DrawManager: Image engine support huge images.

Adding better support for drawing huge images in the image/uv editor. Also solved tearing artifacts.
The approach is that for each image/uv editor a screen space gpu texture is created that only contains
the visible pixels. When zooming or panning the gpu texture is rebuild.

Although the solution isn't memory intensive other parts of blender memory usage scales together with
the image size.

* Due to complexity we didn't implement partial updates when drawing images tiled (wrap repeat).
  This could be added, but is complicated as a change in the source could mean many different
  changes on the GPU texture. The work around for now is to tag all gpu textures to be dirty when
  changes are detected.

Original plan was to have 4 screen space images to support panning without gpu texture creation.
For now we don't see the need to implement it as the solution is already fast. Especially when
GPU memory is shared with CPU ram.

Reviewed By: fclem

Maniphest Tasks: T92525, T92903

Differential Revision: https://developer.blender.org/D13424

1 files changed, 41 insertions, 31 deletions

diff --git a/source/blender/draw/engines/image/image_engine.cc b/source/blender/draw/engines/image/image_engine.cc
index be5946f34eb..840d4840f1b 100644
--- a/source/blender/draw/engines/image/image_engine.cc
+++ b/source/blender/draw/engines/image/image_engine.cc
@@ -41,7 +41,7 @@
 
 #include "GPU_batch.h"
 
-#include "image_drawing_mode_image_space.hh"
+#include "image_drawing_mode.hh"
 #include "image_engine.h"
 #include "image_private.hh"
 #include "image_space_image.hh"
@@ -68,7 +68,7 @@ template<
      *
      * Useful during development to switch between drawing implementations.
      */
-    typename DrawingMode = ImageSpaceDrawingMode>
+    typename DrawingMode = ScreenSpaceDrawingMode<OneTextureMethod>>
 class ImageEngine {
  private:
   const DRWContextState *draw_ctx;
@@ -86,48 +86,58 @@ class ImageEngine {
 
   void cache_init()
   {
-    IMAGE_StorageList *stl = vedata->stl;
-    IMAGE_PrivateData *pd = stl->pd;
-
+    IMAGE_InstanceData *instance_data = vedata->instance_data;
     drawing_mode.cache_init(vedata);
-    pd->view = nullptr;
-    if (space->has_view_override()) {
-      const ARegion *region = draw_ctx->region;
-      pd->view = space->create_view_override(region);
-    }
+
+    /* Setup full screen view matrix. */
+    const ARegion *region = draw_ctx->region;
+    float winmat[4][4], viewmat[4][4];
+    orthographic_m4(viewmat, 0.0, region->winx, 0.0, region->winy, 0.0, 1.0);
+    unit_m4(winmat);
+    instance_data->view = DRW_view_create(viewmat, winmat, nullptr, nullptr, nullptr);
   }
 
   void cache_populate()
   {
-    IMAGE_StorageList *stl = vedata->stl;
-    IMAGE_PrivateData *pd = stl->pd;
+    IMAGE_InstanceData *instance_data = vedata->instance_data;
     Main *bmain = CTX_data_main(draw_ctx->evil_C);
-    pd->image = space->get_image(bmain);
-    if (pd->image == nullptr) {
+    instance_data->image = space->get_image(bmain);
+    if (instance_data->image == nullptr) {
       /* Early exit, nothing to draw. */
       return;
     }
-    pd->ibuf = space->acquire_image_buffer(pd->image, &pd->lock);
+    instance_data->flags.do_tile_drawing = instance_data->image->source != IMA_SRC_TILED &&
+                                           space->use_tile_drawing();
+    void *lock;
+    ImBuf *image_buffer = space->acquire_image_buffer(instance_data->image, &lock);
+
+    /* Setup the matrix to go from screen UV coordinates to UV texture space coordinates. */
+    float image_resolution[2] = {image_buffer ? image_buffer->x : 1024.0f,
+                                 image_buffer ? image_buffer->y : 1024.0f};
+    space->init_ss_to_texture_matrix(
+        draw_ctx->region, image_resolution, instance_data->ss_to_texture);
+
+    const Scene *scene = DRW_context_state_get()->scene;
+    instance_data->sh_params.update(space.get(), scene, instance_data->image, image_buffer);
+    space->release_buffer(instance_data->image, image_buffer, lock);
+
     ImageUser *iuser = space->get_image_user();
-    drawing_mode.cache_image(space.get(), vedata, pd->image, iuser, pd->ibuf);
+    drawing_mode.cache_image(vedata, instance_data->image, iuser);
   }
 
   void draw_finish()
   {
     drawing_mode.draw_finish(vedata);
 
-    IMAGE_StorageList *stl = vedata->stl;
-    IMAGE_PrivateData *pd = stl->pd;
-    space->release_buffer(pd->image, pd->ibuf, pd->lock);
-    pd->image = nullptr;
-    pd->ibuf = nullptr;
+    IMAGE_InstanceData *instance_data = vedata->instance_data;
+    instance_data->image = nullptr;
   }
 
   void draw_scene()
   {
     drawing_mode.draw_scene(vedata);
   }
-};
+};  // namespace blender::draw::image_engine
 
 /* -------------------------------------------------------------------- */
 /** \name Engine Callbacks
@@ -137,15 +147,9 @@ static void IMAGE_engine_init(void *ved)
 {
   IMAGE_shader_library_ensure();
   IMAGE_Data *vedata = (IMAGE_Data *)ved;
-  IMAGE_StorageList *stl = vedata->stl;
-  if (!stl->pd) {
-    stl->pd = static_cast<IMAGE_PrivateData *>(MEM_callocN(sizeof(IMAGE_PrivateData), __func__));
+  if (vedata->instance_data == nullptr) {
+    vedata->instance_data = MEM_new<IMAGE_InstanceData>(__func__);
   }
-  IMAGE_PrivateData *pd = stl->pd;
-
-  pd->ibuf = nullptr;
-  pd->lock = nullptr;
-  pd->texture = nullptr;
 }
 
 static void IMAGE_cache_init(void *vedata)
@@ -174,6 +178,12 @@ static void IMAGE_engine_free()
   IMAGE_shader_free();
 }
 
+static void IMAGE_instance_free(void *_instance_data)
+{
+  IMAGE_InstanceData *instance_data = reinterpret_cast<IMAGE_InstanceData *>(_instance_data);
+  MEM_delete(instance_data);
+}
+
 /** \} */
 
 static const DrawEngineDataSize IMAGE_data_size = DRW_VIEWPORT_DATA_SIZE(IMAGE_Data);
@@ -191,7 +201,7 @@ DrawEngineType draw_engine_image_type = {
     &IMAGE_data_size,      /* vedata_size */
     &IMAGE_engine_init,    /* engine_init */
     &IMAGE_engine_free,    /* engine_free */
-    nullptr,               /* instance_free */
+    &IMAGE_instance_free,  /* instance_free */
     &IMAGE_cache_init,     /* cache_init */
     &IMAGE_cache_populate, /* cache_populate */
     nullptr,               /* cache_finish */