// Define inputs from application.
struct VertexIn
{
  float4 position    : POSITION;   // Vertex in object-space
  float4 normal      : NORMAL;     // Vertex's Normal
  float2 subTexCoord : TEXCOORD0;  // Vertex's Texture Coordinates
  float3 color	     : COLOR0;
};

// Define outputs from vertex shader.
struct Vertex
{
  float4 position       : POSITION;     // Vertex position in screen-space
  float2 texCoord       : TEXCOORD0;    // Vertex texture coordinates
  float2 subTexCoord    : TEXCOORD1;    // Vertex texture coordinates
  float3 normal         : TEXCOORD2;    // Normal in eye-space
  float3 halfVector     : TEXCOORD3;    // Half angle vector in eye space
  float3 lightVector    : TEXCOORD4;    // Light vector in eye space
  float4 wposition      : TEXCOORD5;    // Vertex position in world-space
  float3 color		: COLOR0;
};

Vertex main(VertexIn p_In,
            uniform float4x4 p_ModelViewProjection, // Model view projection matrix
            uniform float4 p_LightPosition,         // Light position in object-space
            uniform float4x4 p_ModelView,           // Model view matrix
            uniform float4x4 p_InverseModelView,    // Model view matrix inverted
	    uniform float4x4 p_Model                // Model matrix
            )
{
    Vertex l_Out;

    // Compute light position in eye-space
    float4 l_LightPosition4 = mul(p_ModelView, p_LightPosition);
    float3 l_LightPosition3 = l_LightPosition4.xyz;
    
    // Compute vertex position in eye-space
    float4 l_Position4 = mul(p_ModelView, p_In.position);
    float3 l_Position3 = l_Position4.xyz / l_Position4.w;
    
    // Transform normal from model-space to eye-space.
    l_Out.normal = mul(p_Model, p_In.normal);
    l_Out.normal = normalize(mul(transpose(p_InverseModelView), float4(l_Out.normal,1.0)).xyz);
    
    // Light vector.
    l_Out.lightVector = l_LightPosition3 - (l_Position3 * l_LightPosition4.w);
    
    // Half angle vector = light vector + eye vector
    l_Out.halfVector = l_Out.lightVector + (- l_Position3);

    // Compute vertex position in light space
    // First object to world space
    l_Out.wposition = mul(p_Model, float4(0.0, 0.0, 0.0, 1.0));

    // Transform vertex position into homogenous screen-space.
    l_Out.position = mul(p_ModelViewProjection, p_In.position);

    // Pass texture coordinates to fragment shader
    l_Out.subTexCoord = p_In.subTexCoord;
    l_Out.texCoord = p_In.color.xy;

    l_Out.color = p_In.color;

    return l_Out;
}