewing plane with radius being the distance between the viewing plane and the camera eye, dx and dy are the displacements in the x and y directions from the center of the viewing plane. The ConstructRayThroughPixel(...) function works perfectly for a camera whose eye is at (0,0,0). However, when the camera is at some different position, not all needed rays are produced for the image. Any suggestions what could be going wrong? Maybe something wrong with my equations? Thanks for the help.

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  • How do I find hash value of a 3D vector ?

    - by brainydexter
    I am trying to perform broad-phase collision detection with a fixed-grid size approach. Thus, for each entity's position: (x,y,z) (each of type float), I need to find which cell does the entity lie in. I then intend to store all the cells in a hash-table and then iterate through to report (if any) collisions. So, here is what I am doing: Grid-cell's position: (int type) (Gx, Gy, Gz) = (x / M, y / M, z / M) where M is the size of the grid. Once, I have a cell, I'd like to add it to a hash-table with its key being a unique hash based on (Gx, Gy, Gz) and the value being the cell itself. Now, I cannot think of a good hash function and I need some help with that. Can someone please suggest me a good hash function? Thanks

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  • Understanding colors

    - by Ankur Gupta
    Hello everyone, Kindly point towards theory/material to read for understanding colors and what makes a good color combinations. Mind it that I am not interested in say "Color combinations for web application" etc. More of the lines of say "Colors and humans". Material free to read is what i am looking for. Thanks

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  • Coordinates in distorted grid

    - by Carsten
    I have a grid in a 2D system like the one in the before image where all points A,B,C,D,A',B',C',D' are given (meaning I know the respective x- and y-coordinates). I need to calculate the x- and y-coordinates of A(new), B(new), C(new) and D(new) when the grid is distorted (so that A' is moved to A'(new), B' is moved to B'(new), C' is moved to C'(new) and D' is moved to D'(new)). The distortion happens in a way in which the lines of the grid are each divided into sub-lines of equal length (meaning for example that AB is divided into 5 parts of the equal length |AB|/5 and A(new)B(new) is divided into 5 parts of the equal length |A(new)B(new)|/5). The distortion is done with the DistortImage class of the Sandy 3D Flash engine. (My practical task is to distort an image using this class where the handles are not positioned at the corners of the image like in this demo but somewhere within it).

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  • Quartz2d vector images vs OpenGL vector description?

    - by tbarbe
    How big of a difference is the description language of Quartz2d to OpenGL ES? It seems they are similar in description power... except that Quartz is mostly 2d and that OpenGL is out of the box 3d ( but can be made 2d focused ). Are the mappings from 2dQuartz to 2d OpenGL ES that different? Im sure there must be differences in some specific features that might be handled differently on one vs another... but to do a translator? Anyone have experience with both OpenGL and Quartz2d have some insights?

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  • java/swing: Shape questions: serializing and combining

    - by Jason S
    I have two questions about java.awt.Shape. Suppose I have two Shapes, shape1 and shape2. How can I serialize them in some way so I can save the information to a file and later recreate it on another computer? (Shape is not Serializable but it does have the getPathIterator() method which seems like you could get the information out but it would be kind of a drag + I'm not sure how to reconstruct a Shape object afterwards.) How can I combine them into a new Shape so that they form a joint boundary? (e.g. if shape1 is a large square and shape2 is a small circle inside the square, I want the combined shape to be a large square with a small circular hole)

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  • solving origin of a vectors

    - by Mike
    I have two endpoints (xa,ya) and (xb,yb) of two vectors, respectively a and b, originating from a same point (xo, yo). Also, I know that |a|=|b|+s, where s is a constant. I tried to compute the origin (xo, yo) but seem to fail at some point. How to solve this?

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  • What is the equivalent to Java's canvas object in C#?

    - by Winston
    I'm working on creating a basic application that will let a user draw (using a series of points) and I plan to do something with these points. If this were Java, I think I would probably use a canvas object and some Java2D calls to draw what I want. All the tutorials I've read on C#/Drawing involve writing your own paint method and adding it to the paint event for the form. However, I'm interested in having some traditional Form controls as well and I don't want to be drawing over them. So, is there a "Canvas" object where I can constrain what I'm drawing on? Also, is WinForms a poor choice given this use case? Would WPF have more features that would help enable me to do what I want? Or Silverlight?

