TerrainVS.hlsl

// The variables defined in this cbuffer will pull their data from the 
// constant buffer (ID3D11Buffer) bound to "vertex shader constant buffer slot 0"
// It was bound using context->VSSetConstantBuffers() over in C++.
cbuffer ExternalData : register(b0)
{
	float4 colorTint;
	matrix world;
	matrix view;
	matrix proj;
}

// Struct representing a single vertex worth of data
struct VertexShaderInput
{
	// Data type
	//  |
	//  |   Name          Semantic
	//  |    |                |
	//  v    v                v
	float3 position		: POSITION;     // XYZ position
	float2 uv			: TEXCOORD;
	float3 normal		: NORMAL;
	float3 tangent		: TANGENT;
};

// Struct representing the data we're sending down the pipeline
struct VertexToPixel
{
	// Data type
	//  |
	//  |   Name          Semantic
	//  |    |                |
	//  v    v                v
	float4 position		: SV_POSITION;	// XYZW position (System Value Position)
	float4 color		: COLOR;        // RGBA color
	float2 uv			: TEXCOORD;
	float3 normal		: NORMAL;
	float3 tangent		: TANGENT;
	float3 worldPos		: POSITION;
};

// --------------------------------------------------------
// The entry point (main method) for our vertex shader
// --------------------------------------------------------
VertexToPixel main(VertexShaderInput input)
{
	// Set up output struct
	VertexToPixel output;

	// Modifying the position using the provided transformation (world) matrix
	matrix wvp = mul(proj, mul(view, world));
	output.position = mul(wvp, float4(input.position, 1.0f));

	// Calculate the final world position of the vertex
	output.worldPos = mul(world, float4(input.position, 1.0f)).xyz;

	// Modify the normal so its also in world space
	output.normal = mul((float3x3)world, input.normal);
	output.normal = normalize(output.normal);

	// Modify the tangent much like the normal
	output.tangent = mul((float3x3)world, input.tangent);
	output.tangent = normalize(output.tangent);

	// Tints the color before passing it through
	output.color = colorTint;
	output.uv = input.uv;

	// Whatever we return will make its way through the pipeline to the
	// next programmable stage we're using (the pixel shader for now)
	return output;
}