From 899563165e0c93d29f2ae0942421d566672cab55 Mon Sep 17 00:00:00 2001
From: Swung0x48 <swung0x48@outlook.com>
Date: Fri, 14 Nov 2025 17:08:55 +0800
Subject: [PATCH] [Feat] (MG_Backend/DirectGLES): hook up `glDrawBuffers`

---
 MobileGL/MG_Backend/DirectGLES/Managers.cpp     | 17 +++++++++++++++++
 .../FramebufferState/FramebufferObject.cpp      |  8 ++++----
 .../FramebufferState/FramebufferObject.h        |  6 ++++--
 3 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/MobileGL/MG_Backend/DirectGLES/Managers.cpp b/MobileGL/MG_Backend/DirectGLES/Managers.cpp
index 0293a1ea..658e9d55 100644
--- a/MobileGL/MG_Backend/DirectGLES/Managers.cpp
+++ b/MobileGL/MG_Backend/DirectGLES/Managers.cpp
@@ -423,6 +423,23 @@ namespace MobileGL::MG_Backend::DirectGLES {
                     // TODO
                 }
             }
+
+            if (stateFBOObject->DrawBuffersIsDirty()) {
+                static GLenum drawbufs[MG_State::GLState::FramebufferObject::MAX_DRAW_BUFFERS];
+                std::fill(drawbufs, drawbufs + MG_State::GLState::FramebufferObject::MAX_DRAW_BUFFERS, GL_NONE);
+                auto& stateDrawBuffers = stateFBOObject->GetDrawBuffers();
+                GLint i = 0;
+                for (; i < stateDrawBuffers.size(); ++i) {
+                    if (stateDrawBuffers[i] == FramebufferAttachmentType::None) {
+                        break;
+                    }
+                    drawbufs[i] = MG_Util::ConvertFramebufferAttachmentTypeToGLEnum(stateDrawBuffers[i]);
+                }
+
+                MG_External::GLES::glDrawBuffers(i, drawbufs);
+
+                stateFBOObject->ClearDrawBuffersDirtyState();
+            }
         }
 
         UnorderedMap<SharedPtr<MG_State::GLState::FramebufferObject>, SharedPtr<BackendFramebufferObject>>
diff --git a/MobileGL/MG_State/GLState/FramebufferState/FramebufferObject.cpp b/MobileGL/MG_State/GLState/FramebufferState/FramebufferObject.cpp
index 127eb719..3ac66fbd 100644
--- a/MobileGL/MG_State/GLState/FramebufferState/FramebufferObject.cpp
+++ b/MobileGL/MG_State/GLState/FramebufferState/FramebufferObject.cpp
@@ -72,18 +72,18 @@ namespace MobileGL {
             void FramebufferObject::AttachTexture(FramebufferAttachmentType type, SharedPtr<ITextureObject> texture,
                                                   int level) {
                 m_attachments[static_cast<SizeT>(type)] = FramebufferAttachment(std::move(texture), level);
-                m_drawBuffersDirty = true;
+//                m_drawBuffersDirty = true;
             }
 
             void FramebufferObject::AttachRenderbuffer(FramebufferAttachmentType type,
                                                        std::shared_ptr<RenderbufferObjectStub> renderbuffer) {
                 m_attachments[static_cast<SizeT>(type)] = FramebufferAttachment(renderbuffer);
-                m_drawBuffersDirty = true;
+//                m_drawBuffersDirty = true;
             }
 
             void FramebufferObject::Detach(FramebufferAttachmentType type) {
                 m_attachments[static_cast<SizeT>(type)] = FramebufferAttachment(false);
-                m_drawBuffersDirty = true;
+//                m_drawBuffersDirty = true;
             }
 
             const FramebufferAttachment& FramebufferObject::GetAttachment(FramebufferAttachmentType type) const {
@@ -143,7 +143,7 @@ namespace MobileGL {
 //
 //            }
 
-            const auto& FramebufferObject::GetDrawBuffers() const {
+            const Array<FramebufferAttachmentType, FramebufferObject::MAX_DRAW_BUFFERS>& FramebufferObject::GetDrawBuffers() const {
                 return m_drawBuffers;
             }
 
diff --git a/MobileGL/MG_State/GLState/FramebufferState/FramebufferObject.h b/MobileGL/MG_State/GLState/FramebufferState/FramebufferObject.h
index 7f4f85a5..84c53d04 100644
--- a/MobileGL/MG_State/GLState/FramebufferState/FramebufferObject.h
+++ b/MobileGL/MG_State/GLState/FramebufferState/FramebufferObject.h
@@ -105,7 +105,9 @@ namespace MobileGL {
                 Bool CheckCompleteness() const;
 //                void SetDrawBuffers(const Vector<FramebufferAttachmentType>& buffers);
                 void SetDrawBuffer(Uint index, FramebufferAttachmentType buffer);
-                const auto& GetDrawBuffers() const;
+                bool DrawBuffersIsDirty() const { return m_drawBuffersDirty; }
+                void ClearDrawBuffersDirtyState() { m_drawBuffersDirty = false; }
+                const Array<FramebufferAttachmentType, MAX_DRAW_BUFFERS>& GetDrawBuffers() const;
                 Uint GetExternalIndex() const;
 
             private:
@@ -113,7 +115,7 @@ namespace MobileGL {
                 Array<FramebufferAttachment,
                       static_cast<SizeT>(FramebufferAttachmentType::FramebufferAttachmentTypeCount)>
                     m_attachments;
-                Bool m_drawBuffersDirty = true;
+                Bool m_drawBuffersDirty = false;
                 Array<FramebufferAttachmentType, MAX_DRAW_BUFFERS> m_drawBuffers;
             };