Shader Mutator

precision highp float;

uniform vec2 u_resolution;
uniform float u_time;

// USAGE: rot(float angle)
#define rot(a) mat2(cos(a),-sin(a),sin(a),cos(a))
	
void main() {
	vec2 uv = (gl_FragCoord.xy - (u_resolution.xy * 0.5)) / u_resolution.y;
	vec2 uv2 = uv;
	
	uv2 *= rot(0.35);
	
	vec3 color = vec3(1.0, 0.0, 0.0);
	
	vec3 c1 = vec3(1.0, 1.0, 0.0); // yellow
	vec3 c2 = vec3(0.0, 0.6, 0.4); // green
	vec3 c3 = vec3(0.5, 0.0, 0.5); // purple
	
	// rows
	float row = fract(uv.y * 10.0 + u_time * 0.5);
	
	float diagonalRow = step(
		0.35, 
		fract(uv2.x * 50.0)
	);
	row += diagonalRow;
	
	// columns
	float col = fract(uv.x * 10.0);
	col = step(0.1, col);
	
	float diagonalCol = step(0.5, fract(uv2.y * 50.0));
	col += diagonalCol;
	
	// GREEN STRIPES
	uv.y += 1.5;
	float row2 = fract(uv.y * 5.0 + sin(u_time) * 0.03);
	row2 = smoothstep(0.2, 0.4, row2);
	row2 += diagonalCol;
	
	// PURPLE STRIPES
	uv.x += 5.3;
	float col2 = fract(uv.x * 2.0 - cos(u_time )* 0.05);
	col2 = smoothstep(0.1, 0.5, col2);
	col2 += diagonalRow;
	
	color = mix(c1, color, row);
	color = mix(c1, color, col);
	
	color = mix(c2, color, row2);
	color = mix(c3, color, col2);
	
    gl_FragColor = vec4(color, 1.0);
}