float4x4 World;
float4x4 View;
float4x4 Projection;

float3 CameraPosition;

Texture SkyBoxTexture;
samplerCUBE SkyBoxSampler = sampler_state //unlike a texture sampler it is a cube instead of 2D
{
	texture = <SkyBoxTexture>;
	magfilter = LINEAR;
	minfilter = LINEAR;
	mipfilter = LINEAR;
	AddressU = Mirror;
	AddressV = Mirror;
};

struct VertexShaderInput
{
	float4 Position : POSITION0;
};

struct VertexShaderOutput
{
	float4 Position : POSITION0;
	float3 TextureCoordinate : TEXCOORD0;
};

VertexShaderOutput VertexShaderFunction(VertexShaderInput input)
{
	VertexShaderOutput output;

	float4 worldPosition = mul(input.Position, World);
	float4 viewPosition = mul(worldPosition, View);
	output.Position = mul(viewPosition, Projection);

	float4 VertexPosition = mul(input.Position, World);
	output.TextureCoordinate = VertexPosition - CameraPosition;

	return output;
}

float4 PixelShaderFunction(VertexShaderOutput input) : COLOR0
{
	return texCUBE(SkyBoxSampler, normalize(input.TextureCoordinate));
}


technique Skybox
{
	pass Pass1
	{
		VertexShader = compile vs_4_0_level_9_3 VertexShaderFunction();
		PixelShader = compile ps_4_0_level_9_3 PixelShaderFunction();
	}
}