#version 130
// make the whole shader non const after optmizing, because we set this constant before compiling

const int CurScene = 0x9; // this 0x0 has to be readded, because the optimizer throws it away





// Parameters from our host
// x: Scene+Zeit
// y: Hoehe
// z: Aspec
uniform vec4 Y; 

vec3 L;

mat2 RMat2(float a){return mat2(cos(a),sin(a),-sin(a),cos(a));}
mat2 rmx,rmx1,rmx2;

float HTorus(in vec3 z){
	return max(-z.y,max(abs(length(max(abs(z.xy)-0.5,0.0))-0.5),abs(z.z))-0.2);
}
const vec4 scale=vec4(1.385,-1.385,1.385,1.385);
float DE(in vec3 z0){
	z0.xz=z0.xz*rmx;
	vec4 z=vec4(z0,1.0);
	z.zy*=rmx1;
	float d=max(abs(z.y+1.0)-1.0,length(z.xz)-0.2);
	for(int i=0;i<4;i++){
		z.xz=abs(z.zx);
		z.x-=1.0;
		d=min(d,HTorus(z.xyz)/z.w);
		z.x-=1.0;
		z*=scale;
	}
	z.xz=z.zx;
	float s=sign(z.x);
	z.x-=1.0;
	d=min(d,HTorus(z.xyz)/z.w);
	z.x-=1.0;
	z*=scale;
	z.xz=z.xz*rmx2*s;
	z.x-=1.0;
	d=min(d,HTorus(z.xyz)/z.w);
	z.x-=1.0;
	z*=scale;
	z.y-=0.6;
	d=min(d,min(length(max(abs(z.xyz)-vec3(0.0,0.5,0.55),0.0))-0.25,
		length(max(abs(z.xyz+vec3(0.9,0.6,0.0))-vec3(0.4,-0.1,0.5),0.0))-0.4)/z.w);

	return min(d,z0.y+1.5);
}
vec4 mcol;
float CE(in vec3 z0){
	vec4 z=vec4(z0,1.0);
	z.xz=z.xz*rmx;
	z.zy*=rmx1;
	float d=max(abs(z.y+1.0)-1.0,length(z.xz)-0.2);
	for(int i=0;i<4;i++){
		z.xz=abs(z.zx);
		z.x-=1.0;
		d=min(d,HTorus(z.xyz)/z.w);
		z.x-=1.0;
		z*=scale;
	}
	z.xz=z.zx;
	float s=sign(z.x);
	z.x-=1.0;
	d=min(d,HTorus(z.xyz)/z.w);
	z.x-=1.0;
	z*=scale;
	z.xz=z.xz*rmx2*s;
	z.x-=1.0;
	d=min(d,HTorus(z.xyz)/z.w);
	z.x-=1.0;
	z*=scale;
	z.y-=0.6;
	float d2=min(length(max(abs(z.xyz)-vec3(0.0,0.5,0.55),0.0))-0.25,
		length(max(abs(z.xyz+vec3(0.9,0.6,0.0))-vec3(0.4,-0.1,0.5),0.0))-0.4)/z.w;
	float d3=z0.y+1.5;
	d=min(d,min(d2,d3));
	if(abs(d2-d)<0.001)mcol+=vec4(1.0,0.1,0.0,0.2);
	else if(abs(d3-d)<0.001){
		mcol+=vec4(0.25,0.25,0.2,0.333);
		d+=sin(-Y.x*100.0+100.0*pow(length(z0.xz),0.17))*0.01;
	}else mcol+=vec4(0.0,0.5,0.5,0.5);
	return d;
}
float linstep(float a, float b, float t){float v=(t-a)/(b-a);return clamp(v,0.,1.);}//from knighty

float rand(vec2 co){// implementation found at: lumina.sourceforge.net/Tutorials/Noise.html
	return fract(sin(dot(co*0.123,vec2(12.9898,78.233))) * 43758.5453);
}

