WM: new offscreen window draw method to replace all existing methods.

For Blender 2.8 we had to be compatible with very old OpenGL versions, and
triple buffer was designed to work without offscreen rendering, by copying
the the backbuffer to a texture right before swapping. This way we could
avoid redrawing unchanged regions by copying them from this texture on the
next redraws. Triple buffer used to suffer from poor performance and driver
bugs on specific cards, so alternative draw methods remained available.

Now that we require newer OpenGL, we can have just a single draw method
that draw each region into an offscreen buffer, and then draws those to
the screen. This has some advantages:

* Poor 3D view performance when using Region Overlap should be solved now,
  since we can also cache overlapping regions in offscreen buffers.
* Page flip, anaglyph and interlace stereo drawing can be a little faster
  by avoiding a copy to an intermediate texture.
* The new 3D view drawing already writes to an offscreen buffer, which we
  can draw from directly instead of duplicating it to another buffer.
* Eventually we will be able to remove depth and stencil buffers from the
  window and save memory, though at the moment there are still some tools
  using it so it's not possible yet.
* This also fixes a bug with Eevee sampling not progressing with stereo
  drawing in the 3D viewport.

Differential Revision: https://developer.blender.org/D3061

1 files changed, 6 insertions, 1 deletions

diff --git a/source/blender/windowmanager/wm.h b/source/blender/windowmanager/wm.h
index b2e8c914fa8..073adef177c 100644
--- a/source/blender/windowmanager/wm.h
+++ b/source/blender/windowmanager/wm.h
@@ -31,6 +31,7 @@
 #ifndef __WM_H__
 #define __WM_H__
 
+struct ARegion;
 struct wmWindow;
 struct ReportList;
 
@@ -82,7 +83,11 @@ void wm_autosave_read(bContext *C, struct ReportList *reports);
 void wm_autosave_location(char *filepath);
 
 /* wm_stereo.c */
-void wm_method_draw_stereo3d(const bContext *C, wmWindow *win);
+void wm_stereo3d_draw_interlace(wmWindow *win, struct ARegion *ar);
+void wm_stereo3d_draw_anaglyph(wmWindow *win, struct ARegion *ar);
+void wm_stereo3d_draw_sidebyside(wmWindow *win, int view);
+void wm_stereo3d_draw_topbottom(wmWindow *win, int view);
+
 void wm_stereo3d_mouse_offset_apply(wmWindow *win, int *r_mouse_xy);
 int wm_stereo3d_set_exec(bContext *C, wmOperator *op);
 int wm_stereo3d_set_invoke(bContext *C, wmOperator *op, const wmEvent *event);