#ifdef GL_ES
precision highp float;
#endif

#define MAP_PROJECTION	4.

// Constants
uniform vec3 vEyePosition;
uniform vec3 vAmbientColor;
uniform vec4 vDiffuseColor;
uniform vec4 vSpecularColor;
uniform vec3 vEmissiveColor;

// Input
varying vec3 vPositionW;
varying vec3 vNormalW;

#ifdef VERTEXCOLOR
varying vec3 vColor;
#endif

// Lights
#ifdef LIGHT0
uniform vec4 vLightData0;
uniform vec4 vLightDiffuse0;
uniform vec3 vLightSpecular0;
#ifdef SHADOW0
varying vec4 vPositionFromLight0;
uniform sampler2D shadowSampler0;
#endif
#ifdef SPOTLIGHT0
uniform vec4 vLightDirection0;
#endif
#ifdef HEMILIGHT0
uniform vec3 vLightGround0;
#endif
#endif

#ifdef LIGHT1
uniform vec4 vLightData1;
uniform vec4 vLightDiffuse1;
uniform vec3 vLightSpecular1;
#ifdef SHADOW1
varying vec4 vPositionFromLight1;
uniform sampler2D shadowSampler1;
#endif
#ifdef SPOTLIGHT1
uniform vec4 vLightDirection1;
#endif
#ifdef HEMILIGHT1
uniform vec3 vLightGround1;
#endif
#endif

#ifdef LIGHT2
uniform vec4 vLightData2;
uniform vec4 vLightDiffuse2;
uniform vec3 vLightSpecular2;
#ifdef SHADOW2
varying vec4 vPositionFromLight2;
uniform sampler2D shadowSampler2;
#endif
#ifdef SPOTLIGHT2
uniform vec4 vLightDirection2;
#endif
#ifdef HEMILIGHT2
uniform vec3 vLightGround2;
#endif
#endif

#ifdef LIGHT3
uniform vec4 vLightData3;
uniform vec4 vLightDiffuse3;
uniform vec3 vLightSpecular3;
#ifdef SHADOW3
varying vec4 vPositionFromLight3;
uniform sampler2D shadowSampler3;
#endif
#ifdef SPOTLIGHT3
uniform vec4 vLightDirection3;
#endif
#ifdef HEMILIGHT3
uniform vec3 vLightGround3;
#endif
#endif

// Samplers
#ifdef DIFFUSE
varying vec2 vDiffuseUV;
uniform sampler2D diffuseSampler;
uniform vec2 vDiffuseInfos;
#endif

#ifdef AMBIENT
varying vec2 vAmbientUV;
uniform sampler2D ambientSampler;
uniform vec2 vAmbientInfos;
#endif

#ifdef OPACITY	
varying vec2 vOpacityUV;
uniform sampler2D opacitySampler;
uniform vec2 vOpacityInfos;
#endif

#ifdef REFLECTION
varying vec3 vReflectionUVW;
uniform samplerCube reflectionCubeSampler;
uniform sampler2D reflection2DSampler;
uniform vec3 vReflectionInfos;
#endif

#ifdef EMISSIVE
varying vec2 vEmissiveUV;
uniform vec2 vEmissiveInfos;
uniform sampler2D emissiveSampler;
#endif

#ifdef SPECULAR
varying vec2 vSpecularUV;
uniform vec2 vSpecularInfos;
uniform sampler2D specularSampler;
#endif

// Fresnel
#ifdef FRESNEL
float computeFresnelTerm(vec3 viewDirection, vec3 worldNormal, float bias, float power)
{
	float fresnelTerm = pow(bias + abs(dot(viewDirection, worldNormal)), power);
	return clamp(fresnelTerm, 0., 1.);
}
#endif

#ifdef DIFFUSEFRESNEL
uniform vec4 diffuseLeftColor;
uniform vec4 diffuseRightColor;
#endif

#ifdef OPACITYFRESNEL
uniform vec4 opacityParts;
#endif

#ifdef REFLECTIONFRESNEL
uniform vec4 reflectionLeftColor;
uniform vec4 reflectionRightColor;
#endif

#ifdef EMISSIVEFRESNEL
uniform vec4 emissiveLeftColor;
uniform vec4 emissiveRightColor;
#endif

