GPUFramebuffer: Refactor (Part 2)

This refactor modernise the use of framebuffers.
It also touches a lot of files so breaking down changes we have:
 - GPUTexture: Allow textures to be attached to more than one GPUFrameBuffer.
   This allows to create and configure more FBO without the need to attach
   and detach texture at drawing time.
 - GPUFrameBuffer: The wrapper starts to mimic opengl a bit closer. This
   allows to configure the framebuffer inside a context other than the one
   that will be rendering the framebuffer. We do the actual configuration
   when binding the FBO. We also Keep track of config validity and save
   drawbuffers state in the FBO. We remove the different bind/unbind
   functions. These make little sense now that we have separate contexts.
 - DRWFrameBuffer: We replace DRW_framebuffer functions by GPU_framebuffer
   ones to avoid another layer of abstraction. We move the DRW convenience
   functions to GPUFramebuffer instead and even add new ones. The MACRO
   GPU_framebuffer_ensure_config is pretty much all you need to create and
   config a GPUFramebuffer.
 - DRWTexture: Due to the removal of DRWFrameBuffer, we needed to create
   functions to create textures for thoses framebuffers. Pool textures are
   now using default texture parameters for the texture type asked.
 - DRWManager: Make sure no framebuffer object is bound when doing cache
   filling.
 - GPUViewport: Add new color_only_fb and depth_only_fb along with FB API
   usage update. This let draw engines render to color/depth only target
   and without the need to attach/detach textures.
 - WM_window: Assert when a framebuffer is bound when changing context.
   This balance the fact we are not track ogl context inside GPUFramebuffer.
 - Eevee, Clay, Mode engines: Update to new API. This comes with a lot of
   code simplification.

This also come with some cleanups in some engine codes.

1 files changed, 86 insertions, 20 deletions

diff --git a/source/blender/gpu/GPU_framebuffer.h b/source/blender/gpu/GPU_framebuffer.h
index 93f16b342d1..0ab15a4ea47 100644
--- a/source/blender/gpu/GPU_framebuffer.h
+++ b/source/blender/gpu/GPU_framebuffer.h
@@ -36,6 +36,13 @@
 extern "C" {
 #endif
 
+struct GPUTexture;
+
+typedef struct GPUAttachment {
+	struct GPUTexture *tex;
+	int mip, layer;
+} GPUAttachment;
+
 typedef enum GPUFrameBufferBits{
 	GPU_COLOR_BIT    = (1 << 0),
 	GPU_DEPTH_BIT    = (1 << 1),
@@ -44,40 +51,95 @@ typedef enum GPUFrameBufferBits{
 
 typedef struct GPUFrameBuffer GPUFrameBuffer;
 typedef struct GPUOffScreen GPUOffScreen;
-struct GPUTexture;
 
 /* 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.
- * - after any of the GPU_framebuffer_* functions, GPU_framebuffer_restore must
- *   be called before rendering to the window framebuffer again */
-
-void GPU_texture_bind_as_framebuffer(struct GPUTexture *tex);
+ * - 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);
-bool GPU_framebuffer_texture_attach(GPUFrameBuffer *fb, struct GPUTexture *tex, int slot, int mip);
-bool GPU_framebuffer_texture_layer_attach(
-        GPUFrameBuffer *fb, struct GPUTexture *tex, int slot, int layer, int mip);
-bool GPU_framebuffer_texture_cubeface_attach(
-        GPUFrameBuffer *fb, struct GPUTexture *tex, int slot, int face, int mip);
-void GPU_framebuffer_texture_detach(struct GPUTexture *tex);
-void GPU_framebuffer_bind(GPUFrameBuffer *fb);
-void GPU_framebuffer_slots_bind(GPUFrameBuffer *fb, int slot);
-void GPU_framebuffer_texture_unbind(GPUFrameBuffer *fb, struct GPUTexture *tex);
 void GPU_framebuffer_free(GPUFrameBuffer *fb);
+void GPU_framebuffer_bind(GPUFrameBuffer *fb);
+void GPU_framebuffer_restore(void);
+
+bool GPU_framebuffer_bound(GPUFrameBuffer *fb);
 bool GPU_framebuffer_check_valid(GPUFrameBuffer *fb, char err_out[256]);
 
 /* internal use only */
 unsigned int GPU_framebuffer_current_get(void);
-void GPU_framebuffer_bind_no_save(GPUFrameBuffer *fb, int slot);
 
