float4x4 WorldViewProj; //World * View * Projection
float4x4 World;         //World
float4x4 TexTransform;  //Texture transformation matrix
float3 EyePos;          //World position of the camera
float Ambient = 0.0f;   //Amount of ambient light
float LightFalloff;

texture LightTex;
texture ColorTex;

//Must be clamped so the light texture shows up only once
sampler LightTexSampler = sampler_state
{
    Texture = <LightTex>;
    MinFilter = LINEAR;  
    MagFilter = LINEAR;
    MipFilter = LINEAR;
    AddressU  = Clamp;
    AddressV  = Clamp;
};

sampler ColorTexSampler = sampler_state
{
    Texture = <ColorTex>;
    MinFilter = LINEAR;  
    MagFilter = LINEAR;
    MipFilter = LINEAR;
    AddressU  = Wrap;
    AddressV  = Wrap;
};

////////////////////////////////////////////////////////////
// Structures
////////////////////////////////////////////////////////////
struct MainA2V{
    float4 Position : POSITION;
    float2 TexCoord0 : TEXCOORD0;
};

struct MainV2P{
    float4 Position  : POSITION;
    float2 TexCoord0 : TEXCOORD0;
    float4 TexCoord1 : TEXCOORD1;
    float  Attn      : TEXCOORD2;
};

////////////////////////////////////////////////////////////
// Vertex Shaders
////////////////////////////////////////////////////////////
void MainVS(in MainA2V IN, out MainV2P OUT)
{
    //Copy color texture coordinates through
    OUT.TexCoord0 = IN.TexCoord0;
    
    //First two are the projected texture coordinates
    OUT.TexCoord1 = mul(IN.Position, TexTransform);
    
    //Position to light vector
    float3 LightVec = mul(IN.Position.xyz, (float3x3)World) - EyePos;
    
    //Distance from position to light
    float Dist = dot(LightVec, LightVec);
    
    //Compute attenuation
    OUT.Attn = (LightFalloff * LightFalloff)/Dist;
    
    //Transform model-space vertex position to screen space:
    OUT.Position = mul(IN.Position, WorldViewProj);
}

////////////////////////////////////////////////////////////
// Pixel Shader
////////////////////////////////////////////////////////////
float4 MainPS(in MainV2P IN) : COLOR 
{
    //Read in values for shadow, light texture and color texture
    float4 Color    = tex2D(ColorTexSampler, IN.TexCoord0);
    float4 Light    = tex2D(LightTexSampler, IN.TexCoord1);
    
    //Compute lighting amount
    float4 I = (Light * IN.Attn) + Ambient;
    
    //Color of texture * lighting amount
    return I * Color;
}

////////////////////////////////////////////////////////////
// Techniques
////////////////////////////////////////////////////////////
technique ProjectiveTexture
{
    pass P0
    {
        VertexShader = compile vs_1_1 MainVS();
        PixelShader = compile ps_1_1 MainPS();
    
        TextureTransformFlags[0] = Projected;
        TextureTransformFlags[1] = Projected;
    }
}