// Shadows
#ifdef SHADOWS

float unpack(vec4 color)
{
	const vec4 bitShift = vec4(1. / (255. * 255. * 255.), 1. / (255. * 255.), 1. / 255., 1.);
	return dot(color, bitShift);
}

float unpackHalf(vec2 color)
{
	return color.x + (color.y / 255.0);
}

float computeShadow(vec4 vPositionFromLight, sampler2D shadowSampler)
{
	vec3 depth = vPositionFromLight.xyz / vPositionFromLight.w;
	vec2 uv = 0.5 * depth.xy + vec2(0.5, 0.5);

	if (uv.x < 0. || uv.x > 1.0 || uv.y < 0. || uv.y > 1.0)
	{
		return 1.0;
	}

	float shadow = unpack(texture2D(shadowSampler, uv));

	if (depth.z > shadow)
	{
		return 0.;
	}
	return 1.;
}

// Thanks to http://devmaster.net/
float ChebychevInequality(vec2 moments, float t)
{
	if (t <= moments.x)
	{
		return 1.0;
	}

	float variance = moments.y - (moments.x * moments.x);
	variance = max(variance, 0.);

	float d = t - moments.x;
	return variance / (variance + d * d);
}

float computeShadowWithVSM(vec4 vPositionFromLight, sampler2D shadowSampler)
{
	vec3 depth = vPositionFromLight.xyz / vPositionFromLight.w;
	vec2 uv = 0.5 * depth.xy + vec2(0.5, 0.5);

	if (uv.x < 0. || uv.x > 1.0 || uv.y < 0. || uv.y > 1.0)
	{
		return 1.0;
	}

	vec4 texel = texture2D(shadowSampler, uv);

	vec2 moments = vec2(unpackHalf(texel.xy), unpackHalf(texel.zw));
	return clamp(1.3 - ChebychevInequality(moments, depth.z), 0., 1.0);
}
#endif

#ifdef CLIPPLANE
varying float fClipDistance;
#endif

// Fog
#ifdef FOG

#define FOGMODE_NONE    0.
#define FOGMODE_EXP     1.
#define FOGMODE_EXP2    2.
#define FOGMODE_LINEAR  3.
#define E 2.71828

uniform vec4 vFogInfos;
uniform vec3 vFogColor;
varying float fFogDistance;

float CalcFogFactor()
{
	float fogCoeff = 1.0;
	float fogStart = vFogInfos.y;
	float fogEnd = vFogInfos.z;
	float fogDensity = vFogInfos.w;

	if (FOGMODE_LINEAR == vFogInfos.x)
	{
		fogCoeff = (fogEnd - fFogDistance) / (fogEnd - fogStart);
	}
	else if (FOGMODE_EXP == vFogInfos.x)
	{
		fogCoeff = 1.0 / pow(E, fFogDistance * fogDensity);
	}
	else if (FOGMODE_EXP2 == vFogInfos.x)
	{
		fogCoeff = 1.0 / pow(E, fFogDistance * fFogDistance * fogDensity * fogDensity);
	}

	return clamp(fogCoeff, 0.0, 1.0);
}
#endif

// Light Computing
mat3 computeLighting(vec3 viewDirectionW, vec3 vNormal, vec4 lightData, vec4 diffuseColor, vec3 specularColor) {
	mat3 result;

	vec3 lightVectorW;
	if (lightData.w == 0.)
	{
		lightVectorW = normalize(lightData.xyz - vPositionW);
	}
	else
	{
		lightVectorW = normalize(-lightData.xyz);
	}

	// diffuse
	float ndl = max(0., dot(vNormal, lightVectorW));

	// Specular
	vec3 angleW = normalize(viewDirectionW + lightVectorW);
	float specComp = max(0., dot(vNormal, angleW));
	specComp = max(0., pow(specComp, max(1.0, vSpecularColor.a)));

	result[0] = ndl * diffuseColor.rgb;
	result[1] = specComp * specularColor;
	result[2] = vec3(0.);

	return result;
}

mat3 computeSpotLighting(vec3 viewDirectionW, vec3 vNormal, vec4 lightData, vec4 lightDirection, vec4 diffuseColor, vec3 specularColor) {
	mat3 result;

	vec3 lightVectorW = normalize(lightData.xyz - vPositionW);

	// diffuse
	float cosAngle = max(0., dot(-lightDirection.xyz, lightVectorW));
	float spotAtten = 0.0;

	if (cosAngle >= lightDirection.w)
	{
		cosAngle = max(0., pow(cosAngle, lightData.w));
		spotAtten = max(0., (cosAngle - lightDirection.w) / (1. - cosAngle));

		// Diffuse
		float ndl = max(0., dot(vNormal, -lightDirection.xyz));

		// Specular
		vec3 angleW = normalize(viewDirectionW - lightDirection.xyz);
		float specComp = max(0., dot(vNormal, angleW));
		specComp = pow(specComp, vSpecularColor.a);

		result[0] = ndl * spotAtten * diffuseColor.rgb;
		result[1] = specComp * specularColor * spotAtten;
		result[2] = vec3(0.);

		return result;
	}

	result[0] = vec3(0.);
	result[1] = vec3(0.);
	result[2] = vec3(0.);

	return result;
}

mat3 computeHemisphericLighting(vec3 viewDirectionW, vec3 vNormal, vec4 lightData, vec4 diffuseColor, vec3 specularColor, vec3 groundColor) {
	mat3 result;

