Gradient #2

// Author: Jeremy Rotsztain
// Title: Gradient#2
// Edit：Qinxinrui Zhu

#ifdef GL_ES
precision mediump float;
#endif

uniform vec2 u_resolution;
uniform vec2 u_mouse;
uniform float u_time;

#define PI 3.1415926535

//  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(8.522,1.906,0.349),
                             3.256)-2.824)-1.0,
                     0.0,
                     1.0 );
    rgb = rgb*rgb*(3.0-2.0*rgb);
    return c.z * mix( vec3(0.610,0.200,1.000), rgb, c.y);
}

void main() {

    // get the xy coordinate & normalize to [0, 1] range
    vec2 st = gl_FragCoord.xy/u_resolution.xy;
    st.x *= u_resolution.x/u_resolution.y;

    // set a fill color with hsb
    // store as vec3
    vec3 hsb;
    hsb.r = st.x; // animate hue with time
    hsb.g = 1.5; // saturation
    hsb.b = 1.2; // brightness

    if( true ){
        //set basic range
    	float d = dot( st, vec2(0.940,0.940));
    	hsb.r = d;

        // Repeatedly move the graph by the X-axis
        hsb.r = fract(u_time/4.428+d);
        // Mouse movement
        hsb.g = sin(u_mouse.y/u_resolution.y+0.3);
    }

    // use custom function to translate hsv to rgb color space
    vec3 color = hsb2rgb(hsb);

    gl_FragColor = vec4(color, 1.0);
}