//Application fed data
const float4x4 matWorldViewProj;


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 											)	 
{ 
	// Transform the vertex from object space to projected world space: 
	OutPos = mul(InPos, 	matWorldViewProj);
	// Pass the texture coordinate to the pixel shader: 
	OutTex = InTex; 
	// Capture the Height of this vertex from object space... SEEMINGLY
	Height = abs(1-(InPos.y/InPos.w));
}

// Pixel Shader: 
float4 TerrPaintPS(	in float4 InPos: POSITION,	 in float2 InTex: TEXCOORD0,
							in float  Height:TEXCOORD1											): COLOR 
{
	float4 Color;

		if(Height <  16)		Color = tex2D(SandSampler,  InTex); 
	else	if(Height <  26)		Color = lerp(tex2D(SandSampler,InTex), tex2D(GrassSampler,InTex), 0.5);
	else	if(Height <  50)		Color = tex2D(GrassSampler, InTex); 
	else	if(Height <  55)		Color = lerp(tex2D(GrassSampler,InTex), tex2D(RockSampler,InTex), 0.5);
	else	if(Height <  75)		Color = tex2D(RockSampler,  InTex); 
	else	if(Height <  85)		Color = lerp(tex2D(RockSampler,InTex), tex2D(SnowSampler,InTex), 0.5);
	else 					Color = tex2D(SnowSampler,  InTex);



	return Color; 
} 

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