#version 150
//#extension GL_EXT_gpu_shader4 : enable

in vec4 view_dir, view_pos;

uniform vec3 ambient;
uniform sampler2D t0, t1, t2, t3, t4, t_pp;
uniform sampler2D td;
uniform int gid, lightsCount;
uniform float z_near, z_far;
uniform bool firstPass;
uniform vec2 dt;
uniform vec4 back_color;
uniform mat4 mat_proji;

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, NdotH, spot, ldist, diff;

void calcLight(in int index, in vec3 n, in vec3 v, in vec4 v2) {
	lpos = qgl_Light[index].position;
	ldir = lpos.xyz - (pos.xyz * lpos.w);
	ldist = length(ldir);
	ldir = normalize(ldir);
	halfV = normalize(ldir + v);
	NdotL = max(dot(n, ldir), 0.);
	NdotH = max(dot(n, halfV), 0.);
	spot = step(0., NdotL) * qgl_Light[index].intensity;
	if (NdotL > 0.) {
		if (qgl_Light[index].endAngle <= 90.) {
			float scos = max(dot(-ldir, qgl_Light[index].direction.xyz), 0.);
			spot *= scos * step(qgl_Light[index].endAngleCos, scos);
			//spot = clamp(scos / (-qgl_Light[index].endAngleCos + qgl_Light[index].startAngleCos + 0.0001),0,1);
			spot *= smoothstep(qgl_Light[index].endAngleCos, qgl_Light[index].startAngleCos, scos);
			//spot = pow(spot, (qgl_Light[index].spotExponent + 0.001));
		}
		spot /= (qgl_Light[index].constantAttenuation + ldist * (qgl_Light[index].linearAttenuation + ldist * qgl_Light[index].quadraticAttenuation));
		///li += spot * gl_LightSource[index].diffuse.rgb * light_diffuse(0, ldir, n);
		//si += spot * qgl_Light[index].color.rgb * sh_mul * light_specular(0, ldir, n, halfV, v, sh_pow);
		float NdotLs = NdotL*NdotL;
		float NdotHs = NdotH*NdotH;
		float ndlc = (1. - NdotLs) / NdotLs;
		float der = NdotLs * (sh_mul + ndlc);
		diff = 2. / (1. + sqrt(1. + (1. - sh_mul) * ndlc));
		li += spot * qgl_Light[index].color.rgb * diff;// * light_diffuse(0, ldir, n);
		ndlc = (1. - NdotHs) / NdotHs;
		der = NdotHs * (sh_mul + ndlc);
		si += spot * qgl_Light[index].color.rgb * (sh_mul / (der*der) / 3.1416);
		//si += der;//dot(n, halfV);
	}
}

void main(void) {
	//if (d == 1.) discard;
	ivec2 tc = ivec2(gl_FragCoord.xy);
	vec4 v0 = texture2D(t0, qgl_FragTexture.xy);
	if (v0.w == 0.) {
		qgl_FragData[0] = back_color;
		return;
	}
	vec4 v1 = texelFetch(t1, tc, 0),
		 v2 = texelFetch(t2, tc, 0),
		 v3 = texelFetch(t3, tc, 0),
		 v4 = texelFetch(t4, tc, 0);
	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 = qgl_AmbientLight.color.rgb * qgl_AmbientLight.intensity;
	//li = vec3(0.);
	si = vec3(0.);

	float posz = z_near * z_far / (texture2D(td, tc).r * (z_far - z_near) - z_far);
	pos = vec4(sp, 0., 1) * mat_proji;
	pos.xy *= v3.w;
	pos.z = posz;
	pos.xyz += n * height;
	//pos.xyz = v3.xyz;
	//pos = v3;
	//pos = vec4(sp, 0, 1.) * mat_proji;
	//pos *= v0.w;
	//pos.z += 1;
	//pos.xy *= 10.;
	//pos.z = v0.w;
	vec3 v = normalize(-pos.xyz);

	sh_pow = 1. / max((1. - v1.w), 0.0001);
	sh_mul = max(1. - v1.w, 0.0001);
	for (int i = 0; i < 16; ++i)
		calcLight(i, n, v, v2);

	qgl_FragData[0].rgb = li * dc + si * v2.rgb + v3.rgb + texture(t_pp, tc).rgb;
	//qgl_FragData[0].rgb = vec3(abs(lpos.xyz - pos.xyz)/10);
	//qgl_FragData[0].rgb = si.rgb;
	//qgl_FragData[0].rgb = vec3(length(v4.xyz)/10);
	//qgl_FragData[0].a = 0.;
}