checkpoint_0_shaderplace.glsl

#ifdef GL_ES
precision mediump float;
#endif

uniform vec2 u_resolution;
uniform float u_time;
uniform float u_vol;

void main() {

    vec2 pos = ((gl_FragCoord.xy/u_resolution) - 0.5)*2.0; // origin is in center
    // who remembers SOH CAH TOA ?
    // tan, given an angle will return the ratio
    // so if we only have the ratio of position
    // we use atan to get the angle
    float angle = atan(pos.y,pos.x);

    float r = sin(angle + u_time); 
    // sin returns a number from -1 to 1, and colors are from 0 to 1, so thats 
    // why you only see red on the screen half the time. the angle goes around
    // the screen, adding time moves it clockwise
	
	float g = cos(length(pos*10.)-u_time);
	// the distance (aka length) from the center put in a cos, subtracting 
	// time moves the circles out. 
	
	float b = cos(angle+ cos(length(pos*15.)) + u_time); 
	// this combines what we learned in the red and green channels
	// angle is going through a cos and so is the length, so we see the 
	// blue channel oscillating in both dimensions the polar coordinates give us
	
    vec4 color = vec4(r,g,b,1);
    
    gl_FragColor = color;
}