float FuzzyShadow(vec3 ro, vec3 rd, float coneGrad, vec2 fragCoord){
	float t=0.0,d=1.0,s=1.0;
	ro+=rd*0.01;
	for(int i=0;i<32;i++){
		//if(s<0.1)continue;//uncommenting this makes shadows and reflections disappear - WTF?
		float r=t*coneGrad;//radius of cone
		d=DE(ro+rd*t)+r*0.5;
		s*=linstep(-r,r,d);
		t+=abs(d)*(0.5+0.5*rand(fragCoord.xy*vec2(i)))+0.005;
	}
	return clamp(s*0.8+0.2,0.0,1.0);
}
vec3 Background(vec3 rd){return vec3(0.8,0.9,1.0)*(0.3+0.7*pow(max(0.0,dot(rd,L)),2.0));}
vec3 FuzzyReflection(vec3 ro, vec3 rd, float coneGrad, vec2 fragCoord){
	float t=0.0,d=1.0;
	ro+=rd*0.01;
	vec4 col=vec4(0.0);
	for(int i=0;i<24;i++){
		if(col.w>0.9)continue;
		float r=t*coneGrad;//radius of cone
		d=DE(ro+rd*t)+r*0.5;
		if(d<r){
			vec3 p=ro+rd*t;
			mcol=vec4(0.0);
			vec2 v=vec2(r,0.0);//use normal deltas based on CoC radius
			vec3 N=normalize(vec3(-CE(p-v.xyy)+CE(p+v.xyy),-CE(p-v.yxy)+CE(p+v.yxy),-CE(p-v.yyx)+CE(p+v.yyx)));
			vec3 scol=mcol.rgb*0.1666*max(0.1,0.25+dot(N,L)*0.75);//do some fast light calcs (you can forget about shadow casting, too expensive)
			float alpha=(1.0-col.w)* linstep(-r,r,-d);//calculate the mix like cloud density
			col+=vec4(scol*alpha,alpha);//blend in the new color
		}
		t+=abs(d)*(0.5+0.5*rand(fragCoord.xy*vec2(i)))+0.005;
	}
	return col.rgb+Background(rd)*(1.0-clamp(col.w,0.0,1.0));
}
mat3 lookat(vec3 fw,vec3 up){
	fw=normalize(fw);vec3 rt=normalize(cross(fw,normalize(up)));return mat3(rt,cross(rt,fw),fw);
}

void mainImage( out vec4 fragColor, in vec2 fragCoord ) {
	vec3 ro=vec3(-2.25,1.5+sin(Y.x*0.9),-4);
	vec3 rd = vec3((gl_FragCoord.xy / Y.y - 0.5), 0.8);
	rd.x -= Y.z;
	L=normalize(vec3(0.5,0.5,-0.5));
	rmx=RMat2(Y.x);
	rmx1=RMat2(0.09);
	rmx2=RMat2(Y.x*10.0);

	vec3 col=Background(rd);
	float t=0.0,d=1.0;
	for(int i=0;i<64;i++){
		if(t>10.0 || d<0.005) continue;
		t+=d=DE(ro+rd*t);
	}
	if(d>=0.1 && rd.y<0.0){//fix the ground
		t=-(ro.y+1.5)/rd.y;
		d=0.0;	
	}
	if(d<0.1){//close enough for a hit
		ro+=rd*t;
		mcol=vec4(0.0);
		const vec2 v=vec2(0.001,0.0);
		vec3 N=normalize(vec3(-CE(ro-v.xyy)+CE(ro+v.xyy),-CE(ro-v.yxy)+CE(ro+v.yxy),-CE(ro-v.yyx)+CE(ro+v.yyx)));
		mcol*=0.1666;
		float refl=mcol.w;
		vec3 scol=mcol.rgb*max(0.1,0.25+dot(N,L)*0.75);
		float shadowConeGrad = 0.15;
		scol*=FuzzyShadow(ro,L,shadowConeGrad,fragCoord);//the cone grad could be calculated for each lights position
		float reflectionConeGrad = 0.09;
		scol+=refl*FuzzyReflection(ro,reflect(rd,N),reflectionConeGrad,fragCoord);//each material could have a separate cone
		col=mix(scol,col,clamp(t*0.05,0.0,1.0));
	}
	col*=1.25;
	fragColor = vec4(clamp(col,0.0,1.0),1.0);
}