// celshading.ps
cbuffer LightBuffer
{
    float4 diffuseColor;
    float3 lightDirection;
    float padding; // Padding to ensure the structure is a multiple of 16 bytes.
};

Texture2D shaderTexture;
SamplerState SampleType;

struct PixelInputType
{
    float4 position : SV_POSITION;
    float2 tex : TEXCOORD0;
};

float4 CelShadingPixelShader(PixelInputType input) : SV_TARGET
{
    float4 textureColor;
    float lightIntensity;
    float4 finalColor;

    // Sample the pixel color from the texture.
    textureColor = shaderTexture.Sample(SampleType, input.tex);

    // Calculate the light intensity based on the light direction.
    lightIntensity = saturate(dot(normalize(lightDirection), float3(0.0f, 0.0f, -1.0f)));

    // Apply a step function to create the cel shading effect.
    if (lightIntensity > 0.5f)
    {
        lightIntensity = 1.0f;
    }
    else
    {
        lightIntensity = 0.3f;
    }

    // Calculate the final color by combining the texture color with the light intensity and diffuse color.
    finalColor = textureColor * diffuseColor * lightIntensity;

    return finalColor;
}