	// Diffuse
	float ndl = dot(vNormal, lightData.xyz) * 0.5 + 0.5;

	// Specular
	vec3 angleW = normalize(viewDirectionW + lightData.xyz);
	float specComp = max(0., dot(vNormal, angleW));
	specComp = pow(specComp, vSpecularColor.a);

	result[0] = mix(groundColor, diffuseColor.rgb, ndl);
	result[1] = specComp * specularColor;
	result[2] = vec3(0.);

	return result;
}

void main(void) {
	// Clip plane
#ifdef CLIPPLANE
	if (fClipDistance > 0.0)
		discard;
#endif

	vec3 viewDirectionW = normalize(vEyePosition - vPositionW);

	// Base color
	vec4 baseColor = vec4(1., 1., 1., 1.);
	vec3 diffuseColor = vDiffuseColor.rgb;

#ifdef VERTEXCOLOR
	diffuseColor *= vColor;
#endif

#ifdef DIFFUSE
	baseColor = texture2D(diffuseSampler, vDiffuseUV);

#ifdef ALPHATEST
	if (baseColor.a < 0.4)
		discard;
#endif

	baseColor.rgb *= vDiffuseInfos.y;
#endif

	// Bump
	vec3 normalW = normalize(vNormalW);

	// Ambient color
	vec3 baseAmbientColor = vec3(1., 1., 1.);

#ifdef AMBIENT
	baseAmbientColor = texture2D(ambientSampler, vAmbientUV).rgb * vAmbientInfos.y;
#endif

	// Lighting
	vec3 diffuseBase = vec3(0., 0., 0.);
	vec3 specularBase = vec3(0., 0., 0.);
	float shadow = 1.;

#ifdef LIGHT0
#ifdef SPOTLIGHT0
	mat3 info = computeSpotLighting(viewDirectionW, normalW, vLightData0, vLightDirection0, vLightDiffuse0, vLightSpecular0);
#endif
#ifdef HEMILIGHT0
	mat3 info = computeHemisphericLighting(viewDirectionW, normalW, vLightData0, vLightDiffuse0, vLightSpecular0, vLightGround0);
#endif
#ifdef POINTDIRLIGHT0
	mat3 info = computeLighting(viewDirectionW, normalW, vLightData0, vLightDiffuse0, vLightSpecular0);
#endif
#ifdef SHADOW0
#ifdef SHADOWVSM0
	shadow = computeShadowWithVSM(vPositionFromLight0, shadowSampler0);
#else
	shadow = computeShadow(vPositionFromLight0, shadowSampler0);
#endif
#else
	shadow = 1.;
#endif
	diffuseBase += info[0] * shadow;
	specularBase += info[1] * shadow;
#endif

#ifdef LIGHT1
#ifdef SPOTLIGHT1
	info = computeSpotLighting(viewDirectionW, normalW, vLightData1, vLightDirection1, vLightDiffuse1, vLightSpecular1);
#endif
#ifdef HEMILIGHT1
	info = computeHemisphericLighting(viewDirectionW, normalW, vLightData1, vLightDiffuse1, vLightSpecular1, vLightGround1);
#endif
#ifdef POINTDIRLIGHT1
	info = computeLighting(viewDirectionW, normalW, vLightData1, vLightDiffuse1, vLightSpecular1);
#endif
#ifdef SHADOW1
#ifdef SHADOWVSM1
	shadow = computeShadowWithVSM(vPositionFromLight1, shadowSampler1);
#else
	shadow = computeShadow(vPositionFromLight1, shadowSampler1);
#endif
#else
	shadow = 1.;
#endif
	diffuseBase += info[0] * shadow;
	specularBase += info[1] * shadow;
#endif

#ifdef LIGHT2
#ifdef SPOTLIGHT2
	info = computeSpotLighting(viewDirectionW, normalW, vLightData2, vLightDirection2, vLightDiffuse2, vLightSpecular2);
#endif
#ifdef HEMILIGHT2
	info = computeHemisphericLighting(viewDirectionW, normalW, vLightData2, vLightDiffuse2, vLightSpecular2, vLightGround2);
#endif
#ifdef POINTDIRLIGHT2
	info = computeLighting(viewDirectionW, normalW, vLightData2, vLightDiffuse2, vLightSpecular2);
#endif
#ifdef SHADOW2
#ifdef SHADOWVSM2
	shadow = computeShadowWithVSM(vPositionFromLight2, shadowSampler2);
#else
	shadow = computeShadow(vPositionFromLight2, shadowSampler2);
#endif	
#else
	shadow = 1.;
#endif
	diffuseBase += info[0] * shadow;
	specularBase += info[1] * shadow;
#endif

