progs/glsl/CH06-brick.vert

   1 //
   2 // Vertex 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 LightPosition;
  13
  14 const float SpecularContribution = 0.3;
  15 const float DiffuseContribution  = 1.0 - SpecularContribution;
  16
  17 varying float LightIntensity;
  18 varying vec2  MCposition;
  19
  20 void main()
  21 {
  22     vec3 ecPosition = vec3(gl_ModelViewMatrix * gl_Vertex);
  23     vec3 tnorm      = normalize(gl_NormalMatrix * gl_Normal);
  24     vec3 lightVec   = normalize(LightPosition - ecPosition);
  25     vec3 reflectVec = reflect(-lightVec, tnorm);
  26     vec3 viewVec    = normalize(-ecPosition);
  27     float diffuse   = max(dot(lightVec, tnorm), 0.0);
  28     float spec      = 0.0;
  29
  30     if (diffuse > 0.0)
  31     {
  32         spec = max(dot(reflectVec, viewVec), 0.0);
  33         spec = pow(spec, 16.0);
  34     }
  35
  36     LightIntensity  = DiffuseContribution * diffuse +
  37                       SpecularContribution * spec;
  38
  39     MCposition      = gl_Vertex.xy;
  40     gl_Position     = ftransform();
  41 }