Shader Talk

nabr

Sometimes i find functions and workarounds still valid dated back in Processing Forum v1.0

• Here you can post everything you find interesting about Shaders, GLSL and Processing
  Lost &Found Github Repository, general Links, Tutorials

---

Center

A Debug Shader

Plug your formula in and see what happens next

//imagine a question mark behind every line

PShader shdr;

void setup() {
  size(640, 360, P2D);

  noStroke();
  rectMode(RADIUS);

  shdr=new PShader(this, 
    new String[]{"#version 150 \n"
    + "in vec2 position;"
    + "void main() {"
    + "gl_Position = vec4(position.xy,0.,1.);"
   + "}"
    }, new String[]{"#version 150 \n"
      + "out vec4 fragColor;"
      + "uniform vec3 iResolution;"
      + "void main() {"
      + "vec2 uvv = (gl_FragCoord.xy*2.-iResolution.xy)/iResolution.z;"
      + "float cir=.2/length(uvv);"
      + "fragColor = vec4(vec3(cir),1.);"
     +"}"
    });

  shdr.set("iResolution", new PVector(width, height, Math.min(width, height)));

  shader(shdr);
}

void draw() {
  background(0);
  rect(0, 0, width, height);
}

Lord_of_the_Galaxy

https://forum.processing.org/two/discussion/22385/reaction-diffusion-using-glsl-works-different-from-normal#latest

nabr

observation

missing pixel

what is wrong with gl_FragCoord ?

this shader works around the world, - its a processing intern issue

Update: okay, okay i was my failure i start mixing processing and jogl functions = map(mouseX, 0, width, 0, 1) :)

the shader gives the corect results

https://thebookofshaders.com/07/rect-01.jpg

so anyone who came along this post in the further, you have to convert from float into bytes or visa versa.

//Debuging shader with numbers
//forum.processing.org/two/discussion/22762/shader-talk

PShader shdr;

void setup() {
  size(640, 360, P2D);

  noStroke();
  //rectMode(RADIUS);

