gradientShiftingFromUpperLeftCorner.frag

#ifdef GL_ES
precision mediump float;
#endif

#define PI 3.14159265359

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

vec3 colorA = vec3(0.0157, 0.1412, 0.1451);
vec3 colorB = vec3(0.6353, 0.5529, 0.5529);

float plot(vec2 st, float pct) {
    return smoothstep(pct - 0.01, pct, st.y) -
        smoothstep(pct, pct + 0.01, st.y);
}

void main() {
    vec2 st = gl_FragCoord.xy / u_resolution.xy;
    vec3 color = vec3(0.0);

    vec3 pct = vec3(0);

    // float rShifttx = (sin(u_time * .9) + 1.) / 2.;
    // float rShiftx = smoothstep(0., rShifttx, st.x) - smoothstep(rShifttx, 1., st.x);
    // float rShiftty = (sin(u_time * 1.15) + 1.) / 2.;
    // float rShifty = smoothstep(0., rShiftty, st.y) - smoothstep(rShiftty, 1., st.y);
    float rShifttxy = (sin(u_time * 1.15) + 1.) / 2.;
    float rShiftxy = smoothstep(0., rShifttxy, mix(st.x, st.y, rShifttxy)) - smoothstep(rShifttxy, 1., mix(st.x, st.y, rShifttxy));
    pct.r = sin(rShiftxy * PI / 2.);
    // float gShifttx = (sin(u_time) + 1.) / 2.;
    // float gShiftx = smoothstep(0., gShifttx, st.x) - smoothstep(gShifttx, 1., st.x);
    // float gShiftty = (sin(u_time * 1.32) + 1.) / 2.;
    // float gShifty = smoothstep(0., gShiftty, st.y) - smoothstep(gShiftty, 1., st.y);
    float gShifttxy = (sin(u_time * 1.03) + 1.) / 2.;
    float gShiftxy = smoothstep(0., gShifttxy, mix(st.x, st.y, gShifttxy)) - smoothstep(gShifttxy, 1., mix(st.x, st.y, gShifttxy));
    pct.g = sin(gShiftxy * PI / 2.);
    // float bShifttx = (sin(u_time * 1.2) + 1.) / 2.;
    // float bShiftx = smoothstep(0., bShifttx, st.x) - smoothstep(bShifttx, 1., st.x);
    // float bShiftty = (sin(u_time * .83) + 1.) / 2.;
    // float bShifty = smoothstep(0., bShiftty, st.y) - smoothstep(bShiftty, 1., st.y);
    float bShifttxy = (sin(u_time * .98) + 1.) / 2.;
    float bShiftxy = smoothstep(0., bShifttxy, mix(st.x, st.y, bShifttxy)) - smoothstep(bShifttxy, 1., mix(st.x, st.y, bShifttxy));
    pct.b = sin(bShiftxy * PI / 2.);
    color = mix(colorA, colorB, pct);

    // Plot transition lines for each channel
    // color = mix(color,vec3(1.0,0.0,0.0),plot(st,pct.r));
    // color = mix(color,vec3(0.0,1.0,0.0),plot(st,pct.g));
    // color = mix(color,vec3(0.0,0.0,1.0),plot(st,pct.b));

    gl_FragColor = vec4(color, 1.0);
}