From 06a121f7cf6658ea3989b3478b6275ce8c1c7b6d Mon Sep 17 00:00:00 2001
From: mo <michael.oliver_@outlook.com>
Date: Mon, 19 Oct 2026 11:11:10 +0100
Subject: [PATCH] fix: distinguish DDS formats by pixel bit depth (#1048)

Match bit depth as well as channel masks.
---
 src/ObjImage/Image/DdsLoader.cpp             |  7 +++--
 test/ObjCommonTests/Image/DdsLoaderTests.cpp | 32 ++++++++++++++++++++
 2 files changed, 36 insertions(+), 3 deletions(-)
 create mode 100644 test/ObjCommonTests/Image/DdsLoaderTests.cpp

diff --git a/src/ObjImage/Image/DdsLoader.cpp b/src/ObjImage/Image/DdsLoader.cpp
index 8126ef92..fc8af93a 100644
--- a/src/ObjImage/Image/DdsLoader.cpp
+++ b/src/ObjImage/Image/DdsLoader.cpp
@@ -172,9 +172,10 @@ namespace
 
                 const auto* unsignedImageFormat = dynamic_cast<const ImageFormatUnsigned*>(imageFormat);
 
-                if (unsignedImageFormat->m_r_offset == rOffset && unsignedImageFormat->m_r_size == rSize && unsignedImageFormat->m_g_offset == gOffset
-                    && unsignedImageFormat->m_g_size == gSize && unsignedImageFormat->m_b_offset == bOffset && unsignedImageFormat->m_b_size == bSize
-                    && unsignedImageFormat->m_a_offset == aOffset && unsignedImageFormat->m_a_size == aSize)
+                if (unsignedImageFormat->m_bits_per_pixel == pf.dwRGBBitCount && unsignedImageFormat->m_r_offset == rOffset
+                    && unsignedImageFormat->m_r_size == rSize && unsignedImageFormat->m_g_offset == gOffset && unsignedImageFormat->m_g_size == gSize
+                    && unsignedImageFormat->m_b_offset == bOffset && unsignedImageFormat->m_b_size == bSize && unsignedImageFormat->m_a_offset == aOffset
+                    && unsignedImageFormat->m_a_size == aSize)
                 {
                     m_format = imageFormat;
                     return true;
diff --git a/test/ObjCommonTests/Image/DdsLoaderTests.cpp b/test/ObjCommonTests/Image/DdsLoaderTests.cpp
new file mode 100644
index 00000000..f6dc6fd3
--- /dev/null
+++ b/test/ObjCommonTests/Image/DdsLoaderTests.cpp
@@ -0,0 +1,32 @@
+#include "Image/DdsLoader.h"
+#include "Image/DdsWriter.h"
+#include "Image/Texture.h"
+
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/generators/catch_generators.hpp>
+#include <cstring>
+#include <sstream>
+
+TEST_CASE("DDS loading distinguishes BGR pixel strides with identical channel masks", "[image][dds]")
+{
+    const auto* format = GENERATE(&image::format::B8_G8_R8, &image::format::B8_G8_R8_X8);
+    image::Texture2D source(format, 4, 4, true);
+    source.Allocate();
+    for (auto mip = 0; mip < source.GetMipMapCount(); ++mip)
+        for (auto i = 0uz; i < source.GetSizeOfMipLevel(mip); ++i)
+            source.GetBufferForMipLevel(mip, 0)[i] = static_cast<uint8_t>(i * 13 + mip);
+
+    std::stringstream file(std::ios::in | std::ios::out | std::ios::binary);
+    image::DdsWriter writer;
+    writer.DumpImage(file, &source);
+    file.seekg(0);
+    const auto loaded = image::LoadDds(file);
+    REQUIRE(loaded);
+    REQUIRE(loaded->GetFormat()->GetId() == format->GetId());
+    REQUIRE(loaded->GetMipMapCount() == source.GetMipMapCount());
+    for (auto mip = 0; mip < source.GetMipMapCount(); ++mip)
+    {
+        REQUIRE(loaded->GetSizeOfMipLevel(mip) == source.GetSizeOfMipLevel(mip));
+        CHECK(std::memcmp(loaded->GetBufferForMipLevel(mip), source.GetBufferForMipLevel(mip, 0), source.GetSizeOfMipLevel(mip)) == 0);
+    }
+}