////////////////////////////////////////////////////////////////////////////////
// Filename: light.ps
////////////////////////////////////////////////////////////////////////////////


/////////////
// GLOBALS //
/////////////
Texture2D shaderTexture : register(t0);
SamplerState SampleType : register(s0);

cbuffer LightBuffer
{
    float4 diffuseColor;
    float3 lightDirection;
	float padding;
};


//////////////
// TYPEDEFS //
//////////////
struct PixelInputType
{
    float4 position : SV_POSITION;
    float2 tex : TEXCOORD0;
	float3 normal : NORMAL;
};


////////////////////////////////////////////////////////////////////////////////
// Pixel Shader
////////////////////////////////////////////////////////////////////////////////
float4 LightPixelShader(PixelInputType input) : SV_TARGET
{
	float4 textureColor;
	float3 lightDir;
	float lightIntensity;
	float4 color;


	// Sample the pixel color from the texture using the sampler at this texture coordinate location.
	textureColor = shaderTexture.Sample(SampleType, input.tex);

	// Invert the light direction for calculations.
    lightDir = -lightDirection;

    // Calculate the amount of light on this pixel.
    lightIntensity = saturate(dot(input.normal, lightDir));

    // Change the diffuse color to red (0, 1, 0)
    float3 greenDiffuseColor = float3(1, 0, 0);

    // Determine the final amount of diffuse color based on the diffuse color combined with the light intensity.
    color = saturate(diffuseColor * lightIntensity);

    // Multiply the texture pixel and the final diffuse color to get the final pixel color result.
	color = color * textureColor;

	return color;
}