Light.hlsl

// 灯光数据相关库
#ifndef CUSTOM_LIGHT_INCLUDED
#define CUSTOM_LIGHT_INCLUDED

#define MAX_DIRECTIONAL_LIGHT_COUNT 4

CBUFFER_START(_CustomLight)
    int _DirectionalLightCount;
    // 定向光源颜色、方向、阴影等数据
    float4 _DirectionalLightColors[MAX_DIRECTIONAL_LIGHT_COUNT];
    float4 _DirectionalLightDirections[MAX_DIRECTIONAL_LIGHT_COUNT];
    float4 _DirectionalLightShadowData[MAX_DIRECTIONAL_LIGHT_COUNT];
CBUFFER_END

// 灯光的属性
struct Light
{
    // 颜色
    float3 color;
    // 方向
    float3 direction;
    float attenuation;
};

// 获取方向光源的数量
int GetDirectionalLightCount()
{
    return _DirectionalLightCount;
}

DirectionalShadowData GetDirectionalShadowData(int lightIndex, ShadowData shadowData)
{
    DirectionalShadowData data;
    data.strength = _DirectionalLightShadowData[lightIndex].x * shadowData.strength;
    data.tileIndex = _DirectionalLightShadowData[lightIndex].y + shadowData.cascadeIndex;
    data.normalBias = _DirectionalLightShadowData[lightIndex].z;
    return data;
}

// 获取目标索引定向光的属性
Light GetDirectionalLight(int index, Surface surfaceWS, ShadowData shadowData)
{
    Light light;
    light.color = _DirectionalLightColors[index].rgb;
    light.direction = _DirectionalLightDirections[index].xyz;
    DirectionalShadowData dirShadowData = GetDirectionalShadowData(index, shadowData);
    light.attenuation = GetDirectionalShadowAttenuation(dirShadowData, shadowData, surfaceWS);
    return light;
}

#endif