third_party/gles2_book/Chapter_13/ProceduralTextures/checker.fs

   1 #ifdef GL_ES
   2 precision highp float;
   3 #endif
   4
   5 uniform int     frequency;
   6 uniform vec4    color0;
   7 uniform vec4    color1;
   8
   9 varying vec2    v_st;
  10
  11 void
  12 main()
  13 {
  14     float   s, t, delta;
  15
  16     s = mod(floor(v_st.x * float(frequency * 2)), 2.0);
  17     t = mod(floor(v_st.y * float(frequency * 2)), 2.0);
  18     delta = abs(s - t);
  19
  20     gl_FragColor = mix(color1, color0, delta);
  21 }