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rainbowHueHSB.glsl
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rainbowHueHSB.glsl
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#ifdef GL_ES
precision mediump float;
#endif
uniform vec2 u_resolution;
uniform float u_time;
vec3 rgb2hsb( in vec3 c ){
vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
vec4 p = mix(vec4(c.bg, K.wz),
vec4(c.gb, K.xy),
step(c.b, c.g));
vec4 q = mix(vec4(p.xyw, c.r),
vec4(c.r, p.yzx),
step(p.x, c.r));
float d = q.x - min(q.w, q.y);
float e = 1.0e-10;
return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + e)),
d / (q.x + e),
q.x);
}
// Function from Iñigo Quiles
// https://www.shadertoy.com/view/MsS3Wc
vec3 hsb2rgb( in vec3 c ){
vec3 rgb = clamp(abs(mod(c.x*6.0+vec3(0.0,4.0,2.0),
6.0)-3.0)-1.0,
0.0,
1.0 );
rgb = rgb*rgb*(3.0-2.0*rgb);
return c.z * mix(vec3(1.0), rgb, c.y);
}
void main(){
vec2 st = gl_FragCoord.xy/u_resolution.xy;
vec3 color = vec3(0.0);
// We map x (0.0 - 1.0) to the hue (0.0 - 1.0)
// And the y (0.0 - 1.0) to the brightness
// color = hsb2rgb(vec3(st.x,1.0,1.0-st.y));
color = hsb2rgb(vec3(st.x,1.0,st.y));
gl_FragColor = vec4(color,1.0);
}