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Index › Programming Questions & Help › OpenGL and 3D Libraries › upscaling images with/without opengl
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upscaling images with/without opengl (Read 860 times)
holst
upscaling images with/without opengl
Feb 28th, 2006, 4:27pm  

First of all, great software! Great also for looping trough individual pixels, which is extremely cpu intensive (read: impossible) with actionscript. I noticed the bug about the pixel operations (pixel[]/set()/get()) that have been broken for opengl in the beta-release. Fixing this is said to have a low priority since pixel operations did not benefit from the opengl renderer. I receive 160-120 matrixes from eyesweb via a socket connection, and want to upscale them to 800-600 (image(0,0,800,600)). The upscaling alone takes about 80 % of my cpu (amd athlon 2800) without opengl, and almost nothing with opengl hardware acceleration. The problem is that I can't make the matrix into an image without using pixels[]. Does anyone know another way for getting fullscreen images, or will there be a fix in the near future?
Regards, holst
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TomC
Re: upscaling images with/without opengl
Reply #1 - Feb 28th, 2006, 4:55pm  
Making a 160x120 PImage and updating it using pixels should work with OPENGL. If you create the PImage in setup() and update it in draw() it should work pretty quickly.  

I don't know about eyesweb sockets but depending on how often you receive data from there and how that code works, you might not want to convert from a matrix to an image every frame.

Here's an example:

Code:


import processing.opengl.*;

// global image for reuse in draw
PImage img;

void setup() {

  size(800,600,OPENGL);
 
  // initialise image once only
  img = new PImage(160,120);

  // for this example, use HSB not RGB...
  colorMode(HSB);
}

void draw() {

  background(0);

  // loop through all pixels in img
  img.loadPixels();
  for (int i = 0; i < img.pixels.length; i++) {
    // work out x and y of pixels[i]
    float x = i%img.width;
    float y = i/img.width;
    // work out angle from mouse to screen location of pixels[i]
    float ang = atan2(y-(img.height*mouseY/height),x-(img.width*mouseX/width));
    // colour pixels[i] according to angle
    img.pixels[i] = color(255*(ang+PI)/TWO_PI,255,255);
  }
  img.updatePixels();

  // draw img full screen
  image(img,0,0,width,height);

}

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holst
Re: upscaling images with/without opengl
Reply #2 - Feb 28th, 2006, 6:12pm  
Thnx TomC,
your example works. I got confused because pixels[] seems to work with P3D and not with OPENGL, and img.pixels[] seems to work with both. (is that correct?) Also, with P3D I do not need to call img.loadPixels[] and img.updatePixels[] before calling image(img,0,0,800,600), and with OPENGL I do. (also correct?) I forgot to change that when switching render mode.
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TomC
Re: upscaling images with/without opengl
Reply #3 - Feb 28th, 2006, 6:43pm  
Yes, that's right on both counts as I understand it.  The bug (91) is with pixels, copy, get() and set() for the main applet.  It should be OK with images if you remember to do load and updatePixels.
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