texture2D elevationTexture;
sampler2D elevationSampler = sampler_state
{
	texture = <elevationTexture>;
	MipFilter = Linear;
	MagFilter = Linear;
	MinFilter = Linear;
	AddressU = CLAMP;
	AddressV = CLAMP;
}; 

texture2D terrainTexture;
sampler2D terrainSampler = sampler_state
{
	texture = <terrainTexture>;
	MipFilter = Linear;
	MagFilter = Linear;
	MinFilter = Linear;
	AddressU = WRAP;
	AddressV = WRAP;
}; 

float3 eyeDirection;
float fp;
float bp;

struct vsTerrainInput
{
	float4  pos		: POSITION;
};

float getTerrainHeight(float3 pos)
{
	float2 d = sin(pos.xz / 100.0);
	for(int ni=0; ni<4; ni++)
		d = float2(d.x*d.x - d.y * d.y + 0.45, 2 * d.x * d.y + 0.3);
	return 1/(dot(d, d) + 1) * 20.1 - 10.0;
}

struct vsTerrainOutput
{
	float4 pos			: POSITION;
	float3 normal		: NORMAL;
	float3 worldPos		: TEXCOORD0;
	float3 tangent		: TEXCOORD1;
	float3 binormal		: TEXCOORD2;
	float3 eyeRayDir	: TEXCOORD4;
	
	float2 bumpCoord	: TEXCOORD3;
};

vsTerrainOutput vsTerrain(vsTerrainInput input)
{
	vsTerrainOutput output = (vsTerrainOutput)0;
	output.bumpCoord.xy = input.pos.xz*0.006;
	
//	input.pos.y = tex2Dlod(elevationSampler, float4(input.pos.xz, 0, 1)) - 0.5;
	input.pos.y = cos(input.pos.x * 12.0) - 0.01;
	
	input.pos.xyz *= float3(1000.0, 10.0, 1000.0);
	
	output.worldPos = input.pos.xyz;

	float3 du = float3(1, 0, 0);
	float3 dv = float3(0, 0, 1);
	
	output.pos = mul(float4(input.pos.xyz, 1), viewProjMatrix);

	output.binormal = normalize(du) * 0.3;
	output.tangent  = normalize(dv) * 0.3;
	output.normal   = normalize(cross(dv,du));
	
	return output;
}

float4 psTerrain(vsTerrainOutput input) : COLOR0
{
/*	input.worldPos.y = 0;
	input.eyeRayDir = normalize(input.eyeRayDir);
	for(int r=0; r<15; r++)
		input.worldPos -= input.eyeRayDir * (getTerrainHeight(input.worldPos) - input.worldPos.y);

	input.worldPos.y = getTerrainHeight(input.worldPos);
	depth = (dot(input.worldPos - eyePosition, eyeDirection) - fp)/(bp-fp);*/
	
	half4 t0 = tex2D(terrainSampler, input.bumpCoord) * 2 - 1;
	half3 N = t0.xzy;
	
	half3x3 m;
	m[0] = input.tangent;
	m[2] = input.binormal;
	m[1] = input.normal;
	
	half3 normalWorld = mul(m, N);
	normalWorld = normalize(normalWorld);
	
	float3 viewDir = -normalize(eyePosition - input.worldPos);

	return float4(1, (input.worldPos.y + 5) / 20, 0, 1);
}

technique terrain
{
	pass P0
	{
		VertexShader = compile vs_3_0 vsTerrain();
		PixelShader = compile ps_3_0 psTerrain();
	}	
};