progs/glsl/CH06-brick.frag

   1 //
   2 // Fragment shader for procedural bricks
   3 //
   4 // Authors: Dave Baldwin, Steve Koren, Randi Rost
   5 //          based on a shader by Darwyn Peachey
   6 //
   7 // Copyright (c) 2002-2006 3Dlabs Inc. Ltd.
   8 //
   9 // See 3Dlabs-License.txt for license information
  10 //
  11
  12 uniform vec3  BrickColor, MortarColor;
  13 uniform vec2  BrickSize;
  14 uniform vec2  BrickPct;
  15
  16 varying vec2  MCposition;
  17 varying float LightIntensity;
  18
  19 void main()
  20 {
  21     vec3  color;
  22     vec2  position, useBrick;
  23
  24     position = MCposition / BrickSize;
  25
  26     if (fract(position.y * 0.5) > 0.5)
  27         position.x += 0.5;
  28
  29     position = fract(position);
  30
  31     useBrick = step(position, BrickPct);
  32
  33     color  = mix(MortarColor, BrickColor, useBrick.x * useBrick.y);
  34     color *= LightIntensity;
  35     gl_FragColor = vec4(color, 1.0);
  36 }