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  • Java2d: Set gradient for a lines

    - by Algorist
    Hi, I am having multiple points in a plane and some hundreds of lines pass through those points. Some points can have more lines passing through them than other points. I want to show some kind of more gradient or brightness associated with lines crowded together. Is this possible to do in java2d. Please refer to this : http://ft.ornl.gov/doku/_media/ft/projects/paraxis.jpg Thank you.

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  • What are some good algorithms for drawing lines between graph nodes?

    - by ApplePieIsGood
    What I'm specifically grappling with is not just the layout of a graph, but when a user selects a graph node and starts to drag it around the screen area, the line has to constantly be redrawn to reflect what it would look like if the user were to release the node. I suppose this is part of the layout algorithm? Also some applications get a bit fancy and don't simply draw the line in a nice curvy way, but also bend the line around the square shaped node in almost right angles. See attached image and keep in mind that as a node is dragged, the line is drawn as marching ants, and re-arranged nicely, while retaining its curved style.

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  • Custom UILabel does not show text.

    - by Oscar
    Hi! I've made an custom UILabel class in which i draw a red line at the bottom of the frame. The red line is showing but i cant get the text to show. #import <UIKit/UIKit.h> @interface LetterLabel : UILabel { } @end #import "LetterLabel.h" @implementation LetterLabel - (id)initWithFrame:(CGRect)frame { if (self = [super initWithFrame:frame]) { // Initialization code } return self; } - (void)drawRect:(CGRect)rect { CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 2.0); CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0); CGContextBeginPath(UIGraphicsGetCurrentContext()); CGContextMoveToPoint(UIGraphicsGetCurrentContext(), 0.0, self.frame.size.height); CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), self.frame.size.width, self.frame.size.height); CGContextStrokePath(UIGraphicsGetCurrentContext()); } - (void)dealloc { [super dealloc]; } @end #import <UIKit/UIKit.h> #import "Word.h" @interface WordView : UIView { Word *gameWord; } @property (nonatomic, retain) Word *gameWord; @end @implementation WordView @synthesize gameWord; - (id)initWithFrame:(CGRect)frame { if (self = [super initWithFrame:frame]) { self.backgroundColor = [UIColor whiteColor]; LetterLabel *label = [[LetterLabel alloc] initWithFrame:CGRectMake(0, 0, 20, 30)]; label.backgroundColor = [UIColor cyanColor]; label.textAlignment = UITextAlignmentCenter; label.textColor = [UIColor blackColor]; [label setText:@"t"]; [self addSubview:label]; } return self; } - (void)drawRect:(CGRect)rect { // Drawing code } - (void)dealloc { [gameWord release]; [super dealloc]; } @end

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  • Lighting does not work with gluSphere

    - by badcodenotreat
    This is a simple issue that I'm somewhat ashamed to ask for help on. I'm making a simple call to gluSphere to render a sphere, however, it does not light properly even though I'm pretty sure I added the normals and lighting correctly. If, however, I add a texture, the model lights normally, except it seems to be always SMOOTH, and I cannot change it to flat. This is the lighting code in my init() function: gl.glLightfv( GL.GL_LIGHT0, GL.GL_AMBIENT , AMBIENT_LIGHT, 0 ); gl.glLightfv( GL.GL_LIGHT0, GL.GL_DIFFUSE , DIFFUSE_LIGHT, 0 ); gl.glLightfv( GL.GL_LIGHT0, GL.GL_POSITION, light_pos , 0 ); gl.glEnable ( GL.GL_LIGHT0 ); gl.glEnable ( GL.GL_LIGHTING ); this is my sphere code in my display() function: gl.glColor3d(1.0, 1.0, 1.0); glu.gluQuadricDrawStyle (quad, GLU.GLU_FILL); glu.gluQuadricNormals (quad, GLU.GLU_FLAT); glu.gluQuadricOrientation(quad, GLU.GLU_OUTSIDE); glu.gluSphere(quad, 1.0, lat, lon); Please advise.

