GPUFrameBuffer: GL backend isolation

This is related to the Vulkan port T68990.

This is a full cleanup of the Framebuffer module and a separation
of OpenGL related functions.

There is some changes with how the default framebuffers are handled.
Now the default framebuffers are individually wrapped inside special
GLFrameBuffers. This make it easier to keep track of the currently bound
framebuffer state and have some specificity for operations on these
framebuffers.

Another change is dropping the optimisation of only configuring the
changed attachements during framebuffers update. This does not give
any benefits and add some complexity to the code. This might be brought
back if it has a performance impact on some systems.

This also adds support for naming framebuffers but it is currently not
used.

1 files changed, 22 insertions, 17 deletions

diff --git a/source/blender/gpu/GPU_framebuffer.h b/source/blender/gpu/GPU_framebuffer.h
index e1526bf50a6..61833a9a65f 100644
--- a/source/blender/gpu/GPU_framebuffer.h
+++ b/source/blender/gpu/GPU_framebuffer.h
@@ -19,6 +19,13 @@
 
 /** \file
  * \ingroup gpu
+ *
+ * GPU Framebuffer
+ * - this is a wrapper for an OpenGL framebuffer object (FBO). in practice
+ *   multiple FBO's may be created.
+ * - actual FBO creation & config is deferred until GPU_framebuffer_bind or
+ *   GPU_framebuffer_check_valid to allow creation & config while another
+ *   opengl context is bound (since FBOs are not shared between ogl contexts).
  */
 
 #pragma once
@@ -41,9 +48,8 @@ typedef enum eGPUFrameBufferBits {
 } eGPUFrameBufferBits;
 
 typedef enum eGPUBackBuffer {
-  GPU_BACKBUFFER = 0,
+  GPU_BACKBUFFER_LEFT = 0,
   GPU_BACKBUFFER_RIGHT,
-  GPU_BACKBUFFER_LEFT,
 } eGPUBackBuffer;
 
 /** Opaque pointer hiding blender::gpu::FrameBuffer. */
@@ -53,15 +59,6 @@ typedef struct GPUFrameBuffer {
 
 typedef struct GPUOffScreen GPUOffScreen;
 
-/* GPU Framebuffer
- * - this is a wrapper for an OpenGL framebuffer object (FBO). in practice
- *   multiple FBO's may be created, to get around limitations on the number
- *   of attached textures and the dimension requirements.
- * - actual FBO creation & config is deferred until GPU_framebuffer_bind or
- *   GPU_framebuffer_check_valid to allow creation & config while another
- *   opengl context is bound (since FBOs are not shared between ogl contexts).
- */
-
 GPUFrameBuffer *GPU_framebuffer_create(void);
 void GPU_framebuffer_free(GPUFrameBuffer *fb);
 void GPU_framebuffer_bind(GPUFrameBuffer *fb);
@@ -72,6 +69,7 @@ bool GPU_framebuffer_bound(GPUFrameBuffer *fb);
 bool GPU_framebuffer_check_valid(GPUFrameBuffer *fb, char err_out[256]);
 
 GPUFrameBuffer *GPU_framebuffer_active_get(void);
+GPUFrameBuffer *GPU_framebuffer_back_get(void);
 
 #define GPU_FRAMEBUFFER_FREE_SAFE(fb) \
   do { \
@@ -84,13 +82,10 @@ GPUFrameBuffer *GPU_framebuffer_active_get(void);
 /* Framebuffer setup : You need to call GPU_framebuffer_bind for these
  * to be effective. */
 
-void GPU_framebuffer_texture_attach(GPUFrameBuffer *fb, struct GPUTexture *tex, int slot, int mip);
-void GPU_framebuffer_texture_layer_attach(
-    GPUFrameBuffer *fb, struct GPUTexture *tex, int slot, int layer, int mip);
-void GPU_framebuffer_texture_cubeface_attach(
-    GPUFrameBuffer *fb, struct GPUTexture *tex, int slot, int face, int mip);
+void GPU_framebuffer_texture_attach_ex(GPUFrameBuffer *gpu_fb,
+                                       GPUAttachment attachement,
+                                       int slot);
 void GPU_framebuffer_texture_detach(GPUFrameBuffer *fb, struct GPUTexture *tex);
-void GPU_framebuffer_texture_detach_slot(GPUFrameBuffer *fb, struct GPUTexture *tex, int type);
 
 /**
  * How to use #GPU_framebuffer_ensure_config().
@@ -155,6 +150,16 @@ void GPU_framebuffer_config_array(GPUFrameBuffer *fb, const GPUAttachment *confi
     _tex, _face, _mip, \
   }
 
+#define GPU_framebuffer_texture_attach(_fb, _texture, _slot, _mip) \
+  GPU_framebuffer_texture_attach_ex( \
+      _fb, (GPUAttachment)GPU_ATTACHMENT_TEXTURE_MIP(_texture, _mip), _slot)
+#define GPU_framebuffer_texture_layer_attach(_fb, _texture, _slot, layer, _mip) \
+  GPU_framebuffer_texture_attach_ex( \
+      _fb, (GPUAttachment)GPU_ATTACHMENT_TEXTURE_LAYER_MIP(_texture, layer, _mip), _slot)
+#define GPU_framebuffer_texture_cubeface_attach(_fb, _texture, _slot, face, _mip) \
+  GPU_framebuffer_texture_attach_ex( \
+      _fb, (GPUAttachment)GPU_ATTACHMENT_TEXTURE_CUBEFACE_MIP(_texture, face, _mip), _slot)
+
 /* Framebuffer operations */
 
 void GPU_framebuffer_viewport_set(GPUFrameBuffer *fb, int x, int y, int w, int h);