struct CompositeLitSplat
{
	// Output fragment colour
	float4 color : COLOR;

};

/********************************************
*											*
*	Hi-Res Splatting Over 2 Texture Units	*
*	-------------------------------------	*
*											*
*	Performs splatting using 2 textures		*
*	over 1 texure unit. A 2nd texture unit	*
*	is used to add hi-res detail when the	*
*	tile distance is close enough to		*
*	warrant it (calculated from cam and v	*
*	pos dist). The hi-res texture contains	*
*	2 textures, one in the red channel and	*
*	one in the green.						*
*											*
*	Also calculates a simple per-vertex		*
*	ambient + diffuse lighting based on the *
*	supplied light position (x,y).			*
*											*
********************************************/


CompositeLitSplat main(float4			 inColour		: COLOR0,
					   float2			 texCoord		: TEXCOORD0,	// Tex stage 1 coordinates (used for both textures)
					   float2			 lightPos		: TEXCOORD1,	// Tex stage 2 coordinates (light pos x,y)
					   float			 blendAmount	: TEXCOORD2,	// Tex stage 3 coordinates (detail interpolationn amount)
					   uniform sampler2D splatTextures	: TEX0,			// Tex stage 1 lo-res base + detail (dirt + grass),
					   uniform sampler2D hiresTexture   : TEX1,			// Tex stage 2 hi-res detail (green = grass, red = dirt)
					   uniform float3	 vPos			: POSITION,		// Vertex position
					   uniform float1	 Ambient,						// Ambient lighting level			
					   uniform bool		 Lighting,						// Toggle lighting on/off
					   uniform float3 	 CamPos)						// Camera position (used to determine whether to use hi res or not)
{
	CompositeLitSplat OUT;

	// We need to the dirt and grass tex coords from the base coords as they are on the same texture
	float2 dirtCoord, grassCoord;

	// Used to hold grass + hi res result
	float4 grass, dirt;

	// Amount of hi-res detail texture blended onto grass texture
	const float hiresAmount = 0.07;

	OUT.color = inColour;

	// Dirt (1st half)
	dirtCoord.x = texCoord.x * 0.5;
	dirtCoord.y = texCoord.y;

	// Grass (2nd half)
	grassCoord.x = (texCoord.x * 0.5) + 0.5;
	grassCoord.y = texCoord.y;
	
	// Are we close enough to use the hi-res texture?
	if(distance(CamPos, vPos) < 25)
	{
		// Yes. Add the high-detail texture in the 2nd texture unit to the base texture from the appropriate colour channel
		grass = ((1 - hiresAmount) * tex2D(splatTextures, grassCoord)) + (hiresAmount * tex2D(hiresTexture, texCoord).g);
		dirt = ((1 - hiresAmount) * tex2D(splatTextures, dirtCoord)) + (hiresAmount * tex2D(hiresTexture, texCoord).r);
	}
	else
	{
		// No. Only use the lo res textures
		grass = tex2D(splatTextures, grassCoord);
		dirt = tex2D(splatTextures, dirtCoord);
	}

	// Lighting calculation result
	float d;

	// We using lighting?
	if(Lighting == false)
	{
		// No, setting d to 1 will result in straight up texture splatting
		d = 1.0;
	}
	else
	{  
		// Calculate the simple diffuse lighting equation
		d = clamp(1.0 - pow(dot(lightPos, lightPos), 0.5), 0.0, 1.0) + Ambient;
	}

	// Do an additive blend of the base and detail (blend 0 = 100% base, blend 1 = 100% grass, blend 0.5 = 50/50)
	OUT.color *= ((1 - blendAmount) * grass) + (blendAmount * dirt);

