glsl常用方法收集

RGB 转 HSB

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);
}

HSB 转 RGB

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);
}

像素坐标转极坐标

    // 代码仅供参考
    vec2 st = gl_FragCoord.xy/u_resolution;
    vec3 color = vec3(0.0);

    // Use polar coordinates instead of cartesian
    vec2 toCenter = vec2(0.5)-st;
    float angle = atan(toCenter.y,toCenter.x);
    float radius = length(toCenter)*2.0;

    // Map the angle (-PI to PI) to the Hue (from 0 to 1)
    // and the Saturation to the radius
    color = hsb2rgb(vec3((angle/TWO_PI)+0.5,radius,1.0));

…… 持续更新