Image: Partial Update Redesign.

This patch reimplements the image partial updates. Biggest design motivation for the redesign
is that currently GPUTextures must be owned by the image. This reduces flexibility and adds
complexity to a single component especially when we want to have different structures.

The new design is not limited to GPUTextures and can also be used by reducing overhead in image
operations like scaling. Or partial image updating in Cycles.

The usecase in hand is that we want to support virtual images in the image editor so we can
work with images that don't fit in a single GPUTexture.

Using `BKE_image_partial_update_mark_region` or `BKE_image_partial_update_mark_full_update`
a part of an image can be marked as dirty. These regions are stored per ImageTile (UDIM).

When a part of the code wants to receive partial changes it needs to construct a `PartialUpdateUser`
by calling `BKE_image_partial_update_create`. As long as this instance is kept alive the changes can
be received.

When a user wants to update its own data it will call `BKE_image_partial_update_collect_changes`
This will collect the changes since the last time the user called this function. When the partial changes
are available the partial change can be read by calling `BKE_image_partial_update_get_next_change`

It can happen that the introduced mechanism doesn't have the data anymore to construct the
changes since the last time a PartialUpdateUser requested it. In this case it will get a request
to perform a full update.

Maniphest Tasks: T92613

Differential Revision: https://developer.blender.org/D13238

1 files changed, 13 insertions, 7 deletions

diff --git a/source/blender/makesdna/DNA_image_types.h b/source/blender/makesdna/DNA_image_types.h
index 64c8fd3e3a9..7a789227128 100644
--- a/source/blender/makesdna/DNA_image_types.h
+++ b/source/blender/makesdna/DNA_image_types.h
@@ -142,10 +142,20 @@ typedef enum eImageTextureResolution {
   IMA_TEXTURE_RESOLUTION_LEN
 } eImageTextureResolution;
 
+/* Defined in BKE_image.h. */
+struct PartialUpdateRegister;
+struct PartialUpdateUser;
+
 typedef struct Image_Runtime {
   /* Mutex used to guarantee thread-safe access to the cached ImBuf of the corresponding image ID.
    */
   void *cache_mutex;
+
+  /** \brief Register containing partial updates. */
+  struct PartialUpdateRegister *partial_update_register;
+  /** \brief Partial update user for GPUTextures stored inside the Image. */
+  struct PartialUpdateUser *partial_update_user;
+
 } Image_Runtime;
 
 typedef struct Image {
@@ -171,8 +181,6 @@ typedef struct Image {
   int lastframe;
 
   /* GPU texture flag. */
-  /* Contains `ImagePartialRefresh`. */
-  ListBase gpu_refresh_areas;
   int gpuframenr;
   short gpuflag;
   short gpu_pass;
@@ -247,15 +255,13 @@ enum {
 enum {
   /** GPU texture needs to be refreshed. */
   IMA_GPU_REFRESH = (1 << 0),
-  /** GPU texture needs to be partially refreshed. */
-  IMA_GPU_PARTIAL_REFRESH = (1 << 1),
   /** All mipmap levels in OpenGL texture set? */
-  IMA_GPU_MIPMAP_COMPLETE = (1 << 2),
+  IMA_GPU_MIPMAP_COMPLETE = (1 << 1),
   /* Reuse the max resolution textures as they fit in the limited scale. */
-  IMA_GPU_REUSE_MAX_RESOLUTION = (1 << 3),
+  IMA_GPU_REUSE_MAX_RESOLUTION = (1 << 2),
   /* Has any limited scale textures been allocated.
    * Adds additional checks to reuse max resolution images when they fit inside limited scale. */
-  IMA_GPU_HAS_LIMITED_SCALE_TEXTURES = (1 << 4),
+  IMA_GPU_HAS_LIMITED_SCALE_TEXTURES = (1 << 3),
 };
 
 /* Image.source, where the image comes from */