-bool GPU_framebuffer_bound(GPUFrameBuffer *fb);
+#define GPU_FRAMEBUFFER_FREE_SAFE(fb) do { \
+	if (fb != NULL) { \
+		GPU_framebuffer_free(fb); \
+		fb = NULL; \
+	} \
+} while (0)
+
+/* Framebuffer setup : You need to call GPU_framebuffer_bind for theses
+ * 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_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().
+ *
+ * Example :
+ * GPU_framebuffer_ensure_config(&fb, {
+ *         GPU_ATTACHMENT_TEXTURE(depth), // must be depth buffer
+ *         GPU_ATTACHMENT_TEXTURE(tex1),
+ *         GPU_ATTACHMENT_TEXTURE_CUBEFACE(tex2, 0),
+ *         GPU_ATTACHMENT_TEXTURE_LAYER_MIP(tex2, 0, 0)
+ * })
+ *
+ * Note : Unspecified attachements (i.e: those beyond the last
+ *        GPU_ATTACHMENT_* in GPU_framebuffer_ensure_config list)
+ *        are left unchanged.
+ * Note : Make sure that the dimensions of your textures matches
+ *        otherwise you will have an invalid framebuffer error.
+ **/
+#define GPU_framebuffer_ensure_config(_fb, ...) do { \
+	if (*(_fb) == NULL) { \
+		*(_fb) = GPU_framebuffer_create(); \
+	} \
+	GPUAttachment config[] = __VA_ARGS__; \
+	GPU_framebuffer_config_array(*(_fb), config, (sizeof(config) / sizeof(GPUAttachment))); \
+} while (0)
+
+void GPU_framebuffer_config_array(GPUFrameBuffer *fb, const GPUAttachment *config, int config_ct);
+
+#define GPU_ATTACHMENT_NONE \
+        {.tex = NULL, .layer = -1, .mip = 0}
+#define GPU_ATTACHMENT_LEAVE \
+        {.tex = NULL, .layer = -1, .mip = -1}
+#define GPU_ATTACHMENT_TEXTURE(_tex) \
+        {.tex = _tex, .layer = -1, .mip = 0}
+#define GPU_ATTACHMENT_TEXTURE_MIP(_tex, _mip) \
+        {.tex = _tex, .layer = -1, .mip = _mip}
+#define GPU_ATTACHMENT_TEXTURE_LAYER(_tex, _layer) \
+        {.tex = _tex, .layer = _layer, .mip = 0}
+#define GPU_ATTACHMENT_TEXTURE_LAYER_MIP(_tex, _layer, _mip) \
+        {.tex = _tex, .layer = _layer, .mip = _mip}
+#define GPU_ATTACHMENT_TEXTURE_CUBEFACE(_tex, _face) \
+        {.tex = _tex, .layer = _face, .mip = 0}
+#define GPU_ATTACHMENT_TEXTURE_CUBEFACE_MIP(_tex, _face, _mip) \
+        {.tex = _tex, .layer = _face, .mip = _mip}
+
 /* Framebuffer operations */
 
 void GPU_framebuffer_viewport_set(GPUFrameBuffer *fb, int x, int y, int w, int h);
 
-void GPU_framebuffer_restore(void);
 void GPU_framebuffer_clear(
         GPUFrameBuffer *fb, GPUFrameBufferBits buffers,
         const float clear_col[4], float clear_depth, unsigned int clear_stencil);
@@ -100,18 +162,22 @@ void GPU_framebuffer_clear(
 #define GPU_framebuffer_clear_color_depth_stencil(fb, col, depth, stencil) \
         GPU_framebuffer_clear(fb, GPU_COLOR_BIT | GPU_DEPTH_BIT | GPU_STENCIL_BIT, col, depth, stencil)
 
+void GPU_framebuffer_read_depth(GPUFrameBuffer *fb, int x, int y, int w, int h, float *data);
+void GPU_framebuffer_read_color(
+        GPUFrameBuffer *fb, int x, int y, int w, int h, int channels, int slot, float *data);
 
 void GPU_framebuffer_blit(
         GPUFrameBuffer *fb_read, int read_slot,
-        GPUFrameBuffer *fb_write, int write_slot, bool use_depth, bool use_stencil);
+        GPUFrameBuffer *fb_write, int write_slot,
+        GPUFrameBufferBits blit_buffers);
 
 void GPU_framebuffer_recursive_downsample(
-        GPUFrameBuffer *fb, struct GPUTexture *tex, int num_iter,
+        GPUFrameBuffer *fb, int max_lvl,
         void (*callback)(void *userData, int level), void *userData);
 
 /* GPU OffScreen
  * - wrapper around framebuffer and texture for simple offscreen drawing
- * - changes size if graphics card can't support it */
+ */
 
 GPUOffScreen *GPU_offscreen_create(int width, int height, int samples,
         bool depth, bool high_bitdepth, char err_out[256]);