#include "$ENGINE$\GBuffer.bslinc"
#include "$ENGINE$\PerCameraData.bslinc"

Parameters =
{
	Sampler2D 	gGBufferASamp : alias("gGBufferATex");
	Sampler2D 	gGBufferBSamp : alias("gGBufferBTex");
	Sampler2D 	gDepthBufferSamp : alias("gDepthBufferTex");
	
	Texture2D 	gGBufferATex : auto("GBufferA");
	Texture2D	gGBufferBTex : auto("GBufferB");
	Texture2D 	gDepthBufferTex : auto("GBufferDepth");
};

Blocks =
{
	Block PerCamera : auto("PerCamera");
	Block PerLight : auto("PerLight");
};

Technique
 : base("DeferredLightPass")
 : inherits("GBuffer")
 : inherits("PerCameraData") =
{
	Language = "HLSL11";
	
	Pass =
	{
		Target = 
		{
			Blend = true;
			Color = { ONE, ONE, ADD };
			WriteMask = RGB;
		};
		
		DepthWrite = false;

		Common = 
		{
			#define PI 3.1415926
			#define HALF_PI 1.5707963
			
			cbuffer PerLight
			{
				// x, y, z - World position of the lightData
				// w - Type type - Directional = 0, Point = >0, Spot = >0.5
				float4 gLightPositionAndType;
				float4 gLightColorAndIntensity;
				// x - outerAngle in radians, y - cos(outerAngle), z - 1.0f/(cos(innerAngle) - cos(outerAngle)), w - inverse point light radius
				float4 gLightSpotAnglesAndSqrdInvRadius;
				float3 gLightDirection;
				
				// x - Num sides (zero for point lights)
				// y - Num slices (zero for point lights)
				// z - Sphere radius for point lights
				// w - Cone radius for spot lights
				float4 gLightGeometry; 
				float4x4 gMatConeTransform;
			}
			
			struct LightData
			{
				float3 position;
				float3 direction;
				float intensity;
				bool isSpot;
				bool isPoint;
				float3 spotAngles; 
				float3 color;
				float radiusSqrdInv;
			};
			
			float convertFromDeviceZ(float deviceZ)
			{
				return (1.0f / (deviceZ + gDeviceZToWorldZ.y)) * gDeviceZToWorldZ.x;
			}
			
			GBufferData decodeGBuffer(float4 GBufferAData, float4 GBufferBData, float deviceZ)
			{
				GBufferData output;
				
				output.albedo.xyz = GBufferAData.xyz;
				output.albedo.w = 1.0f;
				output.worldNormal = GBufferBData * float4(2, 2, 2, 1) - float4(1, 1, 1, 0);
				output.worldNormal.xyz = normalize(output.worldNormal.xyz);
				output.depth = convertFromDeviceZ(deviceZ);
				
				return output;
			}
			
			LightData getLightData()
			{
				LightData output;
				
				output.position = gLightPositionAndType.xyz;
				output.direction = gLightDirection;
				output.color = gLightColorAndIntensity.rgb;
				output.intensity = gLightColorAndIntensity.w;
				output.isPoint = gLightPositionAndType.w > 0.0f;
				output.isSpot = gLightPositionAndType.w > 0.5f;
				output.spotAngles = gLightSpotAnglesAndSqrdInvRadius.xyz;
				output.radiusSqrdInv = gLightSpotAnglesAndSqrdInvRadius.w;
				
				return output;
			}
			
			float getSpotAttenuation(float3 worldPosToLight, float3 direction, float3 angles)
			{
				float output = saturate((dot(-worldPosToLight, direction) - angles.y) * angles.z);
				return output * output;
			}			
			
			float4 getLighting(float3 worldPosition, float2 uv, GBufferData gBuffer, LightData lightData)
			{
				float3 N = gBuffer.worldNormal.xyz;
				float NoL = 1.0f;
				
				float distanceAttenuation = 1.0f;
				float spotFalloff = 1.0f;
				float radiusAttenuation = 1.0f;
				if (lightData.isPoint)
				{
					float3 L = lightData.position - worldPosition;
					
					float distanceSqrd = dot(L, L);
					distanceAttenuation = 1/(distanceSqrd + 1);
					
					L = normalize(L);
					NoL = saturate(dot(N, L)); // TODO - Add bias here?

					radiusAttenuation = distanceSqrd * lightData.radiusSqrdInv;
					radiusAttenuation *= radiusAttenuation;
					radiusAttenuation = saturate(1.0f - radiusAttenuation);
					radiusAttenuation *= radiusAttenuation;
					
					if (lightData.isSpot)
						spotFalloff = getSpotAttenuation(L, lightData.direction, lightData.spotAngles);
				}
				else
				{
					float3 L = -lightData.direction;
					NoL = saturate(dot(N, L)); // TODO - Add bias here?
				}

				float attenuation = distanceAttenuation * spotFalloff * radiusAttenuation;

				float3 diffuse = gBuffer.albedo.xyz / PI; // TODO - Add better lighting model later

				float4 output = float4(lightData.color * lightData.intensity * ((NoL * attenuation) * diffuse), 1);
				return output;
			}
		};
		
		Fragment = 
		{
			SamplerState 	gGBufferASamp : register(s0);
			SamplerState 	gGBufferBSamp : register(s1);
			SamplerState 	gDepthBufferSamp : register(s2);
	
			Texture2D 	gGBufferATex : register(t0);
			Texture2D	gGBufferBTex : register(t1);
			Texture2D 	gDepthBufferTex : register(t2);
			
