Fix T77564: VSE (and compositor background) lost stereoscopy preview

Issue introduced on fe045b2b77dc6d7f0b552619fe824b496d34db6c.

Since the stereoscopy compositing (anaglyph, ...) is only done for
viewports the VSE preview and compositor need to use viewports.

Reviewed by: dfelinto

Differential Revision: https://developer.blender.org/D8472

1 files changed, 11 insertions, 1 deletions

diff --git a/source/blender/editors/space_sequencer/sequencer_draw.c b/source/blender/editors/space_sequencer/sequencer_draw.c
index 0f4690c11d5..b784104e9ce 100644
--- a/source/blender/editors/space_sequencer/sequencer_draw.c
+++ b/source/blender/editors/space_sequencer/sequencer_draw.c
@@ -56,6 +56,7 @@
 #include "GPU_matrix.h"
 #include "GPU_state.h"
 #include "GPU_vertex_buffer.h"
+#include "GPU_viewport.h"
 
 #include "ED_anim_api.h"
 #include "ED_gpencil.h"
@@ -1537,7 +1538,7 @@ static void sequencer_preview_clear(void)
   float col[3];
 
   UI_GetThemeColor3fv(TH_SEQ_PREVIEW, col);
-  GPU_clear_color(col[0], col[1], col[2], 0.0);
+  GPU_clear_color(col[0], col[1], col[2], 1.0f);
   GPU_clear(GPU_COLOR_BIT);
 }
 
@@ -1780,6 +1781,12 @@ void sequencer_draw_preview(const bContext *C,
     return;
   }
 
+  /* Setup offscreen buffers. */
+  GPUViewport *viewport = WM_draw_region_get_viewport(region);
+
+  GPUFrameBuffer *framebuffer_overlay = GPU_viewport_framebuffer_overlay_get(viewport);
+  GPU_framebuffer_bind_no_srgb(framebuffer_overlay);
+
   /* Setup view. */
   sequencer_display_size(scene, viewrect);
   UI_view2d_totRect_set(v2d, viewrect[0] + 0.5f, viewrect[1] + 0.5f);
@@ -1798,6 +1805,9 @@ void sequencer_draw_preview(const bContext *C,
   ibuf = sequencer_ibuf_get(
       bmain, depsgraph, scene, sseq, cfra, frame_ofs, names[sseq->multiview_eye]);
 
+  /* sequencer_ibuf_get can call GPU_framebuffer_bind. So disable srgb framebuffer again. */
+  GPU_framebuffer_bind_no_srgb(framebuffer_overlay);
+
   if (ibuf) {
     scope = sequencer_get_scope(scene, sseq, ibuf, draw_backdrop);