[Bf-blender-cvs] [439f86ac89b] temp-T97272: Fix T97272: Lag when resizing viewports.

[Jeroen Bakker]

Commit: 439f86ac89bdd649aa9ccfe258c5f80474788449
Author: Jeroen Bakker
Date:   Tue May 10 08:10:46 2022 +0200
Branches: temp-T97272
https://developer.blender.org/rB439f86ac89bdd649aa9ccfe258c5f80474788449

Fix T97272: Lag when resizing viewports.

Viewports where cleared explicitly due to compatibility reasons with Intel iGPUs.
This slowed down other platforms as well, this wasn't noticeable on all platforms.

This patch will be more selective when to enable the workaround.
Currently only for iGPUs on Mac + Linux.

===================================================================

M	source/blender/gpu/GPU_capabilities.h
M	source/blender/gpu/intern/gpu_capabilities.cc
M	source/blender/gpu/intern/gpu_capabilities_private.hh
M	source/blender/gpu/intern/gpu_viewport.c
M	source/blender/gpu/opengl/gl_backend.cc

===================================================================

diff --git a/source/blender/gpu/GPU_capabilities.h b/source/blender/gpu/GPU_capabilities.h
index 0d0542aa528..aedac168a01 100644
--- a/source/blender/gpu/GPU_capabilities.h
+++ b/source/blender/gpu/GPU_capabilities.h
@@ -40,6 +40,7 @@ bool GPU_mip_render_workaround(void);
 bool GPU_depth_blitting_workaround(void);
 bool GPU_use_main_context_workaround(void);
 bool GPU_use_hq_normals_workaround(void);
+bool GPU_clear_viewport_workaround(void);
 bool GPU_crappy_amd_driver(void);
 
 bool GPU_compute_shader_support(void);
diff --git a/source/blender/gpu/intern/gpu_capabilities.cc b/source/blender/gpu/intern/gpu_capabilities.cc
index b750dacaca6..72b62b3de3d 100644
--- a/source/blender/gpu/intern/gpu_capabilities.cc
+++ b/source/blender/gpu/intern/gpu_capabilities.cc
@@ -142,6 +142,11 @@ bool GPU_use_hq_normals_workaround()
   return GCaps.use_hq_normals_workaround;
 }
 
+bool GPU_clear_viewport_workaround()
+{
+  return GCaps.clear_viewport_workaround;
+}
+
 bool GPU_compute_shader_support()
 {
   return GCaps.compute_shader_support;
diff --git a/source/blender/gpu/intern/gpu_capabilities_private.hh b/source/blender/gpu/intern/gpu_capabilities_private.hh
index 4a951eb8458..611c2d6973c 100644
--- a/source/blender/gpu/intern/gpu_capabilities_private.hh
+++ b/source/blender/gpu/intern/gpu_capabilities_private.hh
@@ -51,6 +51,7 @@ struct GPUCapabilities {
   bool use_main_context_workaround = false;
   bool broken_amd_driver = false;
   bool use_hq_normals_workaround = false;
+  bool clear_viewport_workaround = false;
   /* Vulkan related workarounds. */
 
   /* Metal related workarounds. */
diff --git a/source/blender/gpu/intern/gpu_viewport.c b/source/blender/gpu/intern/gpu_viewport.c
index a0efe12f523..d528160797d 100644
--- a/source/blender/gpu/intern/gpu_viewport.c
+++ b/source/blender/gpu/intern/gpu_viewport.c
@@ -21,6 +21,7 @@
 #include "DNA_userdef_types.h"
 #include "DNA_vec_types.h"
 
+#include "GPU_capabilities.h"
 #include "GPU_framebuffer.h"
 #include "GPU_immediate.h"
 #include "GPU_matrix.h"
@@ -126,19 +127,23 @@ static void gpu_viewport_textures_create(GPUViewport *viewport)
   if (viewport->color_render_tx[0] == NULL) {
     viewport->color_render_tx[0] = GPU_texture_create_2d(
         "dtxl_color", UNPACK2(size), 1, GPU_RGBA16F, NULL);
-    GPU_texture_clear(viewport->color_render_tx[0], GPU_DATA_FLOAT, empty_pixel);
     viewport->color_overlay_tx[0] = GPU_texture_create_2d(
         "dtxl_color_overlay", UNPACK2(size), 1, GPU_SRGB8_A8, NULL);
-    GPU_texture_clear(viewport->color_overlay_tx[0], GPU_DATA_FLOAT, empty_pixel);
+    if (GPU_clear_viewport_workaround()) {
+      GPU_texture_clear(viewport->color_render_tx[0], GPU_DATA_FLOAT, empty_pixel);
+      GPU_texture_clear(viewport->color_overlay_tx[0], GPU_DATA_FLOAT, empty_pixel);
+    }
   }
 
   if ((viewport->flag & GPU_VIEWPORT_STEREO) != 0 && viewport->color_render_tx[1] == NULL) {
     viewport->color_render_tx[1] = GPU_texture_create_2d(
         "dtxl_color_stereo", UNPACK2(size), 1, GPU_RGBA16F, NULL);
-    GPU_texture_clear(viewport->color_render_tx[1], GPU_DATA_FLOAT, empty_pixel);
     viewport->color_overlay_tx[1] = GPU_texture_create_2d(
         "dtxl_color_overlay_stereo", UNPACK2(size), 1, GPU_SRGB8_A8, NULL);
-    GPU_texture_clear(viewport->color_overlay_tx[1], GPU_DATA_FLOAT, empty_pixel);
+    if (GPU_clear_viewport_workaround()) {
+      GPU_texture_clear(viewport->color_render_tx[1], GPU_DATA_FLOAT, empty_pixel);
+      GPU_texture_clear(viewport->color_overlay_tx[1], GPU_DATA_FLOAT, empty_pixel);
+    }
   }
 
   /* Can be shared with GPUOffscreen. */
diff --git a/source/blender/gpu/opengl/gl_backend.cc b/source/blender/gpu/opengl/gl_backend.cc
index 610fd5d980f..0ce01d80a77 100644
--- a/source/blender/gpu/opengl/gl_backend.cc
+++ b/source/blender/gpu/opengl/gl_backend.cc
@@ -419,6 +419,13 @@ static void detect_workarounds()
     GCaps.shader_storage_buffer_objects_support = false;
   }
 
+  /* Certain Intel based platforms don't clear the viewport textures. Always clearing leads to
+   * noticeable performance regressions. */
+  if (GPU_type_matches(
+          GPU_DEVICE_INTEL, static_cast<eGPUOSType>(GPU_OS_MAC | GPU_OS_UNIX), GPU_DRIVER_ANY)) {
+    GCaps.clear_viewport_workaround = true;
+  }
+
   /* Metal-related Workarounds. */
 
   /* Minimum Per-Vertex stride is 1 byte for OpenGL. */