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  • In OpenGL vertex shader, gl_Position doesn't get homogenized..

    - by KJ
    Hi everyone, I was expecting gl_Position to automatically get homogenized (divided by w), but it seems not working.. Why do the followings make different results? 1) void main() { vec4 p; ... omitted ... gl_Position = projectionMatrix * p; } 2) ... same as above ... p = projectionMatrix * p; gl_Position = p / p.w; I think the two are supposed to generate the same results, but it seems it's not the case. 1 doesn't work while 2 is working as expected.. Could it possibly be a precision problem? Am I missing something? This is driving me almost crazy.. helps needed. Many thanks in advance!

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  • Super wide, but not so tall, bitmap?

    - by Erik Karlsson
    Howdy folks. Is there any way to create a more space/resource efficient bitmap? Currently i try to render a file, approx 800 px high but around 720000px wide. It crashes my application, presumebly because of the share memory-size of the bitmap. Can i do it more efficient, like creating it as an gif directly and not later when i save it? I try to save a series of lines/rectangles from a real world reading, and i want it to be 1px per 1/100th of a second. Any input? And btw, i never manage to ogon using google open id : /

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  • How do I prevent jagged edges alongside the surfaces of my 3d model?

    - by badcodenotreat
    Lets say I've implemented in openGL a crude model viewer with shading which renders a series of blocks, such that I have something that looks like this. http://i.imgur.com/TsF7K.jpg Whenever I rotate my model to the side, it causes an unwanted jagged effect along any surface with a steep viewing angle. http://i.imgur.com/Bgl9o.jpg I'm pretty sure this is due to the polygon offset I used to prevent z-fighting between the model and the wireframe, however I'm not able to find the factor/unit parameters in openGL which prevent this unwanted effect. what are the best values of factor and unit for glPolygonOffset to prevent this? would implementing anti-aliasing alleviate the problem? is the trade off in performance trivial/significant? is this perhaps a shading issue? should i try a solution along this line of thought?

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  • Easy Flood Fill

    - by Jimmy
    Some advice, please. I'm just starting out in C#. I've managed to get some shapes created on a Windows form, and now I'd like to fill them with color. In the old C++ I studied years ago, there was a floodfill function that was really easy. It has been an unpleasant realization to find there's not a similar method available in regular old C#. Does anyone have advice for me, or some code, so I can implement filling without understanding GDI+, DirectX, or rest of the avalanche of acronyms that I've run into by researching this on the web? I need to fill irregular shapes, bounded by a certain color. Gradient and transparency control would be nice, but I'd settle for plain old solid fill right now, just to get a modicom of control over this. Any help, code or advice would be really appreciated.

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  • How well are SVG filter elements defined?

    - by Peter Becker
    We are considering using SVG filters as part of our toolchain, serving the SVG to browsers capable of supporting it, while serving pre-rendered PNGs to other. One problem we noticed is that the rendering of the filter chains seems to be very inconsistent across renderers. When looking at the "filters01" example from the SVG specification, the rendering looks very different across the tools we tried. Chrome (5.0.307.11) failed to render the image, while other tools (Firefox 3.6, Opera 10.10, Inkscape 0.47, GIMP 2.6.7) render something vaguely similar in style to the picture in the specification, but no two are truly the same. Is that an issue of under-specification or are the tools just not there? If we would use SVG with filter effects: is there a reference tool that can give us a rendering the way it is intended by the spec?

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  • How do I draw a proper parallelogram that can be animated on iPhone?

    - by Robert Kosara
    I'm trying to do something very simple: I need some parallelograms in my program. These are attached to other objects, all of which are UIViews. It's important that I be able to animate these, since the objects they are attached to can also be animated. I've figured out how to use the transform in UIView/CALayer to do this, but the problem is that these sheared UIViews don't look very nice: there is no anti-aliasing of the edges. Is there some other way to do this? I would like to use UIViews, since I also use them for user interaction and animation is so much easier than drawing by hand. I don't want to use OpenGL for this.

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  • Auto scrolling or shifting a bitmap in .NET

    - by mikej
    I have a .NET GDI+ bitmap object (or if it makes the problem easier a WPF bitmap object) and what I want to to is shift the whole lot by dx,dy (whole pixels) and I would ideally like to do it using .NET but API calls are ok. It has to be efficient bacause its going to be called 10,000 times say with moderately large bitmaps. I have implemented a solution using DrawImage - but its slow and it halts the application for minutes while the GC cleans up the temp objects that have been used. I have also started to work on a version using ScrollDC but so far have had no luck getting it to work on the DC of the bitmap (I can make it work buy creating an API bitmap with bitmap handle, then creating a compatible DC asnd calling ScrollDC but then I have to put it back into the bitmap object). There has to be an "inplace" way of shifting a bitmap. mikej

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  • How to access pixels of an NSBitmapImageRep?

