Python API: option to use OpenGL context in RenderEngine.render

When bl_use_gpu_context is set, an OpenGL context will be available for
OpenGL based render engines.

Differential Revision: https://developer.blender.org/D8305

source/blender/draw/DRW_engine.h

@@ -43,6 +43,7 @@ struct GPUViewport;
 struct ID;
 struct Main;
 struct Object;
+struct Render;
 struct RenderEngine;
 struct RenderEngineType;
 struct Scene;
@@ -137,6 +138,9 @@ void DRW_render_gpencil(struct RenderEngine *engine, struct Depsgraph *depsgraph
 struct DRWInstanceDataList *DRW_instance_data_list_create(void);
 void DRW_instance_data_list_free(struct DRWInstanceDataList *idatalist);
 
+void DRW_render_context_enable(struct Render *render);
+void DRW_render_context_disable(struct Render *render);
+
 void DRW_opengl_context_create(void);
 void DRW_opengl_context_destroy(void);
 void DRW_opengl_context_enable(void);

source/blender/draw/engines/eevee/eevee_engine.c

@@ -601,7 +601,7 @@ RenderEngineType DRW_engine_viewport_eevee_type = {
     NULL,
     EEVEE_ENGINE,
     N_("Eevee"),
-    RE_INTERNAL | RE_USE_PREVIEW | RE_USE_STEREO_VIEWPORT,
+    RE_INTERNAL | RE_USE_PREVIEW | RE_USE_STEREO_VIEWPORT | RE_USE_GPU_CONTEXT,
     NULL,
     &DRW_render_to_image,
     NULL,

source/blender/draw/engines/select/select_engine.c

@@ -378,7 +378,7 @@ RenderEngineType DRW_engine_viewport_select_type = {
     NULL,
     SELECT_ENGINE,
     N_("Select ID"),
-    RE_INTERNAL | RE_USE_STEREO_VIEWPORT,
+    RE_INTERNAL | RE_USE_STEREO_VIEWPORT | RE_USE_GPU_CONTEXT,
     NULL,
     NULL,
     NULL,

source/blender/draw/engines/workbench/workbench_engine.c

@@ -641,7 +641,7 @@ RenderEngineType DRW_engine_viewport_workbench_type = {
     NULL,
     WORKBENCH_ENGINE,
     N_("Workbench"),
-    RE_INTERNAL | RE_USE_STEREO_VIEWPORT,
+    RE_INTERNAL | RE_USE_STEREO_VIEWPORT | RE_USE_GPU_CONTEXT,
     NULL,
     &DRW_render_to_image,
     NULL,

source/blender/draw/intern/draw_manager.c

@@ -1660,24 +1660,8 @@ void DRW_render_gpencil(struct RenderEngine *engine, struct Depsgraph *depsgraph
   RenderEngineType *engine_type = engine->type;
   RenderData *r = &scene->r;
   Render *render = engine->re;
-  /* Changing Context */
-  if (G.background && DST.gl_context == NULL) {
-    WM_init_opengl(G_MAIN);
-  }
 
-  void *re_gl_context = RE_gl_context_get(render);
-  void *re_gpu_context = NULL;
-
-  /* Changing Context */
-  if (re_gl_context != NULL) {
-    DRW_opengl_render_context_enable(re_gl_context);
-    /* We need to query gpu context after a gl context has been bound. */
-    re_gpu_context = RE_gpu_context_get(render);
-    DRW_gpu_render_context_enable(re_gpu_context);
-  }
-  else {
-    DRW_opengl_context_enable();
-  }
+  DRW_render_context_enable(render);
 
   /* Reset before using it. */
   drw_state_prepare_clean_for_draw(&DST);
@@ -1729,14 +1713,7 @@ void DRW_render_gpencil(struct RenderEngine *engine, struct Depsgraph *depsgraph
   /* Restore Drawing area. */
   GPU_framebuffer_restore();
 
-  /* Changing Context */
-  if (re_gl_context != NULL) {
-    DRW_gpu_render_context_disable(re_gpu_context);
-    DRW_opengl_render_context_disable(re_gl_context);
-  }
-  else {
-    DRW_opengl_context_disable();
-  }
+  DRW_render_context_disable(render);
 
   DST.buffer_finish_called = false;
 }
@@ -1749,24 +1726,6 @@ void DRW_render_to_image(RenderEngine *engine, struct Depsgraph *depsgraph)
   DrawEngineType *draw_engine_type = engine_type->draw_engine;
   Render *render = engine->re;
 
-  if (G.background && DST.gl_context == NULL) {
-    WM_init_opengl(G_MAIN);
-  }
-
-  void *re_gl_context = RE_gl_context_get(render);
-  void *re_gpu_context = NULL;
-
-  /* Changing Context */
-  if (re_gl_context != NULL) {
-    DRW_opengl_render_context_enable(re_gl_context);
-    /* We need to query gpu context after a gl context has been bound. */
-    re_gpu_context = RE_gpu_context_get(render);
-    DRW_gpu_render_context_enable(re_gpu_context);
-  }
-  else {
-    DRW_opengl_context_enable();
-  }
-
   /* IMPORTANT: We don't support immediate mode in render mode!
    * This shall remain in effect until immediate mode supports
    * multiple threads. */
@@ -1842,15 +1801,6 @@ void DRW_render_to_image(RenderEngine *engine, struct Depsgraph *depsgraph)
 
