2016-05-05 19:50:03 +02:00
|
|
|
// Based on work by David Li(http://david.li/waves)
|
|
|
|
// GPU FFT using a Stockham formulation
|
|
|
|
#version 450
|
|
|
|
|
|
|
|
#ifdef GL_ES
|
|
|
|
precision mediump float;
|
|
|
|
#endif
|
|
|
|
|
|
|
|
uniform sampler2D texInput;
|
|
|
|
|
|
|
|
in vec2 texCoord;
|
2016-10-12 17:52:27 +02:00
|
|
|
out vec4 fragColor;
|
2016-05-05 19:50:03 +02:00
|
|
|
|
|
|
|
const float PI = 3.14159265359;
|
|
|
|
const float transformSize = 512.0;
|
|
|
|
const float texSize = 512.0;
|
|
|
|
const float subtransformSize = 250.0;
|
|
|
|
|
|
|
|
vec2 multiplyComplex(vec2 a, vec2 b) {
|
|
|
|
return vec2(a[0] * b[0] - a[1] * b[1], a[1] * b[0] + a[0] * b[1]);
|
|
|
|
}
|
|
|
|
|
|
|
|
void main() {
|
|
|
|
// #ifdef HORIZONTAL
|
|
|
|
// float index = texCoord.x * transformSize - 0.5;
|
|
|
|
// #else
|
|
|
|
float index = texCoord.y * transformSize - 0.5;
|
|
|
|
// #endif
|
|
|
|
|
|
|
|
float evenIndex = floor(index / subtransformSize) * (subtransformSize * 0.5) + mod(index, subtransformSize * 0.5);
|
|
|
|
|
|
|
|
//transform two complex sequences simultaneously
|
|
|
|
// #ifdef HORIZONTAL
|
|
|
|
// vec4 even = texture(texInput, vec2(evenIndex + 0.5, texCoord.y * texSize) / transformSize);
|
|
|
|
// vec4 odd = texture(texInput, vec2(evenIndex + transformSize * 0.5 + 0.5, texCoord.y * texSize) / transformSize);
|
|
|
|
// #else
|
|
|
|
// gl_FragCoord.x / texCoord.x * texSize
|
|
|
|
vec4 even = texture(texInput, vec2(texCoord.x * texSize, evenIndex + 0.5) / transformSize);
|
|
|
|
vec4 odd = texture(texInput, vec2(texCoord.x * texSize, evenIndex + transformSize * 0.5 + 0.5) / transformSize);
|
|
|
|
// #endif
|
|
|
|
|
|
|
|
float twiddleArgument = -2.0 * PI * (index / subtransformSize);
|
|
|
|
vec2 twiddle = vec2(cos(twiddleArgument), sin(twiddleArgument));
|
|
|
|
|
|
|
|
vec2 outputA = even.xy + multiplyComplex(twiddle, odd.xy);
|
|
|
|
vec2 outputB = even.zw + multiplyComplex(twiddle, odd.zw);
|
|
|
|
|
2016-10-12 17:52:27 +02:00
|
|
|
fragColor = vec4(outputA, outputB);
|
2016-05-05 19:50:03 +02:00
|
|
|
}
|