From 05fe7479994a507249c744f395ab3d876f81aeac Mon Sep 17 00:00:00 2001
From: gamebabyrocksun <41750362@qq.com>
Date: Mon, 20 Mar 2023 13:39:56 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=E4=BA=86=E7=A4=BA=E4=BE=8B25?=
 =?UTF-8?q?=E4=B8=AD=E6=9C=80=E7=BB=88=20IBL=20=E5=90=88=E6=88=90=E5=85=89?=
 =?UTF-8?q?=E7=85=A7Shader=20=E4=B8=AD=E7=9A=84=E6=B3=A8=E9=87=8A?=
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---
 .../25-IBL-MultiInstance-Sphere.cpp               |  4 ++--
 .../Shader/GRS_PBR_IBL_PS_Without_Texture.hlsl    | 15 ++++++++++++---
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/25-IBL-MultiInstance-Sphere/25-IBL-MultiInstance-Sphere.cpp b/25-IBL-MultiInstance-Sphere/25-IBL-MultiInstance-Sphere.cpp
index c654ce4..18dfbc0 100644
--- a/25-IBL-MultiInstance-Sphere/25-IBL-MultiInstance-Sphere.cpp
+++ b/25-IBL-MultiInstance-Sphere/25-IBL-MultiInstance-Sphere.cpp
@@ -4386,9 +4386,9 @@ int APIENTRY _tWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCm
 
             float fOffsetX = 2.0f;
             float fOffsetY = fOffsetX;
-            float fWidth = 240.f;
+            float fWidth = 180.f;
             float fHeight = fWidth;
-            size_t szCol = 8;
+            size_t szCol = 10;
 
             for (size_t i = 0; i < g_stQuadData.m_nInstanceCount; i++)
             {
diff --git a/25-IBL-MultiInstance-Sphere/Shader/GRS_PBR_IBL_PS_Without_Texture.hlsl b/25-IBL-MultiInstance-Sphere/Shader/GRS_PBR_IBL_PS_Without_Texture.hlsl
index 98fb60a..49e1950 100644
--- a/25-IBL-MultiInstance-Sphere/Shader/GRS_PBR_IBL_PS_Without_Texture.hlsl
+++ b/25-IBL-MultiInstance-Sphere/Shader/GRS_PBR_IBL_PS_Without_Texture.hlsl
@@ -73,18 +73,27 @@ float4 PSMain(ST_GRS_HLSL_PBR_PS_INPUT stPSInput): SV_TARGET
     float3 kS = F;
     float3 kD = 1.0 - kS;
     kD *= 1.0 - stPSInput.m_fMetallic;
-
+    // 采样漫反射辐照度贴图
     float3 irradiance = g_texDiffuseCubemap.Sample(g_sapLinear, N).rgb;
+    
+    // 与物体表面点P的颜色值相乘
     float3 diffuse = irradiance * stPSInput.m_v3Albedo;
 
     // IBL镜面反射环境光部分
-    const float MAX_REFLECTION_LOD = 4.0;
+    const float MAX_REFLECTION_LOD = 5.0; // 与镜面反射预积分贴图的 Max Map Level 保持一致
+    // 采样镜面反射预积分辐照度贴图
     float3 prefilteredColor = g_texSpecularCubemap.SampleLevel(g_sapLinear, R, stPSInput.m_fRoughness * MAX_REFLECTION_LOD).rgb;
+    
+    // 采样 BRDF 预积分贴图
     float2 brdf = g_texLut.Sample(g_sapLinear, float2(max(dot(N, V), 0.0), stPSInput.m_fRoughness)).rg;
+    
+    // 合成计算镜面反射光辐射度，注意使用的是 F0 参数，与公式保持一致
     float3 specular = prefilteredColor * (F0 * brdf.x + brdf.y);
 
-    // IBL 光照合成
+    // IBL 光照合成，注意用 kD 参数再衰减下漫反射成分，与最开初的渲染方程中保持一致
+    // m_fA0 是环境遮挡因子，目前总是设置其为 1
     float3 ambient = (kD * diffuse + specular) * stPSInput.m_fAO;
+
     // 直接光照 + IBL光照
     float3 color = ambient + Lo;
 
-- 
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