shaders/Phosphor-simple.shader

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <!--
   3    Plain (and obviously inaccurate) phosphor.
   4    Author: Themaister
   5    License: Public Domain
   6 -->
   7 <shader language="GLSL">
   8    <fragment filter="linear"><![CDATA[
   9       uniform sampler2D rubyTexture;
  10       uniform vec2 rubyTextureSize;
  11
  12       vec3 to_focus(float pixel)
  13       {
  14          pixel = mod(pixel + 3.0, 3.0);
  15          if (pixel >= 2.0) // Blue
  16             return vec3(pixel - 2.0, 0.0, 3.0 - pixel);
  17          else if (pixel >= 1.0) // Green
  18             return vec3(0.0, 2.0 - pixel, pixel - 1.0);
  19          else // Red
  20             return vec3(1.0 - pixel, pixel, 0.0);
  21       }
  22
  23       void main()
  24       {
  25          float y = mod(gl_TexCoord[0].y * rubyTextureSize.y, 1.0);
  26          float intensity = exp(-0.2 * y);
  27
  28          vec2 one_x = vec2(1.0 / (3.0 * rubyTextureSize.x), 0.0);
  29
  30          vec3 color = texture2D(rubyTexture, gl_TexCoord[0].xy - 0.0 * one_x).rgb;
  31          vec3 color_prev = texture2D(rubyTexture, gl_TexCoord[0].xy - 1.0 * one_x).rgb;
  32          vec3 color_prev_prev = texture2D(rubyTexture, gl_TexCoord[0].xy - 2.0 * one_x).rgb;
  33
  34          float pixel_x = 3.0 * gl_TexCoord[0].x * rubyTextureSize.x;
  35
  36          vec3 focus = to_focus(pixel_x - 0.0);
  37          vec3 focus_prev = to_focus(pixel_x - 1.0);
  38          vec3 focus_prev_prev = to_focus(pixel_x - 2.0);
  39
  40          vec3 result =
  41             0.8 * color * focus +
  42             0.6 * color_prev * focus_prev +
  43             0.3 * color_prev_prev * focus_prev_prev;
  44
  45          result = 2.3 * pow(result, vec3(1.4));
  46
  47          gl_FragColor = vec4(intensity * result, 1.0);
  48       }
  49    ]]></fragment>
  50 </shader>