git.sesse.net Git - movit/blob - fft_pass_effect.frag

   1 // DIRECTION_VERTICAL will be #defined to 1 if we are doing a vertical FFT,
   2 // and 0 otherwise.
   3
   4 uniform float PREFIX(num_repeats);
   5 uniform sampler2D PREFIX(support_tex);
   6
   7 vec4 FUNCNAME(vec2 tc) {
   8 #if DIRECTION_VERTICAL
   9         vec4 support = texture2D(PREFIX(support_tex), vec2(tc.y * PREFIX(num_repeats), 0.0));
  10         vec4 c1 = INPUT(vec2(tc.x, tc.y + support.x));
  11         vec4 c2 = INPUT(vec2(tc.x, tc.y + support.y));
  12 #else
  13         vec4 support = texture2D(PREFIX(support_tex), vec2(tc.x * PREFIX(num_repeats), 0.0));
  14         vec4 c1 = INPUT(vec2(tc.x + support.x, tc.y));
  15         vec4 c2 = INPUT(vec2(tc.x + support.y, tc.y));
  16 #endif
  17         // Two complex additions and multiplications in parallel; essentially
  18         //
  19         //   result.xy = c1.xy + twiddle * c2.xy
  20         //   result.zw = c1.zw + twiddle * c2.zw
  21         //
  22         // where * is complex multiplication.
  23         return c1 + support.z * c2 + support.w * vec4(-c2.y, c2.x, -c2.w, c2.z);
  24 }