			GBufferData getGBufferData(float2 uv)
			{
				float4 GBufferAData = gGBufferATex.SampleLevel(gGBufferASamp, uv, 0);
				float4 GBufferBData = gGBufferBTex.SampleLevel(gGBufferBSamp, uv, 0);
				float deviceZ = gDepthBufferTex.SampleLevel(gDepthBufferSamp, uv, 0).r;
				
				return decodeGBuffer(GBufferAData, GBufferBData, deviceZ);
			}			
		};	
	};
};

Technique
 : base("DeferredLightPass")
 : inherits("GBuffer")
 : inherits("PerCameraData") =
{
	Language = "GLSL";
	
	Pass =
	{
		Target = 
		{
			Blend = true;
			Color = { ONE, ONE, ADD };
			WriteMask = RGB;
		};
		
		DepthWrite = false;

		Common = 
		{
			#define PI 3.1415926
			#define HALF_PI 1.5707963
			
			layout(std140) uniform PerLight
			{
				// x, y, z - World position of the lightData
				// w - Type type - Directional = 0, Point = >0, Spot = >0.5
				vec4 gLightPositionAndType;
				vec4 gLightColorAndIntensity;
				// x - outerAngle in radians, y - cos(outerAngle), z - 1.0f/(cos(innerAngle) - cos(outerAngle)), w - inverse point light radius
				vec4 gLightSpotAnglesAndSqrdInvRadius;
				vec3 gLightDirection;
				
				// x - Num sides (zero for point lights)
				// y - Num slices (zero for point lights)
				// z - Sphere radius for point lights
				// w - Cone radius for spot lights
				vec4 gLightGeometry; 
				mat4 gMatConeTransform;
			};
			
			struct LightData
			{
				vec3 position;
				vec3 direction;
				float intensity;
				bool isSpot;
				bool isPoint;
				vec3 spotAngles; 
				vec3 color;
				float radiusSqrdInv;
			};
			
			float convertFromDeviceZ(float deviceZ)
			{
				return (1.0f / (deviceZ + gDeviceZToWorldZ.y)) * gDeviceZToWorldZ.x;	
			}
			
			GBufferData decodeGBuffer(vec4 GBufferAData, vec4 GBufferBData, float deviceZ)
			{
				GBufferData gBufferData;
				
				gBufferData.albedo.xyz = GBufferAData.xyz;
				gBufferData.albedo.w = 1.0f;
				gBufferData.worldNormal = GBufferBData * vec4(2, 2, 2, 1) - vec4(1, 1, 1, 0);
				gBufferData.worldNormal.xyz = normalize(gBufferData.worldNormal.xyz);
				gBufferData.depth = convertFromDeviceZ(deviceZ);
				
				return gBufferData;
			}
			
			LightData getLightData()
			{
				LightData lightData;
				
				lightData.position = gLightPositionAndType.xyz;
				lightData.direction = gLightDirection;
				lightData.color = gLightColorAndIntensity.rgb;
				lightData.intensity = gLightColorAndIntensity.w;
				lightData.isPoint = gLightPositionAndType.w > 0.0f;
				lightData.isSpot = gLightPositionAndType.w > 0.5f;
				lightData.spotAngles = gLightSpotAnglesAndSqrdInvRadius.xyz;
				lightData.radiusSqrdInv = gLightSpotAnglesAndSqrdInvRadius.w;
				
				return lightData;
			}
			
			float getSpotAttenuation(vec3 worldPosToLight, vec3 direction, vec3 angles)
			{
				float atten = clamp((dot(-worldPosToLight, direction) - angles.y) * angles.z, 0.0, 1.0);
				return atten * atten;
			}			
			
			vec4 getLighting(vec3 worldPosition, vec2 uv, GBufferData gBuffer, LightData lightData)
			{
				vec3 N = gBuffer.worldNormal.xyz;
				float NoL = 1.0f;
				
				float distanceAttenuation = 1.0f;
				float spotFalloff = 1.0f;
				float radiusAttenuation = 1.0f;
				if (lightData.isPoint)
				{
					vec3 L = lightData.position - worldPosition;
					
					float distanceSqrd = dot(L, L);
					distanceAttenuation = 1/(distanceSqrd + 1);
					
					L = normalize(L);
					NoL = clamp(dot(N, L), 0.0, 1.0); // TODO - Add bias here?

					radiusAttenuation = distanceSqrd * lightData.radiusSqrdInv;
					radiusAttenuation *= radiusAttenuation;
					radiusAttenuation = clamp(1.0f - radiusAttenuation, 0.0, 1.0);
					radiusAttenuation *= radiusAttenuation;
					
					if (lightData.isSpot)
						spotFalloff = getSpotAttenuation(L, lightData.direction, lightData.spotAngles);
				}
				else
				{
					vec3 L = -lightData.direction;
					NoL = clamp(dot(N, L), 0.0, 1.0); // TODO - Add bias here?
				}

				float attenuation = distanceAttenuation * spotFalloff * radiusAttenuation;

				vec3 diffuse = gBuffer.albedo.xyz / PI; // TODO - Add better lighting model later

				vec4 lighting = vec4(lightData.color * lightData.intensity * ((NoL * attenuation) * diffuse), 1);
				return lighting;
			}
		};
		
		Fragment = 
		{
			uniform sampler2D gGBufferATex;
			uniform sampler2D gGBufferBTex;
			uniform sampler2D gDepthBufferTex;
			
			GBufferData getGBufferData(vec2 uv)
			{
				vec4 GBufferAData = textureLod(gGBufferATex, uv, 0);
				vec4 GBufferBData = textureLod(gGBufferBTex, uv, 0);
				float deviceZ = textureLod(gDepthBufferTex, uv, 0).r;
				
				return decodeGBuffer(GBufferAData, GBufferBData, deviceZ);
			}			
		};	
	};
};