RainbowScreenSaver.frag

//TODO: RGB -> square instead fix RGB -> triangle
#ifdef GL_ES
precision mediump float;
#endif

const float PI = 3.14159;

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

float diatance(vec2 p1, vec2 p2){
    return (
        sqrt(
            pow((p2.y - p1.y),2.0) + pow((p2.x - p1.x),2.0)
    ));
}

//Translating Points at an angle w.r.t center point using polar form of a straight line
//Also **note :

void main() {
    vec2 res = u_resolution.xy;
    vec2 st, center = vec2(res.x/2.0,res.y/2.0);
    center.x += res.x * 0.5 * sin(u_time*3.0);center.y += res.y * 0.5 * cos(u_time*3.0);    //--rotating the center
    float dist = distance (gl_FragCoord.xy,center);                                         //   in circlular path
    float angle = atan((gl_FragCoord.y - center.y) / (gl_FragCoord.x - center.x));

    angle = (angle + u_time/2.0);   //--small increment to angle to show animation, negate addition to
                                    //  rotate counter Clockwise
    if((gl_FragCoord.x - center.x) < 0.0)   //--atan() does not return angles in 2nd and 3rd quadrant
        angle += PI;                        //  so we need to write seperate code to implement that logic
    else if((gl_FragCoord.y - center.y) < 0.0)
        angle += 2.0*PI;

    st.x = (dist * cos(angle)) / res.x; //--New color intensity after adding change to angle
    st.y = (dist * sin(angle)) / res.y;

    st.x*= 1.0+st.x;
    st.y*= 1.0+st.y;

    vec3 color;
    color = vec3(   //--passing color intensities as a multiple of positive sin() R[0,1] as a function of time to animate
        (1.0 - (st.y - st.x)*1.0)* abs(sin(u_time/2.0)),
        (1.0 - (st.x - st.y)*1.0)* abs(sin(u_time/2.0 + 2.0*PI/3.0)),
        (1.0 - ((st.x + st.y)/2.0)) * abs(sin(u_time/2.0 + 4.0*PI/3.0))
    );

    gl_FragColor = vec4(color,1.0);
}