//ThinFilm.cg

//============================================================================
// define inputs from application
//============================================================================
struct a2v
{
    float4 Position : POSITION;
    float3 Normal   : NORMAL;
};

//============================================================================
// define outputs from vertex shader
//============================================================================
struct v2f
{
    float4 HPOS      : POSITION;
    float4 diffCol   : COLOR0;
    float4 specCol   : COLOR1;
    float2 filmDepth : TEXCOORD0;
};

//============================================================================
// The main function
//============================================================================
v2f main(a2v IN,
             uniform float4x4 WorldViewProj,
             uniform float4x4 WorldViewIT,
             uniform float4x4 WorldView,
             uniform float4 LightVector,
             uniform float4 FilmDepth,
             uniform float4 EyeVector)
{
    v2f OUT;

    //transform position to clip space
    OUT.HPOS = mul(WorldViewProj, IN.Position);

    float4 tempnorm = float4(IN.Normal, 0.0);

    // transform normal from model-space to view-space
    float3 normalVec = mul(WorldViewIT, tempnorm).xyz;
    normalVec = normalize(normalVec);

    // compute the eye->vertex vector
    float3 eyeVec = EyeVector.xyz;   //infinite viewer (Best looking)

    // compute the view depth for the thin film
    float viewdepth = (1.0 / dot(normalVec, eyeVec)) * FilmDepth.x;

    OUT.filmDepth = viewdepth.xx;

    // store normalized light vector
    float3 lightVec = normalize((float3)LightVector);

    // calculate half angle vector
    float3 halfAngleVec = normalize(lightVec + eyeVec);

    // calculate diffuse component
    float diffuse = dot(normalVec, lightVec);

    // calculate specular component
    float specular = dot(normalVec, halfAngleVec);

    // use the lit instruction to calculate lighting, automatically clamp
    float4 lighting = lit(diffuse, specular, 32);

    // output final lighting results
    OUT.diffCol = (float4)lighting.y;
    OUT.specCol = (float4)lighting.z;

    return OUT;
}

//--------------------------------------------

struct v2f
{
    float3 diffCol   : COLOR0;
    float3 specCol   : COLOR1;
    float2 filmDepth : TEXCOORD0;
};

void main( v2f IN,
             out float4 color : COLOR,
             uniform sampler2D fringeMap,
             uniform sampler2D diffMap)
{
    // diffuse material color
    float3 diffCol  = float3(0.3, 0.3, 0.5);

    // lookup fringe value based on view depth
    float3 fringeCol = (float3)tex2D(fringeMap, IN.filmDepth);

    // modulate specular lighting by fringe color, combine with regular lighting
    color.rgb = fringeCol*IN.specCol + IN.diffCol*diffCol;
    color.a = 1.0;
}