66 lines
1.4 KiB
GLSL
66 lines
1.4 KiB
GLSL
|
/*
|
||
|
|
|
||
|
|
Linear vs Logarithmic FFT
|
||
|
|
|
||
|
|
some good test songs:
|
||
|
|
|
||
|
|
https://soundcloud.com/kraddy/winning
|
||
|
|
https://soundcloud.com/grey-houston/soothing-piano-melody
|
||
|
|
https://soundcloud.com/pointpoint/life-in-gr
|
||
|
|
|
||
|
|
*/
|
||
|
|
|
||
|
|
//from https://stackoverflow.com/questions/35799286
|
||
|
|
float toLog(float value, float min, float max){
|
||
|
|
float exp = (value-min) / (max-min);
|
||
|
|
return min * pow(max/min, exp);
|
||
|
|
}
|
||
|
|
|
||
|
|
float getLevel(float samplePos){
|
||
|
|
// the sound texture is 512x2
|
||
|
|
int tx = int(samplePos*512.0);
|
||
|
|
// first row is frequency data (48Khz/4 in 512 texels, meaning 23 Hz per texel)
|
||
|
|
return texelFetch( iChannel0, ivec2(tx,0), 0 ).x;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
void mainImage( out vec4 fragColor, in vec2 fragCoord )
|
||
|
|
{
|
||
|
|
vec2 uv = fragCoord.xy / iResolution.xy;
|
||
|
|
|
||
|
|
float xPos;
|
||
|
|
float fft;
|
||
|
|
|
||
|
|
if (uv.y > 0.5){
|
||
|
|
|
||
|
|
//linear sampling
|
||
|
|
xPos = uv.x;
|
||
|
|
fft = getLevel(xPos);
|
||
|
|
|
||
|
|
}else{
|
||
|
|
|
||
|
|
//crop bottom and top of range
|
||
|
|
uv.x = mix(0.3,0.7, uv.x);
|
||
|
|
|
||
|
|
//logarithmic sampling
|
||
|
|
xPos = toLog(uv.x, 0.01, 1.0);
|
||
|
|
|
||
|
|
fft = getLevel(xPos);
|
||
|
|
|
||
|
|
//boost contrast
|
||
|
|
fft = pow(fft,3.0);
|
||
|
|
|
||
|
|
//boost gain
|
||
|
|
fft *= 1.5;
|
||
|
|
|
||
|
|
//contrast / brightness
|
||
|
|
float contrast = 1.4;
|
||
|
|
float brightness = 0.;
|
||
|
|
fft = (fft - 0.5) * contrast + 0.5 + brightness;
|
||
|
|
|
||
|
|
}
|
||
|
|
|
||
|
|
fragColor = vec4(vec3(fft),1.0);
|
||
|
|
|
||
|
|
}
|