// Diffuse lighting model
// I=Aintensity*Acolour + Dintensity*Dcolour * N.L
// Where
// Aintensity is the ambient light intensity
// Acolour is the colour of the ambient light
// Dintensity is the Diffuse light intensity
// Dcolour is the colour of the Diffuse light
// N is the surface normal
// L is the light direction
// These lines are just for EffectEdit:
string XFile = "tiny\\tiny.x";  
int    BCLR = 0xff202080;       
float4 vecLightDir < string UIDirectional = "Light Direction"; > = normalize(float4(0.0f, 0.0f, 1.0f,0.0f));
// transformations provided by the app as input:
float4x4 matWorldViewProj: WORLDVIEWPROJECTION;
float4x4 matWorld  : WORLD;
// the format of our vertex data
struct VS_OUTPUT
{
    float4 Pos : POSITION;
    float3 Light : TEXCOORD0;
    float3 Norm : TEXCOORD1;
};
// Vertex Shader - carry out transformations
VS_OUTPUT VS(float4 Pos : POSITION, float3 Normal : NORMAL)
{
    VS_OUTPUT Out = (VS_OUTPUT)0; 
    Out.Pos = mul(Pos, matWorldViewProj); // transform Position
    Out.Light = normalize(vecLightDir); // output light vector
    Out.Norm = -normalize(mul(Normal, matWorld)); // transform Normal and normalize it 
    return Out;
}
// Calculate the diffuse light component, add it to the ambient
// light component and return the colour value
float4 PS(float3 Light: TEXCOORD0, float3 Norm : TEXCOORD1) : COLOR
{
    // Intensity of ambient light:
    float Aintensity=0.2f;
    // The colour of the ambient light:
    float4 Acolour=float4(0.1,0.1,0.1,1.0);
    // Define variable for the intensity and colour
    float Dintensity=1.0f;
    float4 Dcolour=float4(1.0,0.6,0.6,1.0);
    // Calculate the result using the light vector (Light)
    // and normal (Norm), using the dot product
    float4 result=Dintensity*Dcolour*(dot(Norm,Light));
    // Add the diffuse result to the ambient below for return
    return Aintensity*Acolour+result;
}
// Effect technique to be used
technique TVertexAndPixelShader
{
    pass P0
    {
        // shaders
        VertexShader = compile vs_1_1 VS();
        PixelShader  = compile ps_1_1 PS();
    }  
}