  shdr=new PShader(this, 
    new String[]{"#version 150 \n"
    + "in vec2 position;"
    + "void main() {"
    //NOTE I shift here in P2D mode (orthocam,viewport)
    + "gl_Position = vec4(position.xy-1,0.,1.);"
    + "}"
    }, new String[]{"#version 150 \n"
      + "out vec4 fragColor;"
      + "uniform vec3 iResolution;"
      + "uniform vec3 iMouse;"
      + "uniform vec3 iDate;"
      // Smaller Number Printing - <a href="/two/profile/P_Malin">@P_Malin</a>
      // Creative Commons CC0 1.0 Universal (CC-0)
      //shadertoy.com/view/lt3GRj
      +"float DigitBin(const in int x){"
      +   " return x==0?480599.0:x==1?139810.0:x==2?476951.0:x==3?476999.0:x==4?350020.0:x==5?464711.0:x==6?464727.0:x==7?476228.0:x==8?481111.0:x==9?481095.0:0.0;"
      +"}"
      +"float PrintValue(vec2 fragCoord, vec2 pixelCoord, vec2 fontSize, float value, float digits, float decimals) {"
      +"  vec2 charCoord = (fragCoord - pixelCoord) / fontSize;"
      +"  if(charCoord.y < 0.0 || charCoord.y >= 1.0) return 0.0;"
      +"  float bits = 0.0;"
      +"  float digitIndex1 = digits - floor(charCoord.x)+ 1.0;"
      +"  if(- digitIndex1 <= decimals) {"
      +"    float pow1 = pow(10.0, digitIndex1);"
      +"    float absValue = abs(value);"
      +"    float pivot = max(absValue, 1.5) * 10.0;"
      +"    if(pivot < pow1) {"
      +"      if(value < 0.0 && pivot >= pow1 * 0.1) bits = 1792.0;"
      +"    } else if(digitIndex1 == 0.0) {"
      +"      if(decimals > 0.0) bits = 2.0;"
      +"    } else {"
      +"      value = digitIndex1 < 0.0 ? fract(absValue) : absValue * 10.0;"
      +"      bits = DigitBin(int (mod(value / pow1, 10.0)));"
      +"    }"
      +"  }"
      +"  return floor(mod(bits / pow(2.0, floor(fract(charCoord.x) * 4.0) + floor(charCoord.y * 5.0) * 4.0), 2.0));"
      +"}"
      // Multiples of 4x5 work best
      +"vec2 fontSize = vec2(4,5) * vec2(5,3);"
      +"vec2 grid(int x, int y) { return fontSize.xx * vec2(1,ceil(fontSize.y/fontSize.x)) * vec2(x,y) + vec2(2); }"
      +"vec2 limitTo(vec2 point, int x1, int y1, int x2, int y2, int startX, int startY) {"
      +"    return clamp(point, grid(x1,y1), iResolution.xy - grid(x2,y2)) + grid(startX, startY);"
      +"}"
      +"void mainImage( out vec4 fragColor, in vec2 fragCoord ) {"
      +"  vec3 vColour = vec3(0.0);"
      +"  vec2 mouse = iMouse.xy;"
      // Print Date
      +  "vColour = mix( vColour, vec3(1.0, 1.0, 0.0), PrintValue(fragCoord, grid(0,0), fontSize, iDate.x, 5.0, 0.0));"
      + " vColour = mix( vColour, vec3(1.0, 1.0, 0.0), PrintValue(fragCoord, grid(5,0), fontSize, iDate.y , 2.0, 0.0));"
      +  "vColour = mix( vColour, vec3(1.0, 1.0, 0.0), PrintValue(fragCoord, grid(8,0), fontSize, iDate.z, 2.0, 0.0));"
      // Plot Mouse Pos
      +"  float fDistToPointB = length( vec2(mouse.x, mouse.y) - fragCoord.xy) - 4.0;"
      +"  vColour = mix(vColour, vec3(0.0, 1.0, 0.0), (1.0 - clamp(fDistToPointB, 0.0, 1.0)));"
      // Print Sin Value
      +"float fDecimalPlaces=0.;" 
      +"  if(mouse.x >= 0.0) {"
      // Print Mouse X
      +"    vec2 vPixelCoord2 = limitTo(mouse.xy, 8,2,8,4,-8,1);"
      +"    float fValue2 = mouse.x / iResolution.x;"
      +"    float fDigits = 0.0;"
      +"    fDecimalPlaces = 5.0;"
      +"    float fIsDigit2 = PrintValue(fragCoord, vPixelCoord2, fontSize, fValue2, fDigits, fDecimalPlaces);"
      +"    vColour = mix( vColour, vec3(0.0, 1.0, 0.0), fIsDigit2);"
      // Print Mouse Y
      +"    vec2 vPixelCoord3 = limitTo(mouse.xy, 8,2,8,4,0,1);"
      +"    float fValue3 = mouse.y / iResolution.y;"
      +"    fDigits = 1.0;"
      +"    float fIsDigit3 = PrintValue(fragCoord, vPixelCoord3, fontSize, fValue3, fDigits, fDecimalPlaces);"
      +"    vColour = mix( vColour, vec3(0.0, 1.0, 0.0), fIsDigit3);"
      +"}"
      +"  fragColor = vec4(vColour,1.0);"
      +"}"
      + "void main() {"
      + "vec2 uvv = (gl_FragCoord.xy*2.-iResolution.xy)/iResolution.z;"
      + "float cir=.2/length(uvv);"
      //txutxi.com/?p=182
      + "mainImage(fragColor, gl_FragCoord.xy);"

      + "fragColor += vec4(vec3(cir)/9.,1.);"
      +"}"
    });

  shdr.set("iResolution", new PVector(width, height, Math.min(width, height)));

  shdr.set("iDate", new PVector(year(), month(), day()));

  shader(shdr);
}

void draw() {
  background(0);
  println(map(mouseX, 0, width, 0, 1));

  //shdr.set("iMouse", map(mouseX, 0, width, 0, 1), map(mouseY, 0, height, 1, 0),0);

  shdr.set("iMouse", new PVector(mouseX,mouseY,0));
  rect(0, 0, width, height);
}

//vertex Shader with P3D
/*new String[]{"#version 150 \n"
+ "in vec4 position;"
+ "uniform mat4 transformMatrix;"
+ "void main() {"
+ "gl_Position = transformMatrix * position;"
+ "}"
}*/

nabr

Geforce v.s Intel

link to source files
some other: https://github.com/mc-imperial/shader-compiler-bugs

OKAY THIS WENT SOLVED

https://forum.processing.org/two/discussion/22385/reaction-diffusion-using-glsl-works-different-from-normal#latest

Lord_of_the_Galaxy

So simply put - don't rely on shaders for delicate computations and use them only for what they're meant - graphic effects.

nabr

23 Jan 2016

https://twitter.com/greggman/status/690904795104673792

nabr

PURE ART

The OpenGL 4.4 Specification Cover Page

unfortunately nothing for mac users

https://www.khronos.org/registry/OpenGL/specs/gl/glspec44.core.pdf