#version 130
//#extension GL_EXT_gpu_shader4 : enable

uniform vec3 ambient;

uniform sampler2D t0, t1, t2, tb;
uniform int gid, lightsCount;
uniform bool firstPass;
uniform vec2 dt;
uniform vec4 back_color;
uniform mat4 mat;

float light_diffuse(int model, vec3 l, vec3 n) {return max(0., dot(l, n));}
float light_specular(int model, vec3 l, vec3 n, vec3 h, vec3 v, float shininess) {return max(0., pow(dot(n, h), shininess));}

vec4 pos, lpos;
vec3 li, si, ldir, halfV;
float sh_pow, sh_mul, dist, NdotL, spot, ldist, diff;

void calcLight(in int index, in vec3 n, in vec3 v, in vec4 v2) {
	lpos = gl_LightSource[index].position;
	ldir = lpos.xyz - (pos.xyz * lpos.w);
	ldist = length(ldir);
	ldir = normalize(ldir);
	NdotL = max(dot(n, ldir), 0.);
	spot = step(0., NdotL);
	if (NdotL > 0.) {
		if (gl_LightSource[index].spotCutoff < 180.) {
			spot = max(dot(-ldir, gl_LightSource[index].spotDirection.xyz), 0.);
			spot *= step(gl_LightSource[index].spotCosCutoff, spot);
			spot = pow(spot, (gl_LightSource[index].spotExponent + 0.001));
		}
		halfV = normalize(ldir + v);
		spot /= (gl_LightSource[index].constantAttenuation + ldist * (gl_LightSource[index].linearAttenuation + ldist * gl_LightSource[index].quadraticAttenuation));
		//li += spot * gl_LightSource[index].diffuse.rgb * light_diffuse(0, ldir, n);
		//si += spot * gl_LightSource[index].specular.rgb * sh_mul * light_specular(0, ldir, n, halfV, v, sh_pow);
		float NdotLs = NdotL*NdotL;
		float ndlc = (1. - NdotLs) / NdotLs;
		float der = NdotLs * (sh_mul + ndlc);
		diff = 2. / (1. + sqrt(1. + (1. - sh_mul) * ndlc));
		li += spot * gl_LightSource[index].diffuse.rgb * diff * light_diffuse(0, ldir, n);
		si += spot * gl_LightSource[index].specular.rgb * (sh_mul / (der*der) / 3.1416);
	}
}

void main(void) {
	//if (d == 1.) discard;
	vec4 v0 = texture2D(t0, gl_TexCoord[0].xy);
	if (v0.w == 0.) {
		gl_FragColor = back_color;
		return;
	}
	vec4 v1 = texture2D(t1, gl_TexCoord[0].xy), v2 = texture2D(t2, gl_TexCoord[0].xy);//, v3 = texture2D(t2, gl_TexCoord[0].xy);
	vec2 sp = gl_FragCoord.xy * dt * 2 - vec2(1, 1);
	vec3 dc = v0.rgb, n = v1.xyz * 2. - vec3(1.);
	float height = v2.w;
	li = gl_LightModel.ambient.rgb;
	si = vec3(0.);

	pos = vec4(sp, 0, 1.) * mat;
	pos *= v0.w;
	pos.rgb += n * height;
	vec3 v = normalize(-pos.xyz);
	sh_pow = 1. / max((1. - v1.w), 0.0001);
	sh_mul = max(1. - v1.w, 0.0001);
	if (lightsCount > 0) {
		calcLight(0, n, v, v2);
		if (lightsCount > 1) {
			calcLight(1, n, v, v2);
			if (lightsCount > 2) {
				calcLight(2, n, v, v2);
				if (lightsCount > 3) {
					calcLight(3, n, v, v2);
					if (lightsCount > 4) {
						calcLight(4, n, v, v2);
						if (lightsCount > 5) {
							calcLight(5, n, v, v2);
							if (lightsCount > 6) {
								calcLight(6, n, v, v2);
								if (lightsCount > 7) {
									calcLight(7, n, v, v2);
								}
							}
						}
					}
				}
			}
		}
	}
	gl_FragColor.rgb = li * dc + si * v2.rgb + texture2D(tb, gl_TexCoord[0].xy).rgb;
	//gl_FragColor.rgb = vec3(v2.rgb);
}