   /* Reset state after drawing */
   DRW_state_reset();
-
-  /* Changing Context */
-  if (re_gl_context != NULL) {
-    DRW_gpu_render_context_disable(re_gpu_context);
-    DRW_opengl_render_context_disable(re_gl_context);
-  }
-  else {
-    DRW_opengl_context_disable();
-  }
 }
 
 void DRW_render_object_iter(
@@ -2763,6 +2713,42 @@ void DRW_engines_free(void)
   DRW_opengl_context_disable();
 }
 
+void DRW_render_context_enable(Render *render)
+{
+  if (G.background && DST.gl_context == NULL) {
+    WM_init_opengl(G_MAIN);
+  }
+
+  void *re_gl_context = RE_gl_context_get(render);
+
+  /* Changing Context */
+  if (re_gl_context != NULL) {
+    DRW_opengl_render_context_enable(re_gl_context);
+    /* We need to query gpu context after a gl context has been bound. */
+    void *re_gpu_context = NULL;
+    re_gpu_context = RE_gpu_context_get(render);
+    DRW_gpu_render_context_enable(re_gpu_context);
+  }
+  else {
+    DRW_opengl_context_enable();
+  }
+}
+
+void DRW_render_context_disable(Render *render)
+{
+  void *re_gl_context = RE_gl_context_get(render);
+
+  if (re_gl_context != NULL) {
+    void *re_gpu_context = NULL;
+    re_gpu_context = RE_gpu_context_get(render);
+    DRW_gpu_render_context_disable(re_gpu_context);
+    DRW_opengl_render_context_disable(re_gl_context);
+  }
+  else {
+    DRW_opengl_context_disable();
+  }
+}
+
 /** \} */
 
 /** \name Init/Exit (DRW_opengl_ctx)
@@ -2903,8 +2889,8 @@ void DRW_gpu_render_context_disable(void *UNUSED(re_gpu_context))
  * switch to it just to submit the final frame, which has notable performance impact.
  *
  * We could "inject" a context through DRW_opengl_render_context_enable(), but that would have to
- * work from the main thread, which is tricky to get working too. The preferable solution would be
- * using a separate thread for VR drawing where a single context can stay active. */
+ * work from the main thread, which is tricky to get working too. The preferable solution would
+ * be using a separate thread for VR drawing where a single context can stay active. */
 void *DRW_xr_opengl_context_get(void)
 {
   return DST.gl_context;

source/blender/editors/gpencil/gpencil_convert.c

@@ -400,7 +400,7 @@ static void gpencil_stroke_path_animation_preprocess_gaps(tGpTimingData *gtd,
 static void gpencil_stroke_path_animation_add_keyframes(ReportList *reports,
                                                         PointerRNA ptr,
                                                         PropertyRNA *prop,
-                                                   Depsgraph *depsgraph,
+                                                        Depsgraph *depsgraph,
                                                         FCurve *fcu,
                                                         Curve *cu,
                                                         tGpTimingData *gtd,

source/blender/makesrna/intern/rna_render.c

@@ -845,6 +845,14 @@ static void rna_def_render_engine(BlenderRNA *brna)
   RNA_def_property_ui_text(
       prop, "Use Eevee Viewport", "Uses Eevee for viewport shading in LookDev shading mode");
 
+  prop = RNA_def_property(srna, "bl_use_gpu_context", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(prop, NULL, "type->flag", RE_USE_GPU_CONTEXT);
+  RNA_def_property_flag(prop, PROP_REGISTER_OPTIONAL);
+  RNA_def_property_ui_text(
+      prop,
+      "Use GPU Context",
+      "Enable OpenGL context for the render method, for engines that render using OpenGL");
+
   prop = RNA_def_property(srna, "bl_use_shading_nodes_custom", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "type->flag", RE_USE_SHADING_NODES_CUSTOM);
   RNA_def_property_boolean_default(prop, true);

source/blender/render/extern/include/RE_engine.h

@@ -60,6 +60,7 @@ struct bNodeTree;
 #define RE_USE_SHADING_NODES_CUSTOM 64
 #define RE_USE_SPHERICAL_STEREO 128
 #define RE_USE_STEREO_VIEWPORT 256
+#define RE_USE_GPU_CONTEXT 512
 
 /* RenderEngine.flag */
 #define RE_ENGINE_ANIMATION 1

source/blender/render/intern/source/external_engine.c

@@ -863,8 +863,16 @@ int RE_engine_render(Render *re, int do_all)
         re->draw_lock(re->dlh, 0);
       }
 
+      if (engine->type->flag & RE_USE_GPU_CONTEXT) {
+        DRW_render_context_enable(engine->re);
+      }
+
       type->render(engine, engine->depsgraph);
 
+      if (engine->type->flag & RE_USE_GPU_CONTEXT) {
+        DRW_render_context_disable(engine->re);
+      }
+
       /* Grease pencil render over previous render result.
        *
        * NOTE: External engine might have been requested to free its