    - by Paperflyer
    I have an NSBitmapImageRep that is created like this: NSBitmapImageRep *imageRep = [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:NULL pixelsWide:waveformSize.width pixelsHigh:waveformSize.height bitsPerSample:8 samplesPerPixel:4 hasAlpha:YES isPlanar:YES colorSpaceName:NSCalibratedRGBColorSpace bytesPerRow:0 bitsPerPixel:0]; Now I want to access the pixel data so I get a pointer to the pixel planes using unsigned char *bitmapData; [imageRep getBitmapDataPlanes:&bitmapData]; According to the Documentation this returns a C array of five character pointers. But how can it do that? since the type of the argument is unsigned char **, it can only return an array of chars, but not an array of char pointers. So, this leaves me wondering how to access the individual pixels. Do you have an idea how to do that? (I know there is the method – setColor:atX:y:, but it seems to be pretty slow if invoked for every single pixel of a big bitmap.)

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  • drawing images and lines over UIScrollView

    - by Jorge
    I'm programming an app in which one of the ViewControllers is showing an UIScrollView that shows an image. I'd like to load an image (pushpin in png format) and draw it (and delete it) in some points of the UIScrollView image. I'd also would like to draw bezier paths in that image (and deleting them). I've programmed several apps but this is the first time I face graphic programming and don't know where to start from. Any suggestions? Thanks!

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  • Optimizing drawing on UITableViewCell

    - by Brian
    I am drawing content to a UITableViewCell and it is working well, but I'm trying to understand if there is a better way of doing this. Each cell has the following components: Thumbnail on the left side - could come from server so it is loaded async Title String - variable length so each cell could be different height Timestamp String Gradient background - the gradient goes from the top of the cell to the bottom and is semi-transparent so that background colors shine through with a gloss It currently works well. The drawing occurs as follows: UITableViewController inits/reuses a cell, sets needed data, and calls [cell setNeedsDisplay] The cell has a CALayer for the thumbnail - thumbnailLayer In the cell's drawRect it draws the gradient background and the two strings The cell's drawRect it then calls setIcon - which gets the thumbnail and sets the image as the contents of the thumbnailLayer. If the image is not found locally, it sets a loading image as the contents of the thumbnailLayer and asynchronously gets the thumbnail. Once the thumbnail is received, it is reset by calling setIcon again & resets the thumbnailLayer.contents This all currently works, but using Instruments I see that the thumbnail is compositing with the gradient. I have tried the following to fix this: setting the cell's backgroundView to a view whose drawRect would draw the gradient so that the cell's drawRect could draw the thumbnail and using setNeedsDisplayInRect would allow me to only redraw the thumbnail after it loaded --- but this resulted in the backgroundView's drawing (gradient) covering the cell's drawing (text). I would just draw the thumbnail in the cell's drawRect, but when setNeedsDisplay is called, drawRect will just overlap another image and the loading image may show through. I would clear the rect, but then I would have to redraw the gradient. I would try to draw the gradient in a CAGradientLayer and store a reference to it, so I can quickly redraw it, but I figured I'd have to redraw the gradient if the cell's height changes. Any ideas? I'm sure I'm missing something so any help would be great.

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  • A dynamic array of class "landmark", inside another single class "landmarks"

    - by pinnacler
    I'm working on a robot localization simulator and I created a class called "landmark". The end result is going to be a robot that is always centered and always faces the top of the screen. As it turns, the birds eye view map will rotate around the robot. To accomplish this, I'm assuming I can rotate one class and have all elements inside rotate as well. So, the landmark class has properties x,y, label, and radius. This is suppose to simulate a tree location in a forest. To test everything, I need "forest data," and I wrote a script to generate 100 trees in a 100m x 100m area. The script automatically generates values within an acceptable range for x,y, radius. The generated data is stored in an object called tempForest and is 100x3. Ideally, I want to create a class called "landmarks" (plural) that has 100 landmark instances inside. How would I instantiate 100 instances of landmark in one instance of landmarks using that randomly generated data? Ideally, I'd just type treeBeacons = landmarks(); and it would randomly populate 100 (user definable, set in config file) instances with x, y, radius data. I'm not sure how to deal with a dynamic array of class "Landmark", inside another single class "landmarks." Any ideas?

