1 // DIRECTION_VERTICAL will be #defined to 1 if we are doing a vertical FFT,
5 // uniform float PREFIX(num_repeats);
6 // uniform sampler2D PREFIX(support_tex);
8 vec4 FUNCNAME(vec2 tc) {
10 vec4 support = tex2D(PREFIX(support_tex), vec2(tc.y * PREFIX(num_repeats), 0.0));
11 vec4 c1 = INPUT(vec2(tc.x, tc.y + support.x));
12 vec4 c2 = INPUT(vec2(tc.x, tc.y + support.y));
14 vec4 support = tex2D(PREFIX(support_tex), vec2(tc.x * PREFIX(num_repeats), 0.0));
15 vec4 c1 = INPUT(vec2(tc.x + support.x, tc.y));
16 vec4 c2 = INPUT(vec2(tc.x + support.y, tc.y));
18 // Two complex additions and multiplications in parallel; essentially
20 // result.xy = c1.xy + twiddle * c2.xy
21 // result.zw = c1.zw + twiddle * c2.zw
23 // where * is complex multiplication.
24 return c1 + support.z * c2 + support.w * vec4(-c2.y, c2.x, -c2.w, c2.z);
27 #undef DIRECTION_VERTICAL