void vs_main(
			 // INs
			 in  float3 inPos       : POSITION0,
			 in  float2 inTexCoord  : TEXCOORD0,
			 in  float3 inNormal    : NORMAL0,
			 in  float3 inTangent   : TANGENT0,
			 // OUTs
			 out float4 outPos      : POSITION,
			 out float2 outTexCoord : TEXCOORD0,
			 out float4 outLightDir : TEXCOORD1,
			 // Uniforms
			 uniform float4x4 worldInvTrans,
			 uniform float4x4 worldViewProjection,
			 uniform float terrainTilingFactor,
			 uniform float3 sunlightDir
			 )
{
    float3 n = mul((float3x3)worldInvTrans, inNormal);
	float3 t = mul((float3x3)worldInvTrans, inTangent);
	float3 b = cross(n,t);
	float3x3 tbnMatrix = float3x3(t.x, b.x, n.x,
	                              t.y, b.y, n.y,
	                              t.z, b.z, n.z);

	outPos = mul(worldViewProjection, float4(inPos, 1.0f));

	outTexCoord = inTexCoord * terrainTilingFactor;

	outLightDir.xyz = -sunlightDir;
	outLightDir.xyz = mul(tbnMatrix, outLightDir.xyz);

	// Store the terrain height at this vertex position.
	// The terrain height will be used to generate the terrain texture.
	outLightDir.w = inPos.y;
}