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  • QPainter paints garbage

    - by DSblizzard
    Fragment of program code: def add_link(Item0Num, Item1Num): global Mw, View # Mw - MainWindow if Item0Num != Item1Num and not link_exists(Item0Num, Item1Num): append( links_to(Item1Num), Item0Num ) append( links_from(Item0Num), Item1Num ) LinkGi = TLinkGi() Mw.Scene.addItem(LinkGi) LinkGi.setZValue(200) LinkGi.scale(1 / View.Scale, 1 / View.Scale) LinkGi.Item0Num = Item0Num LinkGi.Item1Num = Item1Num class TLinkGi(QGraphicsItem): def paint(self, Painter, StyleOptionGraphicsItem, Widget): global Mw, View Pen = QPen(Qt.black, 1) Painter.setPen(Pen) X0, Y0 = task_center(self.Item0Num) self.setPos(X0, Y0) X1, Y1 = task_center(self.Item1Num) X, Y = int( (X1 - X0) * View.Scale ), int( (Y1 - Y0) * View.Scale ) Painter.drawLine(0, 0, X, Y) #Mw.Scene.update(0, 0, Plan.Size, Plan.Size) # (1) #Mw.gvMain.repaint() # (2) def boundingRect(self): global View Rect = QRectF(0, 0, Plan.Size, Plan.Size) return Rect This paints such garbage: http://img697.imageshack.us/content_round.php?page=done&l=img697/5395/qpaintergarbage1.jpg When lines (1) and (2) are uncommented things doesn't become much better: http://img63.imageshack.us/content_round.php?page=done&l=img63/9693/qpaintergarbage0.jpg Please help me to solve this problem.

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  • Are we DELPHI, VCL or Pascal programmers?

    - by José Eduardo
    i´ve been a delphi database programmer since D2. Now i´m facing some digital imaging and 3D challenges that make me to start study OpenGL, DirectX, Color Spaces and so on. I´m really trying but nobody seems to use Delphi for this kind of stuff, just the good-old-paycheck Database programming. ok, i know that we have some very smart guys behind some clever components, some of this open-source. Is there any PhotoShop, Blender, Maya, Office, Sonar, StarCraft, Call of Dutty written in Delphi? Do i have to learn C++ to have access to zillions of books about that kind of stuff? What is the fuzz/hype behind this: int *varName = &anhoterThing? Why pointers seems to be the holy graal to this apps? I´ve downloaded MSVC++ Express and start to learn some WPF and QT integration, and i think: "Man, Delphi does this kind of stuff, with less code, less headaches, since the wheels were invented" This lead my mind to the following... Do you ever tried to write a simple notepad program using just notepad and dcc32 in Pascal/Delphi? if so embarcadero could make our beloved pascal compiler free, and sell just the ide, the vcl, the customer support ... and back to the question: Are we DELPHI, VCL or Pascal programmers?

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  • imageWithCGImage and memory

    - by Adam Ernst
    If I use [UIImage imageWithCGImage:], passing in a CGImageRef, do I then release the CGImageRef or does UIImage take care of this itself when it is deallocated? The documentation isn't entirely clear. It says "This method does not cache the image object." Originally I called CGImageRelease on the CGImageRef after passing it to imageWithCGImage:, but that caused a malloc_error_break warning in the Simulator claiming a double-free was occurring.

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  • How do I arbitrarily distort a textured polygon?

    - by Archagon
    I'd like to write a program that lets me arbitrarily distort a textured polygon by dragging its vertices. I want the texture to distort fluidly and without overlap, assuming the new polygon doesn't intersect itself. I should also be able to repeat the process with the new shape, and with a minimum amount of loss. Are there any algorithms for doing this?

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  • tangent of two circles

    - by harryovers
    Hello, I am trying to write some code that that will draw the line which is a tangent between 2 circles. so far i have been able to draw multiple circles, and lines between the centers. i have a class which stores the values used in drawing the circles (radius, position). what i need is a method in this class to find all posible tangents between 2 circles. any help would be great. this is what i have so far (it could very well be a load of rubbish) public static Vector2[] Tangents(circle c1, circle c2) { if (c2.radius > c1.radius) { circle temp = c1; c1 = c2; c2 = temp; } circle c0 = new circle(c1.radius - c2.radius, c1.center); Vector2[] tans = new Vector2[2]; Vector2 dir = _point - _center; float len = (float)Math.Sqrt((dir.X * dir.X) + (dir.Y * dir.Y)); float angle = (float)Math.Atan2(dir.X, dir.Y); float tan_length = (float)Math.Sqrt((len * len) - (_radius * _radius)); float tan_angle = (float)Math.Asin(_radius / len); tans[0] = new Vector2((float)Math.Cos(angle + tan_angle), (float)Math.Sin(angle + tan_angle)); tans[1] = new Vector2((float)Math.Cos(angle - tan_angle), (float)Math.Sin(angle - tan_angle)); Vector2 dir0 = c0.center - tans[0]; Vector2 dir1 = c0.center - tans[1]; Vector2 tan00 = Vector2.Add(Vector2.Multiply(tans[0], (float)c2.radius), c1.center); Vector2 tan01 = c2.center; Vector2 tan10 = Vector2.Add(Vector2.Multiply(tans[1], (float)c2.radius), c1.center); Vector2 tan11 = c2.center; }

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  • How do I remove those rotation artefacts from my CATiledLayer?