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  • Can't block capslock with CGEventTap

    - by Thor Frølich
    I'm using Quartz CGEventTap in an attempt to globally intercept capslock presses and block them (to have them do something useful instead). I succesfully detect capslock presses but have so far been unable to block them. My code (originating from this stackoverflow answer) is something like this: eventTap = CGEventTapCreate(kCGHIDEventTap, kCGTailAppendEventTap, kCGEventTapOptionDefault, eventMask, myCGEventCallback, &oldFlags); runLoopSource = CFMachPortCreateRunLoopSource(kCFAllocatorDefault, eventTap, 0); CFRunLoopAddSource(CFRunLoopGetCurrent(), runLoopSource, kCFRunLoopCommonModes); CGEventTapEnable(eventTap, true); CGEventRef myCGEventCallback(CGEventTapProxy proxy, CGEventType type, CGEventRef theEvent, void *refcon) { CGEventFlags *oldFlags = (CGEventFlags *)refcon; switch (type) { case kCGEventFlagsChanged: { CGEventFlags newFlags = CGEventGetFlags(theEvent); CGEventFlags changedFlags = *oldFlags ^ newFlags; *oldFlags = newFlags; if (changedFlags == 65536) { NSLog(@"Capslock pressed. Let's not return the event"); return NULL; } break; } default: break; } NSLog(@"Different modifier than capslock. Returning the event"); return theEvent; } If I understand correctly returning NULL should effectively block the keypress from propagating. Indeed it also does for "normal" keyup and -down events. However capslock toggles regardless. Any ideas why that is? Am I making incorrect assumptions? And/or how can I do things differently to achieve my goal? Thanks, Thor

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  • draw ios quartz 2d path with a varying alpha component

    - by Giovanni
    Hi, I'd like to paint some Bezier curves with the alpha channel that is changing during the curve painting. Right now I'm able to draw bezier paths, with a fixed alpha channel. What I'd like to do is to draw a single bezier curve that uses a certain value of the alpha channel for the first n points of the path another, alpha value for the subsequent m points and so on. The code I'm using for drawing bezier path is: CGContextSetStrokeColorWithColor(context, curva.color.CGColor); .... CGContextAddCurveToPoint(context, cp1.x, cp1.y, cp2.x, cp2.y, endPoint.x, endPoint.y); .... CGContextStrokePath(context); Is there a way to achieve what I'm describing? Many thanks, Giovanni

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  • iPhone Rendering Question

    - by slythic
    Hi all, I'm new to iPhone/Objective-C development. I "jumped the gun" and started reading and implementing some chapters from O'Reilly's iPhone Development. I was following the ebook's code exactly and my code was generating the following error: CGContextSetFillColorWithColor: invalid context CGContextFillRects: invalid context CGContextSetFillColorWithColor: invalid context CGContextGetShouldSmoothFonts: invalid context However, when I downloaded the sample code for the same chapter the code is different. Book Code: - (void) Render { CGContextRef g = UIGraphicsGetCurrentContext(); //fill background with gray CGContextSetFillColorWithColor(g, [UIColor grayColor].CGColor); CGContextFillRect(g, CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)); //draw text in black. CGContextSetFillColorWithColor(g, [UIColor blackColor].CGColor); [@"O'Reilly Rules!" drawAtPoint:CGPointMake(10.0, 20.0) withFont:[UIFont systemFontOfSize:[UIFont systemFontSize]]]; } Actual Project Code from the website (works): - (void) Render { [self setNeedsDisplay]; //this sets up a deferred call to drawRect. } - (void)drawRect:(CGRect)rect { CGContextRef g = UIGraphicsGetCurrentContext(); //fill background with gray CGContextSetFillColorWithColor(g, [UIColor grayColor].CGColor); CGContextFillRect(g, CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)); //draw text in black. CGContextSetFillColorWithColor(g, [UIColor blackColor].CGColor); [@"O'Reilly Rules!" drawAtPoint:CGPointMake(10.0, 20.0) withFont:[UIFont systemFontOfSize:[UIFont systemFontSize]]]; } What is it about these lines of code that make the app render correctly? - (void) Render { [self setNeedsDisplay]; //this sets up a deferred call to drawRect. } - (void)drawRect:(CGRect)rect { Thanks in advance for helping out a newbie!

