renderer_opengl: Swizzle BGR textures on copy

OpenGL does not natively support BGR internal formats, which causes many BGR textures to render incorrectly, with Red and Blue channels swapped.

This commit aims to address this by swizzling the blue and red channels on texture copies when a BGR format is encountered.

5 files changed, 132 insertions, 2 deletions

diff --git a/src/video_core/host_shaders/CMakeLists.txt b/src/video_core/host_shaders/CMakeLists.txt
index 970120acc..3494318ca 100644
--- a/src/video_core/host_shaders/CMakeLists.txt
+++ b/src/video_core/host_shaders/CMakeLists.txt
@@ -5,6 +5,7 @@ set(SHADER_FILES
     convert_float_to_depth.frag
     full_screen_triangle.vert
     opengl_copy_bc4.comp
+    opengl_copy_bgra.comp
     opengl_present.frag
     opengl_present.vert
     pitch_unswizzle.comp
diff --git a/src/video_core/host_shaders/opengl_copy_bgra.comp b/src/video_core/host_shaders/opengl_copy_bgra.comp
new file mode 100644
index 000000000..2571a4abf
--- /dev/null
+++ b/src/video_core/host_shaders/opengl_copy_bgra.comp
@@ -0,0 +1,15 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#version 430 core
+
+layout (local_size_x = 4, local_size_y = 4) in;
+
+layout(binding = 0, rgba8) readonly uniform image2DArray bgr_input;
+layout(binding = 1, rgba8) writeonly uniform image2DArray bgr_output;
+
+void main() {
+    vec4 color = imageLoad(bgr_input, ivec3(gl_GlobalInvocationID));
+    imageStore(bgr_output, ivec3(gl_GlobalInvocationID), color.bgra);
+}
diff --git a/src/video_core/renderer_opengl/gl_texture_cache.cpp b/src/video_core/renderer_opengl/gl_texture_cache.cpp
index 12434db67..e028677e9 100644
--- a/src/video_core/renderer_opengl/gl_texture_cache.cpp
+++ b/src/video_core/renderer_opengl/gl_texture_cache.cpp
@@ -96,7 +96,7 @@ constexpr std::array<FormatTuple, MaxPixelFormat> FORMAT_TABLE = {{
     {GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT},                          // BC6H_UFLOAT
     {GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT},                            // BC6H_SFLOAT
     {GL_COMPRESSED_RGBA_ASTC_4x4_KHR},                                // ASTC_2D_4X4_UNORM
-    {GL_RGBA8, GL_BGRA, GL_UNSIGNED_BYTE},                            // B8G8R8A8_UNORM
+    {GL_RGBA8, GL_RGBA, GL_UNSIGNED_BYTE},                            // B8G8R8A8_UNORM
     {GL_RGBA32F, GL_RGBA, GL_FLOAT},                                  // R32G32B32A32_FLOAT
     {GL_RGBA32I, GL_RGBA_INTEGER, GL_INT},                            // R32G32B32A32_SINT
     {GL_RG32F, GL_RG, GL_FLOAT},                                      // R32G32_FLOAT
@@ -125,7 +125,7 @@ constexpr std::array<FormatTuple, MaxPixelFormat> FORMAT_TABLE = {{
     {GL_COMPRESSED_RGBA_ASTC_8x8_KHR},                                // ASTC_2D_8X8_UNORM
     {GL_COMPRESSED_RGBA_ASTC_8x5_KHR},                                // ASTC_2D_8X5_UNORM
     {GL_COMPRESSED_RGBA_ASTC_5x4_KHR},                                // ASTC_2D_5X4_UNORM
-    {GL_SRGB8_ALPHA8, GL_BGRA, GL_UNSIGNED_BYTE},                     // B8G8R8A8_UNORM
+    {GL_SRGB8_ALPHA8, GL_RGBA, GL_UNSIGNED_BYTE},                     // B8G8R8A8_SRGB
     {GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT},                         // BC1_RGBA_SRGB
     {GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT},                         // BC2_SRGB
     {GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT},                         // BC3_SRGB
@@ -396,6 +396,17 @@ void AttachTexture(GLuint fbo, GLenum attachment, const ImageView* image_view) {
     }
 }
 
+[[nodiscard]] bool IsPixelFormatBGR(PixelFormat format) {
+    switch (format) {
+    case PixelFormat::B5G6R5_UNORM:
+    case PixelFormat::B8G8R8A8_UNORM:
+    case PixelFormat::B8G8R8A8_SRGB:
+        return true;
+    default:
+        return false;
+    }
+}
+
 } // Anonymous namespace
 