#ifdef LIGHT3
#ifdef SPOTLIGHT3
	info = computeSpotLighting(viewDirectionW, normalW, vLightData3, vLightDirection3, vLightDiffuse3, vLightSpecular3);
#endif
#ifdef HEMILIGHT3
	info = computeHemisphericLighting(viewDirectionW, normalW, vLightData3, vLightDiffuse3, vLightSpecular3, vLightGround3);
#endif
#ifdef POINTDIRLIGHT3
	info = computeLighting(viewDirectionW, normalW, vLightData3, vLightDiffuse3, vLightSpecular3);
#endif
#ifdef SHADOW3
#ifdef SHADOWVSM3
	shadow = computeShadowWithVSM(vPositionFromLight3, shadowSampler3);
#else
	shadow = computeShadow(vPositionFromLight3, shadowSampler3);
#endif	
#else
	shadow = 1.;
#endif
	diffuseBase += info[0] * shadow;
	specularBase += info[1] * shadow;
#endif

	// Reflection
	vec3 reflectionColor = vec3(0., 0., 0.);

#ifdef REFLECTION
	if (vReflectionInfos.z != 0.0)
	{
		reflectionColor = textureCube(reflectionCubeSampler, vReflectionUVW).rgb * vReflectionInfos.y;
	}
	else
	{
		vec2 coords = vReflectionUVW.xy;

		if (vReflectionInfos.x == MAP_PROJECTION)
		{
			coords /= vReflectionUVW.z;
		}

		coords.y = 1.0 - coords.y;

		reflectionColor = texture2D(reflection2DSampler, coords).rgb * vReflectionInfos.y;
	}

#ifdef REFLECTIONFRESNEL
	float reflectionFresnelTerm = computeFresnelTerm(viewDirectionW, normalW, reflectionRightColor.a, reflectionLeftColor.a);

	reflectionColor *= reflectionLeftColor.rgb * (1.0 - reflectionFresnelTerm) + reflectionFresnelTerm * reflectionRightColor.rgb;
#endif
#endif

	// Alpha
	float alpha = vDiffuseColor.a;

#ifdef OPACITY
	vec4 opacityMap = texture2D(opacitySampler, vOpacityUV);
#ifdef OPACITYRGB
	opacityMap.rgb = opacityMap.rgb * vec3(0.3, 0.59, 0.11);
	alpha *= (opacityMap.x + opacityMap.y + opacityMap.z)* vOpacityInfos.y;
#else
	alpha *= opacityMap.a * vOpacityInfos.y;
#endif
#endif

#ifdef OPACITYFRESNEL
	float opacityFresnelTerm = computeFresnelTerm(viewDirectionW, normalW, opacityParts.z, opacityParts.w);

	alpha += opacityParts.x * (1.0 - opacityFresnelTerm) + opacityFresnelTerm * opacityParts.y;
#endif

	// Emissive
	vec3 emissiveColor = vEmissiveColor;
#ifdef EMISSIVE
	emissiveColor += texture2D(emissiveSampler, vEmissiveUV).rgb * vEmissiveInfos.y;
#endif

#ifdef EMISSIVEFRESNEL
	float emissiveFresnelTerm = computeFresnelTerm(viewDirectionW, normalW, emissiveRightColor.a, emissiveLeftColor.a);

	emissiveColor *= emissiveLeftColor.rgb * (1.0 - emissiveFresnelTerm) + emissiveFresnelTerm * emissiveRightColor.rgb;
#endif

	// Specular map
	vec3 specularColor = vSpecularColor.rgb;
#ifdef SPECULAR
	specularColor = texture2D(specularSampler, vSpecularUV).rgb * vSpecularInfos.y;
#endif

	// Fresnel
#ifdef DIFFUSEFRESNEL
	float diffuseFresnelTerm = computeFresnelTerm(viewDirectionW, normalW, diffuseRightColor.a, diffuseLeftColor.a);

	diffuseBase *= diffuseLeftColor.rgb * (1.0 - diffuseFresnelTerm) + diffuseFresnelTerm * diffuseRightColor.rgb;
#endif

	// Composition
	vec3 finalDiffuse = clamp(diffuseBase * diffuseColor + emissiveColor + vAmbientColor, 0.0, 1.0) * baseColor.rgb;
	vec3 finalSpecular = specularBase * specularColor;

	vec4 color = vec4(finalDiffuse * baseAmbientColor + finalSpecular + reflectionColor, alpha);

#ifdef FOG
	float fog = CalcFogFactor();
	color.rgb = fog * color.rgb + (1.0 - fog) * vFogColor;
#endif

	gl_FragColor = color;
}