#version 310 es
precision highp float;
precision highp int;


//vec2   iCenter = center;
//uniform float     iChannelTime[4];       // channel playback time (in seconds)
//uniform vec3      iChannelResolution[4]; // channel resolution (in pixels)
//vec4      iMouse = vec4(0,0,0,0);                // mouse pixel coords. xy: current (if MLB down),



layout(std140, binding = 0) uniform fs_ub {
    vec2 center;
    vec2 resolution;
    vec2 u_screenSize;
    vec4 u_Time;
};

float snoise(vec3 uv, float res)
{
	const vec3 s = vec3(1e0, 1e2, 1e4);
	
	uv *= res;
	
	vec3 uv0 = floor(mod(uv, res))*s;
	vec3 uv1 = floor(mod(uv+vec3(1.), res))*s;
	
	vec3 f = fract(uv); f = f*f*(3.0-2.0*f);
    
	vec4 v = vec4(uv0.x+uv0.y+uv0.z, uv1.x+uv0.y+uv0.z,
		      	  uv0.x+uv1.y+uv0.z, uv1.x+uv1.y+uv0.z);
    
	vec4 r = fract(sin(v*1e-3)*1e5);
	float r0 = mix(mix(r.x, r.y, f.x), mix(r.z, r.w, f.x), f.y);
	
	r = fract(sin((v + uv1.z - uv0.z)*1e-3)*1e5);
	float r1 = mix(mix(r.x, r.y, f.x), mix(r.z, r.w, f.x), f.y);
	
	return mix(r0, r1, f.z)*2.-1.;
}

layout(location = SV_Target0) out vec4 FragColor;

void main(void)
{
#ifdef METAL
	vec2 fragCoord = vec2(gl_FragCoord.x, u_screenSize.y - gl_FragCoord.y);
#else
	vec2 fragCoord = gl_FragCoord.xy;
#endif
    vec2   iResolution = resolution;           // viewport resolution (in pixels)
    float  iGlobalTime = u_Time[1];           // shader playback time (in seconds)

	//vec2 p = -.5 + fragCoord.xy / iResolution.xy;
    
    vec2 p = (fragCoord.xy - center.xy) / iResolution.xy;
	p.x *= iResolution.x/iResolution.y;
	
	float color = 3.0 - (3.*length(2.*p));
	
	vec3 coord = vec3(atan(p.x,p.y)/6.2832+.5, length(p)*.4, .5);
	
	for(int i = 1; i <= 3; i++)
	{
		float power = pow(2.0, float(i));
		color += (1.5 / power) * snoise(coord + vec3(0.,-iGlobalTime*.05, iGlobalTime*.01), power*16.);
	}
	FragColor = vec4( color, pow(max(color,0.),2.)*0.4, pow(max(color,0.),3.)*0.15 , 1.0);
}