Draw Manager: OpenGL render support

Works for clay-engine but doesn't draw objects with eevee.

2 files changed, 41 insertions, 0 deletions

diff --git a/source/blender/draw/DRW_engine.h b/source/blender/draw/DRW_engine.h
index 6b3aee73229..8811309bcc1 100644
--- a/source/blender/draw/DRW_engine.h
+++ b/source/blender/draw/DRW_engine.h
@@ -41,6 +41,7 @@ struct ViewContext;
 struct ViewportEngineData;
 struct View3D;
 struct rcti;
+struct GPUOffScreen;
 
 #include "BLI_sys_types.h"  /* for bool */
 
@@ -67,6 +68,10 @@ void DRW_draw_view(const struct bContext *C);
 void DRW_draw_render_loop(
         struct Depsgraph *graph,
         struct View3D *v3d, struct ARegion *ar);
+void DRW_draw_render_loop_offscreen(
+        struct Depsgraph *graph,
+        struct View3D *v3d, struct ARegion *ar,
+        struct GPUOffScreen *ofs);
 void DRW_draw_select_loop(
         struct Depsgraph *graph,
         struct View3D *v3d, struct ARegion *ar,
diff --git a/source/blender/draw/intern/draw_manager.c b/source/blender/draw/intern/draw_manager.c
index f116ecbc8b4..07182ef2774 100644
--- a/source/blender/draw/intern/draw_manager.c
+++ b/source/blender/draw/intern/draw_manager.c
@@ -2188,6 +2188,11 @@ void DRW_draw_view(const bContext *C)
 	DRW_draw_render_loop(graph, v3d, ar);
 }
 
+/**
+ * Used for both regular drawing and off-screen drawing.
+ *
+ * \param ofs: When not NULL, use this data to create the viewport.
+ */
 void DRW_draw_render_loop(
         struct Depsgraph *graph,
         View3D *v3d, ARegion *ar)
@@ -2273,6 +2278,37 @@ void DRW_draw_render_loop(
 	memset(&DST, 0x0, sizeof(DST));
 }
 
+void DRW_draw_render_loop_offscreen(
+        struct Depsgraph *graph,
+        View3D *v3d, ARegion *ar, GPUOffScreen *ofs)
+{
+	RegionView3D *rv3d = ar->regiondata;
+
+	/* backup */
+	void *backup_viewport = rv3d->viewport;
+	{
+		/* backup (_never_ use rv3d->viewport) */
+		rv3d->viewport = GPU_viewport_create_from_offscreen(ofs);
+	}
+
+	DST.draw_ctx.evil_C = NULL;
+
+	DRW_draw_render_loop(graph, v3d, ar);
+
+	/* restore */
+	{
+		/* don't free data owned by 'ofs' */
+		GPU_viewport_clear_from_offscreen(rv3d->viewport);
+		GPU_viewport_free(rv3d->viewport);
+		MEM_freeN(rv3d->viewport);
+
+		rv3d->viewport = backup_viewport;
+	}
+
+	/* we need to re-bind (annoying!) */
+	GPU_offscreen_bind(ofs, false);
+}
+
 /**
  * object mode select-loop, see: ED_view3d_draw_select_loop (legacy drawing).
  */