 ImageBufferMap::~ImageBufferMap() {
@@ -512,6 +523,9 @@ bool TextureCacheRuntime::CanImageBeCopied(const Image& dst, const Image& src) {
     if (dst.info.type == ImageType::e3D && dst.info.format == PixelFormat::BC4_UNORM) {
         return false;
     }
+    if (IsPixelFormatBGR(dst.info.format) || IsPixelFormatBGR(src.info.format)) {
+        return false;
+    }
     return true;
 }
 
@@ -520,6 +534,8 @@ void TextureCacheRuntime::EmulateCopyImage(Image& dst, Image& src,
     if (dst.info.type == ImageType::e3D && dst.info.format == PixelFormat::BC4_UNORM) {
         ASSERT(src.info.type == ImageType::e3D);
         util_shaders.CopyBC4(dst, src, copies);
+    } else if (IsPixelFormatBGR(dst.info.format) || IsPixelFormatBGR(src.info.format)) {
+        util_shaders.CopyBGR(dst, src, copies);
     } else {
         UNREACHABLE();
     }
diff --git a/src/video_core/renderer_opengl/util_shaders.cpp b/src/video_core/renderer_opengl/util_shaders.cpp
index 31ec68505..2fe4799bc 100644
--- a/src/video_core/renderer_opengl/util_shaders.cpp
+++ b/src/video_core/renderer_opengl/util_shaders.cpp
@@ -14,6 +14,7 @@
 #include "video_core/host_shaders/block_linear_unswizzle_2d_comp.h"
 #include "video_core/host_shaders/block_linear_unswizzle_3d_comp.h"
 #include "video_core/host_shaders/opengl_copy_bc4_comp.h"
+#include "video_core/host_shaders/opengl_copy_bgra_comp.h"
 #include "video_core/host_shaders/pitch_unswizzle_comp.h"
 #include "video_core/renderer_opengl/gl_resource_manager.h"
 #include "video_core/renderer_opengl/gl_shader_manager.h"
@@ -48,6 +49,11 @@ OGLProgram MakeProgram(std::string_view source) {
     return program;
 }
 
+size_t NumPixelsInCopy(const VideoCommon::ImageCopy& copy) {
+    return static_cast<size_t>(copy.extent.width * copy.extent.height *
+                               copy.src_subresource.num_layers);
+}
+
 } // Anonymous namespace
 
 UtilShaders::UtilShaders(ProgramManager& program_manager_)
@@ -55,6 +61,7 @@ UtilShaders::UtilShaders(ProgramManager& program_manager_)
       block_linear_unswizzle_2d_program(MakeProgram(BLOCK_LINEAR_UNSWIZZLE_2D_COMP)),
       block_linear_unswizzle_3d_program(MakeProgram(BLOCK_LINEAR_UNSWIZZLE_3D_COMP)),
       pitch_unswizzle_program(MakeProgram(PITCH_UNSWIZZLE_COMP)),
+      copy_bgra_program(MakeProgram(OPENGL_COPY_BGRA_COMP)),
       copy_bc4_program(MakeProgram(OPENGL_COPY_BC4_COMP)) {
     const auto swizzle_table = Tegra::Texture::MakeSwizzleTable();
     swizzle_table_buffer.Create();
@@ -205,6 +212,43 @@ void UtilShaders::CopyBC4(Image& dst_image, Image& src_image, std::span<const Im
     program_manager.RestoreGuestCompute();
 }
 
+void UtilShaders::CopyBGR(Image& dst_image, Image& src_image,
+                          std::span<const VideoCommon::ImageCopy> copies) {
+    static constexpr GLuint BINDING_INPUT_IMAGE = 0;
+    static constexpr GLuint BINDING_OUTPUT_IMAGE = 1;
+    static constexpr VideoCommon::Offset3D zero_offset{0, 0, 0};
+    const u32 bytes_per_block = BytesPerBlock(dst_image.info.format);
+    switch (bytes_per_block) {
+    case 2:
+        // BGR565 copy
+        for (const ImageCopy& copy : copies) {
+            ASSERT(copy.src_offset == zero_offset);
+            ASSERT(copy.dst_offset == zero_offset);
+            bgr_copy_pass.Execute(dst_image, src_image, copy);
+        }
+        break;
+    case 4: {
+        // BGRA8 copy
+        program_manager.BindHostCompute(copy_bgra_program.handle);
+        constexpr GLenum FORMAT = GL_RGBA8;
+        for (const ImageCopy& copy : copies) {
+            ASSERT(copy.src_offset == zero_offset);
+            ASSERT(copy.dst_offset == zero_offset);
+            glBindImageTexture(BINDING_INPUT_IMAGE, src_image.StorageHandle(),
+                               copy.src_subresource.base_level, GL_FALSE, 0, GL_READ_ONLY, FORMAT);
+            glBindImageTexture(BINDING_OUTPUT_IMAGE, dst_image.StorageHandle(),
+                               copy.dst_subresource.base_level, GL_FALSE, 0, GL_WRITE_ONLY, FORMAT);
+            glDispatchCompute(copy.extent.width, copy.extent.height, copy.extent.depth);
+        }
+        program_manager.RestoreGuestCompute();
+        break;
+    }
+    default:
+        UNREACHABLE();
+        break;
+    }
+}
+
 GLenum StoreFormat(u32 bytes_per_block) {
     switch (bytes_per_block) {
     case 1:
@@ -222,4 +266,36 @@ GLenum StoreFormat(u32 bytes_per_block) {
     return GL_R8UI;
 }
 
