//Application fed data
const float4x4 matWorldViewProj;
const float4x4 matWorld;

texture Sand_BM_bmap, Grass_BM_bmap, Rock_BM_bmap, Snow_BM_bmap;

// ColorMap Samplers
sampler SandSampler  = sampler_state  { Texture = <Sand_BM_bmap>;  };
sampler GrassSampler = sampler_state  { Texture = <Grass_BM_bmap>; };
sampler RockSampler  = sampler_state  { Texture = <Rock_BM_bmap>;  };
sampler SnowSampler  = sampler_state  { Texture = <Snow_BM_bmap>;  };


// Vertex Shader: 
void TerrPaintVS( in  float4 InPos:  POSITION,	in  float2 InTex: TEXCOORD0, 
						out float4 OutPos: POSITION,	out float2 OutTex: TEXCOORD0, 
						out float  Height: TEXCOORD1 											)	 
{ 
	// Temporarily transform the vertex from object space to world space: 
	OutPos = mul(InPos, 	matWorld);
	// Capture the HEIGHT data of the vertices
	Height = 1-(OutPos.y/OutPos.w);
	// Transform the vertex from object space to projected world space: 
	OutPos = mul(InPos, 	matWorldViewProj);
	// Pass the texture coordinate to the pixel shader: 
	OutTex = InTex; 
	// Pass the calculated depth to the pixel shader: ... APPARENTLY
}

// Pixel Shader: 
float4 TerrPaintPS(	in float4 InPos: POSITION,	 in float2 InTex: TEXCOORD0,
							in float  Height:TEXCOORD1											): COLOR 
{
	float4 Color;	
			if(Height < 0.16)		Color = tex2D(SandSampler,  InTex); 
	else	if(Height < 0.50)		Color = tex2D(GrassSampler, InTex); 
	else	if(Height < 0.75)		Color = tex2D(RockSampler,  InTex); 
	else 								Color = tex2D(SnowSampler,  InTex);

	
	return Color; 
} 

// Technique: 
technique AmbientTechnique 
{ 
	pass P0 
	{ 
		VertexShader = compile vs_2_0 TerrPaintVS(); 
		PixelShader  = compile ps_2_0 TerrPaintPS(); 
	} 
}