shadermeh/shaders/spectrum.frag

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/*
2D LED Spectrum - Visualiser
Based on Led Spectrum Analyser by: simesgreen - 27th February, 2013 https://www.shadertoy.com/view/Msl3zr
2D LED Spectrum by: uNiversal - 27th May, 2015
Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
*/
void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
// create pixel coordinates
vec2 uv = fragCoord.xy / iResolution.xy;
// quantize coordinates
const float bands = 30.0;
const float segs = 40.0;
vec2 p;
p.x = floor(uv.x*bands)/bands;
p.y = floor(uv.y*segs)/segs;
// read frequency data from first row of texture
float fft = texture( iChannel0, vec2(p.x,0.0) ).x;
// led color
vec3 color = mix(vec3(0.0, 2.0, 0.0), vec3(2.0, 0.0, 0.0), sqrt(uv.y));
// mask for bar graph
float mask = (p.y < fft) ? 1.0 : 0.1;
// led shape
vec2 d = fract((uv - p) *vec2(bands, segs)) - 0.5;
float led = smoothstep(0.5, 0.35, abs(d.x)) *
smoothstep(0.5, 0.35, abs(d.y));
vec3 ledColor = led*color*mask;
// output final color
fragColor = vec4(ledColor, 1.0);
}