#version 450
layout(std140, set = 0, binding = 0) uniform UBO
{
   mat4 MVP;
   vec4 OutputSize;
   vec4 OriginalSize;
   vec4 SourceSize;
   uint FrameCount;
} global;

#pragma stage vertex
layout(location = 0) in vec4 Position;
layout(location = 1) in  vec2 TexCoord;
layout(location = 0) out vec2 vTexCoord;
const vec2 madd = vec2(0.5, 0.5);
void main()
{
   gl_Position = global.MVP * Position;
   vTexCoord = gl_Position.xy;
}

#pragma stage fragment
layout(location = 0) in vec2 vTexCoord;
layout(location = 0) out vec4 FragColor;

float time = float(global.FrameCount)*0.0325;
vec2 resolution = global.OutputSize.xy;
float fade = 0.45;

const float PI=3.14159265358979323846;

float speed=time*0.25;
float ground_x=0.125-0.25*cos(PI*speed*0.25);
float ground_y=0.125+0.25*sin(PI*speed*0.25);
float ground_z=speed*0.125;

vec2 rotate(vec2 k,float t)
	{
	return vec2(cos(t)*k.x-sin(t)*k.y,sin(t)*k.x+cos(t)*k.y);
	}


float scene(vec3 p)
	{
	float ball_p=0.25;
	float ball_w=ball_p*1.0;
	float ball=length(mod(p.xyz,ball_p)-ball_p*0.5)-ball_w;
	float hole_w=ball_p*0.55;
	float hole=length(mod(p.xyz,ball_p)-ball_p*0.5)-hole_w;
	float pipe_p=0.015;
	float pipe_w=pipe_p*0.42;//-0.00375*sync;
	float pipe_y=length(max(abs(mod(p.xy,pipe_p)-pipe_p*0.5)-pipe_w,0.0));
	float pipe_z=length(max(abs(mod(p.xz,pipe_p)-pipe_p*0.5)-pipe_w,0.0));
	return max(max(ball,-hole),max(pipe_y,max(pipe_y,pipe_z)));
	}

 vec3 getNormal(vec3 pos) 
 { vec3 e = vec3(0.0,0.0001,0.0); 
 return normalize(vec3( scene(pos+e.yxx)-scene(pos-e.yxx),scene(pos+e.xyx)-scene(pos-e.xyx),scene(pos+e.xxy)-scene(pos-e.xxy) ) ); 
 } 
float render_scene(vec3 ray_origin, vec3 ray_dir,float t)
{
	const int ray_n=96;
	for(int i=0;i<ray_n;i++)
	{
		
		float k=scene(ray_origin+ray_dir*t);
		t+=k*fade;
	}
	return t;	
}


void main(void)
	{
    vec2 FragCoord = vTexCoord.xy*global.OutputSize.xy;
    FragCoord.y = -FragCoord.y;

	vec2 position=(FragCoord.xy/resolution.xy);
	vec2 p=-1.0+2.0*position;
	//set up camera
	float speed=time*0.5;
	vec3 dir=normalize(vec3(p*vec2(1.0,1.0),1.));
	dir.yz=rotate(dir.yz,PI*1.0*sin(speed*0.25));		// rotation x
	dir.zx=rotate(dir.zx,PI*1.0*cos(speed*0.25));		// rotation y
	dir.xy=rotate(dir.xy,-speed*0.5);					// rotation z
	vec3 ray=vec3(ground_x,ground_y,ground_z);
	//the raymarch
	float t=0.0;
	t=render_scene(ray,dir,t);
	vec3 hit=ray+dir*t;
	t+=hit.x;
	//get normal for reflection
	vec3 n=getNormal(hit);
	//render reflection
	dir = reflect(dir,n);
	dir = normalize(refract(dir,n,.82)); 	
	t=render_scene(ray,dir,t);	
	float c=(n.x*1.0+n.y+n.z)*0.5;	
	vec3 color=vec3(0.,c*t*0.125*p.x+t*0.1,c*t*0.);
	color *= 2.412;
	FragColor=vec4(color,1.0);
}