struct VS_SpotOut
{
	float4 position : POSITION;
	float2 texCoord : TEXCOORD0;
	float3 interPos : TEXCOORD1;
	float att : TEXCOORD2;
	float3 lightVec : TEXCOORD4;
	float3 lightDir : TEXCOORD6;
};

struct VS_SpotIn
{
	float4 position : POSITION0;
	float2 texCoord : TEXCOORD0;

};

float CalculateFallOff(float alpha)
{
	float result;
	
	float nom = cos(alpha) - cos(phi);
	float donom = cos(theta) - cos(phi);
	result = pow(nom/donom,1);
	
	return result;
};
VS_SpotOut VS_Spot(VS_SpotIn input, uniform int CurrentLight)
{
	VS_SpotOut output;
	float4x4 wvp = mul(mul(World, View), Projection);
	output.position = mul(input.position, wvp);
	output.interPos = mul(input.position, World);
	output.lightDir = mul(-lightDirection, World);
	output.texCoord = input.texCoord;

	output.lightVec = lightPosition[CurrentLight] - output.interPos.xyz;
	output.att = 1-(1/pow(length(output.lightVec),4));
		
	return output;
}

float4 PS_Spot(VS_SpotOut input) : COLOR
{
	float4 FinalColor = {0.0f,0.0f,0.0f,1.0f};
	
	float4 TextureColor = tex2D(ColoredTextureSampler,input.texCoord);
	
	float alpha;

	alpha = acos(dot(input.lightVec,input.lightDir)/(length(input.lightVec)*length(input.lightDir)));  
		
	if (alpha < phi && alpha > theta)
	{
		FinalColor =  input.att * (CalculateFallOff(alpha) * (TextureColor)) ;
	}
	else if (alpha < theta)
	{
		FinalColor =  input.att * (TextureColor) ;
	}
	
	FinalColor.a = 1.0;
	return FinalColor ;
}
technique SpotLight
{
	
    pass Pass0
    {
        VertexShader = compile vs_2_0 VS_Spot(0);
        PixelShader = compile ps_2_0 PS_Spot();
    }
    pass Pass1
    {
        VertexShader = compile vs_2_0 VS_Spot(1);
        PixelShader = compile ps_2_0 PS_Spot();
    }
    
}