Shader特效——“Cell Merge”的实现【ShaderToy】

vec3 color_bg = vec3(0.0);  
vec3 color_inner = vec3(1.0,0.9,0.16);  
vec3 color_outer = vec3(0.12,0.59,0.21);  
//vec3 color_outer = mix(color_bg, color_inner, 0.3); // also nice effect  
float timeScale = 1.0;  // 时间(速度)的缩放尺度  
float mapScale = .8;    // cell的缩放尺度  
#define cellCount 20.0  
// size in pixels inner/outer with mapscale 1.0  
// cell的内圈大小和外圈大小  
vec2 cellSize = vec2(30.0, 40.0);   
vec3 powerToColor(vec2 power)  
｛  
    // 控制颜色平滑程度  
    float tMax = pow(1.12, mapScale*3.2);  
    float tMin = 1.0 / tMax;  
    vec3 color = mix(color_bg, color_outer, smoothstep(tMin,tMax,power.y));// 外圈颜色  
    color = mix(color, color_inner, smoothstep(tMin,tMax,power.x));        // 内圈颜色  
    return color;  
｝  
vec2 getCellPower( vec2 coord, vec2 pos, vec2 size )  
｛  
    vec2 power;  
    // 当前像素离cell越远，power越小，反之越大  
    power = (size*size) / dot(coord-pos,coord-pos);  
    power *= power * sqrt(power); // ^5  
    return power;  
｝  
void mainImage( out vec4 color, in vec2 coord )  
｛  
    float T = iGlobalTime * .1 * timeScale / mapScale;  
    vec2 hRes = 0.5*iResolution.xy;  
    vec2 pos;  
    vec2 power = vec2(0.0,0.0);  
    for(float x = 1.0; x != cellCount + 1.0; ++x)  
    ｛  
        // 随机cell的位置  
        pos = hRes * vec2(sin(T*fract(0.246*x)+x*3.6)*cos(T*fract(0.374*x)-x*fract(0.6827*x))+1.,  
                          cos(T*fract(0.246*x)+x*3.6)*sin(T*fract(.374*x)-x*fract(0.6827*x))+1.);  
        // 根据当前像素的coord和cell的pos和size计算cell的power  
        power += getCellPower(coord.xy, pos, cellSize*(.75+fract(0.2834*x)*.25) / mapScale);  
    ｝  
    color.rgb = powerToColor(power);  
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