+void Bgr565CopyPass::Execute(const Image& dst_image, const Image& src_image,
+                             const ImageCopy& copy) {
+    if (CopyBufferCreationNeeded(copy)) {
+        CreateNewCopyBuffer(copy, GL_TEXTURE_2D_ARRAY, GL_RGB565);
+    }
+    // Copy from source to PBO
+    glPixelStorei(GL_PACK_ALIGNMENT, 1);
+    glPixelStorei(GL_PACK_ROW_LENGTH, copy.extent.width);
+    glBindBuffer(GL_PIXEL_PACK_BUFFER, bgr16_pbo.handle);
+    glGetTextureSubImage(src_image.Handle(), 0, 0, 0, 0, copy.extent.width, copy.extent.height,
+                         copy.src_subresource.num_layers, GL_RGB, GL_UNSIGNED_SHORT_5_6_5,
+                         static_cast<GLsizei>(bgr16_pbo_size), nullptr);
+
+    // Copy from PBO to destination in reverse order
+    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+    glPixelStorei(GL_UNPACK_ROW_LENGTH, copy.extent.width);
+    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, bgr16_pbo.handle);
+    glTextureSubImage3D(dst_image.Handle(), 0, 0, 0, 0, copy.extent.width, copy.extent.height,
+                        copy.dst_subresource.num_layers, GL_RGB, GL_UNSIGNED_SHORT_5_6_5_REV,
+                        nullptr);
+}
+
+bool Bgr565CopyPass::CopyBufferCreationNeeded(const ImageCopy& copy) {
+    return bgr16_pbo_size < NumPixelsInCopy(copy) * sizeof(u16);
+}
+
+void Bgr565CopyPass::CreateNewCopyBuffer(const ImageCopy& copy, GLenum target, GLuint format) {
+    bgr16_pbo.Create();
+    bgr16_pbo_size = NumPixelsInCopy(copy) * sizeof(u16);
+    glNamedBufferData(bgr16_pbo.handle, bgr16_pbo_size, nullptr, GL_STREAM_COPY);
+}
+
 } // namespace OpenGL
diff --git a/src/video_core/renderer_opengl/util_shaders.h b/src/video_core/renderer_opengl/util_shaders.h
index 7b1d16b09..93b009743 100644
--- a/src/video_core/renderer_opengl/util_shaders.h
+++ b/src/video_core/renderer_opengl/util_shaders.h
@@ -19,6 +19,22 @@ class ProgramManager;
 
 struct ImageBufferMap;
 
+class Bgr565CopyPass {
+public:
+    Bgr565CopyPass() = default;
+    ~Bgr565CopyPass() = default;
+
+    void Execute(const Image& dst_image, const Image& src_image,
+                 const VideoCommon::ImageCopy& copy);
+
+private:
+    [[nodiscard]] bool CopyBufferCreationNeeded(const VideoCommon::ImageCopy& copy);
+    void CreateNewCopyBuffer(const VideoCommon::ImageCopy& copy, GLenum target, GLuint format);
+
+    OGLBuffer bgr16_pbo;
+    size_t bgr16_pbo_size{};
+};
+
 class UtilShaders {
 public:
     explicit UtilShaders(ProgramManager& program_manager);
@@ -36,6 +52,9 @@ public:
     void CopyBC4(Image& dst_image, Image& src_image,
                  std::span<const VideoCommon::ImageCopy> copies);
 
+    void CopyBGR(Image& dst_image, Image& src_image,
+                 std::span<const VideoCommon::ImageCopy> copies);
+
 private:
     ProgramManager& program_manager;
 
@@ -44,7 +63,10 @@ private:
     OGLProgram block_linear_unswizzle_2d_program;
     OGLProgram block_linear_unswizzle_3d_program;
     OGLProgram pitch_unswizzle_program;
+    OGLProgram copy_bgra_program;
     OGLProgram copy_bc4_program;
+
+    Bgr565CopyPass bgr_copy_pass;
 };
 
 GLenum StoreFormat(u32 bytes_per_block);