#include "Macros.fxh"

BEGIN_CONSTANTS

    float4x4 Model                  _vs(c0)             _cb(c0);
    float4x4 ModelViewProjection    _vs(c4)             _cb(c4);

    float3 LightPosition                      _ps(c0)   _cb(c8);
    float FarPlane                            _ps(c1)   _cb(c9);

END_CONSTANTS

struct VertexShaderInput
{
    float4 Position : POSITION;
};

struct VertexShaderOutput
{
    float4 Position : SV_Position;
    float3 PositionWorld : TEXCOORD0;
};

VertexShaderOutput main_vs(VertexShaderInput input)
{
    VertexShaderOutput output;
    output.Position = mul(input.Position, ModelViewProjection);
    output.PositionWorld = mul(input.Position, Model);
    return output;
}

float4 main_ps(VertexShaderOutput input) : SV_TARGET0
{
    float lightDistance = length(input.PositionWorld - LightPosition);
    lightDistance /= FarPlane;
    return float4(lightDistance, 0.0, 0.0, 0.0);
}

Technique SimpleDepth
{
    Pass
    {
        VertexShader = compile vs_3_0 main_vs();
        PixelShader  = compile ps_3_0 main_ps();
    }
}