	
	// Now modulate the splat by the lighting result
	OUT.color *= d;

	return OUT;
}

void main(in float4  vertPosition			: POSITION,			// Vertex position		  in float4  vertColour				: COLOR0,			// Vertex colour		  in float2  texCoord				: TEXCOORD0,		// Tex stage 1 coordinates (used for both textures)		  in float2	 lightPos				: TEXCOORD1,		// Tex stage 2 coordinates (light pos x,y)		  in float	 blendAmount			: TEXCOORD2,		// Tex stage 3 coordinates (detail interpolationn amount)		  out float4 oPosition				: POSITION,			// Translated and projected vertex position          out float3 oFragPosition			: TEXCOORD3,		// Translated, projected and interpolated vertex position per fragment		  out float4 oColour				: COLOR,				  out float2 oTexCoord				: TEXCOORD0,			  out float2 oLightPos				: TEXCOORD1,			  out float	 oBlendAmount			: TEXCOORD2,			  uniform float4x4 ModelViewProj	: state.matrix.mvp)	// ModelViewPorojection matrix{	// Translate and project the vertex	oPosition =  mul(ModelViewProj, vertPosition);	// Now copy the supplied arguements over for use in the fragment shader	oFragPosition = oPosition;	oColour		  = vertColour;	oTexCoord	  = texCoord;	oLightPos	  = lightPos;	oBlendAmount  = blendAmount;}

void main(in float4			   fragColour		: COLOR0,		// Fragment colour (interpolated from vertex colour)		  in float2			   texCoord			: TEXCOORD0,	// Tex stage 1 coordinates (used for both textures)		  in float			   blendAmount		: TEXCOORD2,	// Tex stage 3 coordinates (detail interpolationn amount)		  in float3			   fragPos			: TEXCOORD3,	// Frag position interpolated from vertex position		  in uniform sampler2D splatTextures	: TEX0,			// Tex stage 1 lo-res base + detail (dirt + grass),		  in uniform sampler2D hiresTexture		: TEX1,			// Tex stage 2 hi-res detail (green = grass, red = dirt)		  in uniform bool	   useHiRes,		  out float4		   oColour			: COLOR){	// Cam is at origin as vert/frag pos is in projected world space	float3 CamPos = float3(0.0,0.0,0.0);	// Cut-off distance for the high res detail texture	float maxDist = 15.0;	// Calculate the frag's distance from the viewer	float fragDist = distance(CamPos, fragPos);	// We need to the dirt and grass tex coords from the base coords as they are on the same texture	float2 dirtCoord, grassCoord;	// Used to hold grass + hi res result	float4 grass, dirt;	// Grab the colour from the vertex stage (can be used to modulate the texture colour)	oColour = fragColour;	// Dirt (1st half)	dirtCoord.x = texCoord.x * 0.5;	dirtCoord.y = texCoord.y;	// Grass (2nd half)	grassCoord.x = (texCoord.x * 0.5) + 0.5;	grassCoord.y = texCoord.y;		// Are we close enough to use the hi-res texture?	if((useHiRes == true) && (fragDist < maxDist))	{		// Amount of hi-res detail texture blended onto grass texture		float hiresAmount;		// Max distance = 15. Therefore, any frags within 0 to 15 units is hi-res. However, in order to stop the		// hi-res texture "popping" into place, we will blend the hi res amount over the last 2 thirds of the distance		// range. The further away the frag, the less hi res detail blended in. This gives us a smooth transition		// as we zoom in and out, making the hi-res "popping" non-existent		if(fragDist > 5.0)		{			hiresAmount = 0.07 * (((maxDist - fragDist) / maxDist) + 0.5);		}		else		{			hiresAmount = 0.07;		}		// Yes. Add the high-detail texture in the 2nd texture unit to the base texture from the appropriate colour channel		grass = ((1 - hiresAmount) * tex2D(splatTextures, grassCoord)) + (hiresAmount * tex2D(hiresTexture, texCoord).g);		dirt = ((1 - hiresAmount) * tex2D(splatTextures, dirtCoord)) + (hiresAmount * tex2D(hiresTexture, texCoord).r);	}	else	{		// No. Only use the lo res textures		grass = tex2D(splatTextures, grassCoord);		dirt = tex2D(splatTextures, dirtCoord);	}	// Do an additive blend of the base and detail (blend 0 = 100% base, blend 1 = 100% grass, blend 0.5 = 50/50)	oColour *= ((1 - blendAmount) * grass) + (blendAmount * dirt);}