//direction of the light
float3 lightDirection;

//color of the light 
float3 Color; 

//position of the camera, for specular light
float3 cameraPosition; 
float3 lightPosition;

float4x4 LightViewProjection;

//this is used to compute the world-position
float4x4 InvertViewProjection; 

// diffuse color, and specularIntensity in the alpha channel
texture colorMap; 
// normals, and specularPower in the alpha channel
texture normalMap;
//depth
texture depthMap;
// shadow
texture shadowMap;

sampler shadowSampler = sampler_state
{
    Texture = (shadowMap);
    AddressU = CLAMP;
    AddressV = CLAMP;
    MagFilter = LINEAR;
    MinFilter = LINEAR;
    Mipfilter = LINEAR;
};
sampler colorSampler = sampler_state
{
    Texture = (colorMap);
    AddressU = CLAMP;
    AddressV = CLAMP;
    MagFilter = LINEAR;
    MinFilter = LINEAR;
    Mipfilter = LINEAR;
};
sampler depthSampler = sampler_state
{
    Texture = (depthMap);
    AddressU = CLAMP;
    AddressV = CLAMP;
    MagFilter = POINT;
    MinFilter = POINT;
    Mipfilter = POINT;
};
sampler normalSampler = sampler_state
{
    Texture = (normalMap);
    AddressU = CLAMP;
    AddressV = CLAMP;
    MagFilter = POINT;
    MinFilter = POINT;
    Mipfilter = POINT;
};

struct VertexShaderInput
{
    float3 Position : POSITION0;
    float2 TexCoord : TEXCOORD0;
};

struct VertexShaderOutput
{
    float4 Position : POSITION0;
    float2 TexCoord : TEXCOORD0;
};

float2 halfPixel;

VertexShaderOutput VertexShaderFunction(VertexShaderInput input)
{
    VertexShaderOutput output;
    output.Position = float4(input.Position,1);
    //align texture coordinates
    output.TexCoord = input.TexCoord - halfPixel;
    return output;
}

float4 PixelShaderFunction(VertexShaderOutput input) : COLOR0
{
    //get normal data from the normalMap
    float4 normalData = tex2D(normalSampler,input.TexCoord);
    //tranform normal back into [-1,1] range
    float3 normal = 2.0f * normalData.xyz - 1.0f;

    //read depth
    float depthVal = tex2D(depthSampler,input.TexCoord).r;
        
    //compute screen-space position
    float4 position;
    position.x = input.TexCoord.x * 2.0f - 1.0f;
    position.y = -(input.TexCoord.y * 2.0f - 1.0f);
    position.z = depthVal;
    position.w = 1.0f;

    //transform to world space
    position = mul(position, InvertViewProjection);
    
	float4 projection = mul(position, LightViewProjection);
	
	float2 projectedTexCoords;
	
    projectedTexCoords[0] = projection.x / projection.w / 2.0f + 0.5f;
    projectedTexCoords[1] = -projection.y / projection.w / 2.0f + 0.5f;
    
    float4 moments = tex2D(shadowSampler, projectedTexCoords);
    
    float len = length(lightPosition - position) / 10000;
    
    float depthBias = (1.0f / 200.0f);
    
    float4 color = 1;
    
    if(len - depthBias > moments.r)
    {
		color = 0;
    }
    
	return color;
}

technique Technique0
{
    pass Pass0
    {
        VertexShader = compile vs_2_0 
        VertexShaderFunction();
        PixelShader = compile ps_2_0 
        PixelShaderFunction();
    }
}