Texture loader: added option to premultiply color channels by alpha

DiligentGraphics · Sep 1, 2023 · 7bcd2b1 · 7bcd2b1
1 parent cb6a888
commit 7bcd2b1
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Showing 4 changed files with 27 additions and 0 deletions.
diff --git a/TextureLoader/interface/Image.h b/TextureLoader/interface/Image.h
@@ -69,6 +69,14 @@ struct ImageLoadInfo
 {
     /// Image file format
     IMAGE_FILE_FORMAT Format DEFAULT_INITIALIZER(IMAGE_FILE_FORMAT_UNKNOWN);
+
+    /// Whether to premultiply RGB channels by alpha
+    bool PermultiplyAlpha DEFAULT_INITIALIZER(false);
+
+    /// Whether the image is stored in sRGB format
+    ///
+    /// \note This flag is only used if PermultiplyAlpha is true.
+    bool IsSRGB DEFAULT_INITIALIZER(false);
 };
 typedef struct ImageLoadInfo ImageLoadInfo;
 

diff --git a/TextureLoader/interface/TextureLoader.h b/TextureLoader/interface/TextureLoader.h
@@ -82,6 +82,9 @@ struct TextureLoadInfo
     /// Flag indicating that the image should be flipped vertically
     Bool FlipVertically                 DEFAULT_VALUE(False);
 
+    /// Flag indicating that RGB channels should be premultiplied by alpha
+    Bool PermultiplyAlpha               DEFAULT_VALUE(False);
+
     /// Texture format
     TEXTURE_FORMAT Format               DEFAULT_VALUE(TEX_FORMAT_UNKNOWN);
 

diff --git a/TextureLoader/src/Image.cpp b/TextureLoader/src/Image.cpp
@@ -46,6 +46,7 @@
 #include "GraphicsAccessories.hpp"
 #include "BasicFileStream.hpp"
 #include "StringTools.hpp"
+#include "TextureUtilities.h"
 
 namespace Diligent
 {
@@ -259,6 +260,19 @@ Image::Image(IReferenceCounters*  pRefCounters,
     {
         LOG_ERROR_MESSAGE("Unknown image format.");
     }
+
+    if (LoadInfo.PermultiplyAlpha && m_Desc.NumComponents == 4)
+    {
+        PremultiplyAlphaAttribs PremultAttribs;
+        PremultAttribs.Width          = m_Desc.Width;
+        PremultAttribs.Height         = m_Desc.Height;
+        PremultAttribs.ComponentType  = m_Desc.ComponentType;
+        PremultAttribs.ComponentCount = m_Desc.NumComponents;
+        PremultAttribs.Stride         = m_Desc.RowStride;
+        PremultAttribs.pPixels        = m_pData->GetDataPtr();
+        PremultAttribs.IsSRGB         = LoadInfo.IsSRGB;
+        PremultiplyAlpha(PremultAttribs);
+    }
 }
 
 void Image::CreateFromDataBlob(IDataBlob*           pFileData,

diff --git a/TextureLoader/src/TextureLoaderImpl.cpp b/TextureLoader/src/TextureLoaderImpl.cpp
@@ -146,6 +146,8 @@ TextureLoaderImpl::TextureLoaderImpl(IReferenceCounters*        pRefCounters,
         {
             m_pDataBlob = DataBlobImpl::Create(DataSize, pData);
         }
+        ImgLoadInfo.IsSRGB           = TexLoadInfo.IsSRGB;
+        ImgLoadInfo.PermultiplyAlpha = TexLoadInfo.PermultiplyAlpha;
         Image::CreateFromDataBlob(m_pDataBlob, ImgLoadInfo, &m_pImage);
         LoadFromImage(TexLoadInfo);
         m_pDataBlob.Release();