Unity URPShader支持多光源处理

news2024/9/20 16:30:56

//声明变体并且引用文件
#pragma shader_feature  _ _ADDITIONAL_LIGHTS_VERTEX _ADDITIONAL_LIGHTS
#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"

//在数据结构体中声明需要使用的数据
struct Attributes
{
   float4 positionOS : POSITION;
   float2 texcoord : TEXCOORD0;
    #if defined(_ENABLELIGHTING_ON)
       float3 normalOS : NORMAL;
    #endif
 };

struct Varyings
{
   float4 positionHS : SV_POSITION;
   float2 uv : TEXCOORD0;

   #if defined(_ENABLELIGHTING_ON)
       half3 lightColor : TEXCOORD1;
        #if defined(_ADDITIONAL_LIGHTS)
            float3 positionWS : TEXCOORD2;
             float3 normalWS : TEXCOORD3;
        #endif
    #endif
};

_ADDITIONAL_LIGHTS_VERTEX 是在顶点Shader中处理平行光额外增加的光源，_ADDITIONAL_LIGHTS是在片元Shader中处理平行光额外增加的光源

 顶点Shader：
//光照
 #if _ENABLELIGHTING_ON
     float3 normalWS = TransformObjectToWorldNormal(v.normalOS.xyz);
     Light main_light = GetMainLight();
     half3 main_light_dir = normalize(main_light.direction);
     half diffuse_term = dot(normalWS, main_light_dir) * 0.5 + 0.5;
     half3 lightColor = diffuse_term * main_light.color;
     
     #ifdef _ADDITIONAL_LIGHTS_VERTEX
         half3 vertexLight = VertexLighting(positionWS, normalWS);
         lightColor += vertexLight;
     #elif _ADDITIONAL_LIGHTS
         o.positionWS = positionWS;
         o.normalWS = normalWS;
         lightColor = half3(0, 0, 0);
     #endif
     o.lightColor = lightColor;
 #endif

片元Shader：
#if _ENABLELIGHTING_ON
    #ifdef _ADDITIONAL_LIGHTS
        uint pixelLightCount = GetAdditionalLightsCount();
        for (uint lightIndex = 0u; lightIndex < pixelLightCount; ++lightIndex)
        {
            Light light = GetAdditionalLight(lightIndex, i.positionWS.xyz);
            half3 attenuatedLightColor = light.color * (light.distanceAttenuation * light.shadowAttenuation);
            i.lightColor += LightingLambert(attenuatedLightColor, light.direction, i.normalWS);
        }
    #endif
    final_color.rgb = i.lightColor * final_color.rgb;
#endif