    - by Felix
    Hello all, I have a CATiledLayer into which I render content in the following method - (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx I used the QuartzDemo code to draw a pattern. This works very well until I apply a rotation transform to the layer's parentLayer (a UIView): rotated: These zigzag artefacts become worse when I start drawing lines and texts into the CATiledLayer. I applied the transform as follows (I also tried using an affine transform on the view itself): self.containerView.layer.transform = CATransform3DMakeRotation(angleRadians, 0.0f, 0.0f, 1.0f); I transform the containerView rather than the layer itself, as I have several layers in that view that I would like to rotate at the same time without changing the relative positions. I did not have problems when rotating UIImageViews in the past. Is there a way that I can rotate the CATiledLayer without these problems? Any help would be greatly appreciated. Yours, Felix

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  • Rendering to a single Bitmap object from multiple threads

    - by Lee Treveil
    What im doing is rendering a number of bitmaps to a single bitmap. There could be hundreds of images and the bitmap being rendered to could be over 1000x1000 pixels. Im hoping to speed up this process by using multiple threads but since the Bitmap object is not thread-safe it cant be rendered to directly concurrently. What im thinking is to split the large bitmap into sections per cpu, render them separately then join them back together at the end. I haven't done this yet incase you guys/girls have any better suggestions. Any ideas? Thanks

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  • OpenGL Color Interpolation across vertices

    - by gutsblow
    Right now, I have more than 25 vertices that form a model. I want to interpolate color linearly between the first and last vertex. The Problem is when I write the following code glColor3f(1.0,0.0,0.0); vertex3f(1.0,1.0,1.0); vertex3f(0.9,1.0,1.0); . .`<more vertices>; glColor3f(0.0,0.0,1.0); vertex3f(0.0,0.0,0.0); All the vertices except that last one are red. Now I am wondering if there is a way to interpolate color across these vertices without me having to manually interpolate color natively (like how opengl does it automatically) at each vertex since, I will be having a lot more number of colors at various vertices. Any help would be extremely appreciated. Thank you!

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  • Video Synthesis - Making waves, pattern, gradients...

    - by Nathan
    I'm writing a program to generate some trippy visuals. My code paints each pixel with a random blue value which loops at 0.04 second intervals. for (y = 0; y < 5.5; y += 0.2) { for (x = 0; x < 7.5; x += 0.2) { b = rand() / ((double) RAND_MAX); setPixelColor(x,y,r,g,b); } } I'd like to do more than just make blue noise... but my maths is a bit rusty, and Google isn't helping me much today, so it would be great if you could share anything you know about making waves, patterns, gradient animations, etc or links to such material.

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  • Generate colors between red and green for a power meter?

    - by Simucal
    I'm writing a java game and I want to implement a power meter for how hard you are going to shoot something. I need to write a function that takes a int between 0 - 100, and based on how high that number is, it will return a color between Green (0 on the power scale) and Red (100 on the power scale). Similar to how volume controls work: What operation do I need to do on the Red, Green, and Blue components of a color to generate the colors between Green and Red? So, I could run say, getColor(80) and it will return an orangish color (its values in R, G, B) or getColor(10) which will return a more Green/Yellow rgb value. I know I need to increase components of the R, G, B values for a new color, but I don't know specifically what goes up or down as the colors shift from Green-Red. Progress: I ended up using HSV/HSB color space because I liked the gradiant better (no dark browns in the middle). The function I used was (in java): public Color getColor(double power) { double H = power * 0.4; // Hue (note 0.4 = Green, see huge chart below) double S = 0.9; // Saturation double B = 0.9; // Brightness return Color.getHSBColor((float)H, (float)S, (float)B); } Where "power" is a number between 0.0 and 1.0. 0.0 will return a bright red, 1.0 will return a bright green. Java Hue Chart: Thanks everyone for helping me with this!

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  • Equivalent of CGPoint with integers?

    - by Ivan Vucica
    Cheers, I like strict typing in C. Therefore, I don't want to store a 2D vector of floats if I specifically need integers. Is there an Apple-provided equivalent of CGPoint which stores data as integers? I've implemented my type Vector2i and its companion function Vector2iMake() à la CGPoint, but something deep in me screams that Apple was there already.

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