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  • masking a UIImage

    - by iworkinprogress
    I'm working on an app that can change the borders or a rectangular UIImage. The borders will vary, but will look like the UIImage was cut out with scissors, or something to that affect. What is the best way to do this? My first thought is to prep a bunch of transparent PNGs with the correct border effect I'm looking for, and then somehow use that as a mask for my UIImage. Is this the right path? Or is there a more flexible programmatic way to do this?

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  • iPhone: How to Maintain Original Image Size Thoughout Image Edits

    - by maddy
    hi, I am developing an iPhone app that resizes and merges images. I want to select two photos of size 1600x1200 from photo library and then merge both into a single image and save that new image back to the photo library. However, I can't get the right size for the merged image. I take two image views of frame 320x480 and set the view's image to my imported images. After manipulating the images (zooming, cropping, rotating), I then save the image to album. When I check the image size it shows 600x800. How do I get the original size of 1600*1200? I've been stuck on this problem from two weeks! Thanks in advance.

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  • Matlab: Adding symbols to figure

    - by niko
    Hi, Below is the user interface I have created to simulate LDPC coding and decoding The code sequence is decoded iteratively by passing values between the left and right nodes through the connections. The first thing it would be good to add in order to improve visualization is to add arrows to the connections in the direction of passing values. The alternative is to draw a bigger arrow at the top of the connection showing the direction. Another thing I would like to do is displaying the current mathematical operation below the connection (in this example c * H'). What I don't know how to do is displaying special characters and mathematical symbols and other kinds of text such as subscript and superscript in the figure (for example sum sign and subscript "T" instead of sign ="'" to indicate transposed matrix). I would be very thankful if anyone could point to any useful resources for the questions above or show the solution. Thank you.

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  • How do I use texture-mapping in a simple ray tracer?

    - by fastrack20
    I am attempting to add features to a ray tracer in C++. Namely, I am trying to add texture mapping to the spheres. For simplicity, I am using an array to store the texture data. I obtained the texture data by using a hex editor and copying the correct byte values into an array in my code. This was just for my testing purposes. When the values of this array correspond to an image that is simply red, it appears to work close to what is expected except there is no shading. The bottom right of the image shows what a correct sphere should look like. This sphere's colour using one set colour, not a texture map. Another problem is that when the texture map is of something other than just one colour pixels, it turns white. My test image is a picture of water, and when it maps, it shows only one ring of bluish pixels surrounding the white colour. When this is done, it simply appears as this: Here are a few code snippets: Color getColor(const Object *object,const Ray *ray, float *t) { if (object->materialType == TEXTDIF || object->materialType == TEXTMATTE) { float distance = *t; Point pnt = ray->origin + ray->direction * distance; Point oc = object->center; Vector ve = Point(oc.x,oc.y,oc.z+1) - oc; Normalize(&ve); Vector vn = Point(oc.x,oc.y+1,oc.z) - oc; Normalize(&vn); Vector vp = pnt - oc; Normalize(&vp); double phi = acos(-vn.dot(vp)); float v = phi / M_PI; float u; float num1 = (float)acos(vp.dot(ve)); float num = (num1 /(float) sin(phi)); float theta = num /(float) (2 * M_PI); if (theta < 0 || theta == NAN) {theta = 0;} if (vn.cross(ve).dot(vp) > 0) { u = theta; } else { u = 1 - theta; } int x = (u * IMAGE_WIDTH) -1; int y = (v * IMAGE_WIDTH) -1; int p = (y * IMAGE_WIDTH + x)*3; return Color(TEXT_DATA[p+2],TEXT_DATA[p+1],TEXT_DATA[p]); } else { return object->color; } }; I call the colour code here in Trace: if (object->materialType == MATTE) return getColor(object, ray, &t); Ray shadowRay; int isInShadow = 0; shadowRay.origin.x = pHit.x + nHit.x * bias; shadowRay.origin.y = pHit.y + nHit.y * bias; shadowRay.origin.z = pHit.z + nHit.z * bias; shadowRay.direction = light->object->center - pHit; float len = shadowRay.direction.length(); Normalize(&shadowRay.direction); float LdotN = shadowRay.direction.dot(nHit); if (LdotN < 0) return 0; Color lightColor = light->object->color; for (int k = 0; k < numObjects; k++) { if (Intersect(objects[k], &shadowRay, &t) && !objects[k]->isLight) { if (objects[k]->materialType == GLASS) lightColor *= getColor(objects[k], &shadowRay, &t); // attenuate light color by glass color else isInShadow = 1; break; } } lightColor *= 1.f/(len*len); return (isInShadow) ? 0 : getColor(object, &shadowRay, &t) * lightColor * LdotN; } I left out the rest of the code as to not bog down the post, but it can be seen here. Any help is greatly appreciated. The only portion not included in the code, is where I define the texture data, which as I said, is simply taken straight from a bitmap file of the above image. Thanks.

