PBR_Render: Improved computing of IBL textures

DiligentGraphics · May 7, 2024 · f0a1094 · f0a1094
1 parent 525ee5e
commit f0a1094
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Showing 3 changed files with 18 additions and 5 deletions.
diff --git a/PBR/interface/PBR_Renderer.hpp b/PBR/interface/PBR_Renderer.hpp
@@ -680,9 +680,9 @@ class PBR_Renderer
     RefCntAutoPtr<ITextureView> m_pDefaultNormalMapSRV;
     RefCntAutoPtr<ITextureView> m_pDefaultPhysDescSRV;
 
-    static constexpr TEXTURE_FORMAT IrradianceCubeFmt    = TEX_FORMAT_RGBA32_FLOAT;
+    static constexpr TEXTURE_FORMAT IrradianceCubeFmt    = TEX_FORMAT_RGBA16_FLOAT;
     static constexpr TEXTURE_FORMAT PrefilteredEnvMapFmt = TEX_FORMAT_RGBA16_FLOAT;
-    static constexpr Uint32         IrradianceCubeDim    = 64;
+    static constexpr Uint32         IrradianceCubeDim    = 16;
     static constexpr Uint32         PrefilteredEnvMapDim = 256;
 
     RefCntAutoPtr<ITextureView>           m_pIrradianceCubeSRV;

diff --git a/PBR/src/PBR_Renderer.cpp b/PBR/src/PBR_Renderer.cpp
@@ -387,14 +387,17 @@ PBR_Renderer::~PBR_Renderer()
 void PBR_Renderer::PrecomputeBRDF(IDeviceContext* pCtx,
                                   Uint32          NumBRDFSamples)
 {
+
+    bool IsSupportedUnormFormat = m_Device.GetTextureFormatInfo(TEX_FORMAT_RG16_UNORM).Supported;
+
     TextureDesc TexDesc;
     TexDesc.Name            = "Preintegrated GGX";
     TexDesc.Type            = RESOURCE_DIM_TEX_2D;
     TexDesc.Usage           = USAGE_DEFAULT;
     TexDesc.BindFlags       = BIND_SHADER_RESOURCE | BIND_RENDER_TARGET;
     TexDesc.Width           = BRDF_LUT_Dim;
     TexDesc.Height          = BRDF_LUT_Dim;
-    TexDesc.Format          = TEX_FORMAT_RG16_FLOAT;
+    TexDesc.Format          = IsSupportedUnormFormat ? TEX_FORMAT_RG16_UNORM : TEX_FORMAT_RG16_FLOAT;
     TexDesc.MipLevels       = 1;
     auto pPreintegratedGGX  = m_Device.CreateTexture(TexDesc);
     m_pPreintegratedGGX_SRV = pPreintegratedGGX->GetDefaultView(TEXTURE_VIEW_SHADER_RESOURCE);
@@ -498,6 +501,7 @@ void PBR_Renderer::PrecomputeCubemaps(IDeviceContext* pCtx,
         ShaderMacroHelper Macros;
         Macros.AddShaderMacro("NUM_PHI_SAMPLES", static_cast<int>(NumPhiSamples));
         Macros.AddShaderMacro("NUM_THETA_SAMPLES", static_cast<int>(NumThetaSamples));
+        Macros.AddShaderMacro("IRRADIANCE_MAP_DIMENSION", static_cast<int>(IrradianceCubeDim));
         ShaderCI.Macros = Macros;
         RefCntAutoPtr<IShader> pVS;
         {

diff --git a/Shaders/PBR/private/ComputeIrradianceMap.psh b/Shaders/PBR/private/ComputeIrradianceMap.psh
@@ -8,14 +8,23 @@
 #   define NUM_THETA_SAMPLES 32
 #endif
 
+#ifndef IRRADIANCE_MAP_DIMENSION
+#   define IRRADIANCE_MAP_DIMENSION 16
+#endif
+
 TextureCube  g_EnvironmentMap;
 SamplerState g_EnvironmentMap_sampler;
 
 void main(in float4 Pos      : SV_Position,
           in float3 WorldPos : WORLD_POS,
           out float4 Color   : SV_Target)
 {
-    float3 N     = normalize(WorldPos);
+
+    uint3 TextureDimension;
+    g_EnvironmentMap.GetDimensions(0, TextureDimension.x, TextureDimension.y, TextureDimension.z);    
+    float EnvLod = max(0.0, log2(float(max(TextureDimension.x, TextureDimension.y) / IRRADIANCE_MAP_DIMENSION)) - 1.0);
+
+    float3 N = normalize(WorldPos);
     float3 up    = float3(0.0, 1.0, 0.0);
     float3 right = normalize(cross(up, N));
     up = cross(N, right);
@@ -34,7 +43,7 @@ void main(in float4 Pos      : SV_Position,
             float theta = float(t) * deltaTheta;
             float3 tempVec   = cos(phi) * right + sin(phi) * up;
             float3 sampleDir = cos(theta) * N + sin(theta) * tempVec;
-            color += g_EnvironmentMap.Sample(g_EnvironmentMap_sampler, sampleDir).rgb * cos(theta) * sin(theta);
+            color += g_EnvironmentMap.SampleLevel(g_EnvironmentMap_sampler, sampleDir, EnvLod).rgb * cos(theta) * sin(theta);
             sampleCount += 1.0;
         }
     }