HUE Shader Apply

export function applyHueShader(
    aTexture: THREE.MeshStandardMaterial,
    aHueDataObject: any
) {
    aTexture.onBeforeCompile = shader => {
        shader.uniforms.hueShift = aHueDataObject.hueShift;

        let main = "void main(";
        let out = "gl_FragColor = vec4( outgoingLight, diffuseColor.a );";

        shader.fragmentShader = shader.fragmentShader
            .split(main)
            .join(
                `
                    uniform float hueShift;

                    vec3 hsl2rgb(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);
                        return c.z + c.y * (rgb-0.5)*(1.0-abs(2.0*c.z-1.0));
                    }

                    vec3 rgb2hsl(vec3 c){
                        float cMin=min(min(c.r,c.g),c.b),
                            cMax=max(max(c.r,c.g),c.b),
                            delta=cMax-cMin;
                        vec3 hsl=vec3(0.,0.,(cMax+cMin)/2.);
                        if(delta!=0.0){ //If it has chroma and isn't gray.
                            if(hsl.z<.5){
                                hsl.y=delta/(cMax+cMin); //Saturation.
                            }else{
                                hsl.y=delta/(2.-cMax-cMin); //Saturation.
                            }
                            float deltaR=(((cMax-c.r)/6.)+(delta/2.))/delta,
                                deltaG=(((cMax-c.g)/6.)+(delta/2.))/delta,
                                deltaB=(((cMax-c.b)/6.)+(delta/2.))/delta;
                            //Hue.
                            if(c.r==cMax){
                                hsl.x=deltaB-deltaG;
                            }else if(c.g==cMax){
                                hsl.x=(1./3.)+deltaR-deltaB;
                            }else{ //if(c.b==cMax){
                                hsl.x=(2./3.)+deltaG-deltaR;
                            }
                            hsl.x=fract(hsl.x);
                        }
                        return hsl;
                    }

                ` + main
            )
            .split(out)
            .join(
                out +
                `
                        vec3 hsl = rgb2hsl(gl_FragColor.rgb);
                        hsl.x = fract(hsl.x + hueShift);
                        gl_FragColor.rgb = hsl2rgb(hsl);
                    `
            );
    };
}