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  • How to- NSAttributedString to CGImageRef

    - by kroko
    Hello! I'm writing a QuickLook plugin. Well, everything works. Just want to try it make better ;). Thus the question. Here is a function that returns thumbnail image and that I'm using now. QLThumbnailRequestSetImageWithData( QLThumbnailRequestRef thumbnail, CFDataRef data, CFDictionaryRef properties); ); http://developer.apple.com/mac/library/documentation/UserExperience/Reference/QLThumbnailRequest_Ref/Reference/reference.html#//apple_ref/c/func/QLThumbnailRequestSetImageWithData Right now I'm creating a TIFF - encapsulated it into NSData. An example // Setting CFDataRef CGSize thumbnailMaxSize = QLThumbnailRequestGetMaximumSize(thumbnail); NSMutableAttributedString *attributedString = [[[NSMutableAttributedString alloc] initWithString:@"dummy" attributes:[NSDictionary dictionaryWithObjectsAndKeys: [NSFont fontWithName:@"Monaco" size:10], NSFontAttributeName, [NSColor colorWithCalibratedRed:0.0 green:0.0 blue:0.0 alpha:1.0], NSForegroundColorAttributeName, nil] ] autorelease]; NSImage *thumbnailImage = [[[NSImage alloc] initWithSize:NSMakeSize(thumbnailMaxSize.width, thumbnailMaxSize.height)] autorelease]; [thumbnailImage lockFocus]; [[NSColor whiteColor] set]; NSRectFill(NSMakeRect(0, 0, thumbnailMaxSize.width, thumbnailMaxSize.height)); [attributedString drawInRect:NSMakeRect(0, 0, thumbnailMaxSize.width, thumbnailMaxSize.height)]; [thumbnailImage unlockFocus]; (CFDataRef)[thumbnailImage TIFFRepresentation]; // This is data // Setting CFDictionaryRef (CFDictionaryRef)[NSDictionary dictionaryWithObjectsAndKeys:@"kUTTypeTIFF", (NSString *)kCGImageSourceTypeIdentifierHint, nil ]; // this is properties However QuickLook provides another function to return thumbnail image, namely QLThumbnailRequestSetImage( QLThumbnailRequestRef thumbnail, CGImageRef image, CFDictionaryRef properties); ); http://developer.apple.com/mac/library/documentation/UserExperience/Reference/QLThumbnailRequest_Ref/Reference/reference.html#//apple_ref/c/func/QLThumbnailRequestSetImage I have a feeling that passing CGImage to the QL instead of TIFF data would help in speeding things up. However- I have never worked with CG context before. I know, the documentation is there :), but anyways- could anyone give an example how to turn that NSAttributed string into CGImageRef. An example is worth 10 times reading the documentation ;) Any help appreciated. Thanks in advance!

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