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adapt temporal slide shader into processing; ouch !!

[1 Reply]
- 16-Feb-2013 09:46 AM
- Forum: Core Library Questions
hello all,
I try to adapt a temporal slide shader into processing.
I'm pretty newbie to processing, and to the shader world.
The shader should do really cool effects of fading frames from camera for instance.
But still black screen...

here's the code pde, and fragment code:
1. import processing.video.*;
  PShader slide;
  Capture cam;
  void setup() {
  size(320, 240, P2D);
  cam = new Capture(this, 320, 240);
  textureWrap(CLAMP);
  slide = loadShader( "slide-frag.glsl");
  cam.start(); slide.set("tex0", cam);
  }
  
  void draw() {
  println(frameRate);
  if (cam.available())
  {
  cam.read();
  }
  slide.set("slide_down", 20);
  shader(slide);
  image(cam, 0, 0,width,height);
  
  }
here's the slide-frag.glsl code:
1. #ifdef GL_ES
  precision mediump float;
  precision mediump int;
  #endi
  
  uniform float slide_up;
  uniform float slide_down;
  
  varying vec2 texcoord0;
  varying vec2 texcoord1;
  
  uniform sampler2D tex0;
  uniform sampler2D tex1;
  
  void main(void)
  {
      vec4 su, sd, up, down, amount;
  
      // sample inputs at texcoords
      vec4 input0 = texture2DRect(tex0, texcoord0);
      vec4 input1 = texture2DRect(tex1, texcoord1);
  
      // get contribution
      amount.x = input0.x > input1.x ? 1.0 : 0.0;
      amount.y = input0.y > input1.y ? 1.0 : 0.0;
      amount.z = input0.z > input1.z ? 1.0 : 0.0;
      amount.w = input0.w > input1.w ? 1.0 : 0.0;
  
      // calculate slide down
      float d = max(1.0, abs(slide_down));
      sd = vec4(1.0 / d);
      down = input1 + ((input0 - input1) * sd);
  
      // calculate slide up
      float u = max(1.0, abs(slide_up));
      su = vec4(1.0 / u);
      up = input1 + ((input0 - input1) * su);
  
      // mix between down and up
      gl_FragColor = mix(down, up, amount);
  }
any help would be appreciated, thank you !!

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