From a7417ba84527d57391599d26a1872c035c5e2c48 Mon Sep 17 00:00:00 2001
From: Jeroen Bakker <jbakker>
Date: Fri, 6 May 2022 16:13:57 +0200
Subject: DrawManager: Make instance data persistent.

When resizing a viewport all engine instance data was cleared.
This wasn't the intended design and lead to performance regressions
in the image engine.

This patch makes sure that the instance data isn't cleared when
the viewport size changes. When using instance data, draw engines
are responsible to update the textures accordingly.

This could also reduce flickering/stalling when resizing the viewport
in eevee-next.

Fixes T95428.

Reviewed By: fclem

Maniphest Tasks: T95428

Differential Revision: https://developer.blender.org/D14874
---
 .../blender/draw/engines/image/image_instance_data.hh   |  6 ++++--
 source/blender/draw/engines/image/image_texture_info.hh |  2 ++
 source/blender/draw/intern/draw_view_data.cc            | 17 +++++++----------
 3 files changed, 13 insertions(+), 12 deletions(-)

(limited to 'source/blender/draw')

diff --git a/source/blender/draw/engines/image/image_instance_data.hh b/source/blender/draw/engines/image/image_instance_data.hh
index cb84c7f14ad..358e6fd3bd9 100644
--- a/source/blender/draw/engines/image/image_instance_data.hh
+++ b/source/blender/draw/engines/image/image_instance_data.hh
@@ -75,8 +75,10 @@ struct IMAGE_InstanceData {
       TextureInfo &info = texture_infos[i];
       const bool is_allocated = info.texture != nullptr;
       const bool is_visible = info.visible;
-      const bool should_be_freed = !is_visible && is_allocated;
-      const bool should_be_created = is_visible && !is_allocated;
+      const bool resolution_changed = assign_if_different(info.last_viewport_size,
+                                                          float2(DRW_viewport_size_get()));
+      const bool should_be_freed = is_allocated && (!is_visible || resolution_changed);
+      const bool should_be_created = is_visible && (!is_allocated || resolution_changed);
 
       if (should_be_freed) {
         GPU_texture_free(info.texture);
diff --git a/source/blender/draw/engines/image/image_texture_info.hh b/source/blender/draw/engines/image/image_texture_info.hh
index cd51cdaff3c..9a75941c533 100644
--- a/source/blender/draw/engines/image/image_texture_info.hh
+++ b/source/blender/draw/engines/image/image_texture_info.hh
@@ -46,6 +46,8 @@ struct TextureInfo {
    */
   GPUTexture *texture;
 
+  float2 last_viewport_size = float2(0.0f, 0.0f);
+
   ~TextureInfo()
   {
     if (batch != nullptr) {
diff --git a/source/blender/draw/intern/draw_view_data.cc b/source/blender/draw/intern/draw_view_data.cc
index 0e55d28f6df..3dc28dc9a9a 100644
--- a/source/blender/draw/intern/draw_view_data.cc
+++ b/source/blender/draw/intern/draw_view_data.cc
@@ -88,7 +88,7 @@ void DRW_view_data_default_lists_from_viewport(DRWViewData *view_data, GPUViewpo
                                 });
 }
 
-static void draw_viewport_engines_data_clear(ViewportEngineData *data)
+static void draw_viewport_engines_data_clear(ViewportEngineData *data, bool clear_instance_data)
 {
   DrawEngineType *engine_type = data->engine_type->draw_engine;
   const DrawEngineDataSize *data_size = engine_type->vedata_size;
@@ -103,7 +103,7 @@ static void draw_viewport_engines_data_clear(ViewportEngineData *data)
     MEM_SAFE_FREE(data->stl->storage[i]);
   }
 
-  if (data->instance_data) {
+  if (clear_instance_data && data->instance_data) {
     BLI_assert(engine_type->instance_free != nullptr);
     engine_type->instance_free(data->instance_data);
     data->instance_data = nullptr;
@@ -120,7 +120,7 @@ static void draw_viewport_engines_data_clear(ViewportEngineData *data)
   }
 }
 
-static void draw_view_data_clear(DRWViewData *view_data)
+static void draw_view_data_clear(DRWViewData *view_data, bool free_instance_data)
 {
   GPU_FRAMEBUFFER_FREE_SAFE(view_data->dfbl.default_fb);
   GPU_FRAMEBUFFER_FREE_SAFE(view_data->dfbl.overlay_fb);
@@ -137,23 +137,20 @@ static void draw_view_data_clear(DRWViewData *view_data)
   GPU_TEXTURE_FREE_SAFE(view_data->dtxl.depth_in_front);
 
   for (ViewportEngineData &engine : view_data->engines) {
-    draw_viewport_engines_data_clear(&engine);
+    draw_viewport_engines_data_clear(&engine, free_instance_data);
   }
-
-  view_data->texture_list_size[0] = view_data->texture_list_size[1] = 0;
-  view_data->cache_time = 0.0f;
 }
 
 void DRW_view_data_free(DRWViewData *view_data)
 {
-  draw_view_data_clear(view_data);
+  draw_view_data_clear(view_data, true);
   delete view_data;
 }
 
 void DRW_view_data_texture_list_size_validate(DRWViewData *view_data, const int size[2])
 {
   if (!equals_v2v2_int(view_data->texture_list_size, size)) {
-    draw_view_data_clear(view_data);
+    draw_view_data_clear(view_data, false);
     copy_v2_v2_int(view_data->texture_list_size, size);
   }
 }
@@ -195,7 +192,7 @@ void DRW_view_data_free_unused(DRWViewData *view_data)
 {
   for (ViewportEngineData &engine : view_data->engines) {
     if (view_data->enabled_engines.first_index_of_try(&engine) == -1) {
-      draw_viewport_engines_data_clear(&engine);
+      draw_viewport_engines_data_clear(&engine, false);
     }
   }
 }
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