Fix/Workaround #34854: render buffer update writes to wrong layer

Was caused by recent change in image_buffer_rect_update which
was writing data to ibuf-rect_float. Apparently, this buffer
could point to different render layer than came from RenderResult.

Made quick fix for this, which ends up in skipping float buffer
update in image_buffer_rect_update and skipping GLSL when image
has both byte and float buffers.

This will bring speed down a bit, but slower blender is better
than broken blender.

Proper fix will arrive later this week.

2 files changed, 15 insertions, 16 deletions

diff --git a/source/blender/editors/render/render_internal.c b/source/blender/editors/render/render_internal.c
index de8accf0180..90c80cae1ad 100644
--- a/source/blender/editors/render/render_internal.c
+++ b/source/blender/editors/render/render_internal.c
@@ -140,23 +140,15 @@ void image_buffer_rect_update(Scene *scene, RenderResult *rr, ImBuf *ibuf, volat
 		}
 	}
 	if (rectf == NULL) return;
-	
-	rectf += 4 * (rr->rectx * ymin + xmin);
 
-	if (ibuf->rect) {
-		IMB_partial_display_buffer_update(ibuf, rectf, NULL, rr->rectx, rxmin, rymin,
-		                                  &scene->view_settings, &scene->display_settings,
-		                                  rxmin, rymin, rxmin + xmax, rymin + ymax, TRUE);
-	}
+	if (ibuf->rect == NULL)
+		imb_addrectImBuf(ibuf);
 
-	/* update float buffer as well, so fast GLSL display could use it
-	 *
-	 * TODO(sergey): not actually sure it is nice thing to modify something here
-	 *               but ibuf->rect used to be modified here
-	 */
-	IMB_buffer_float_from_float(ibuf->rect_float + 4 * (ibuf->x * rymin + rxmin), rectf,
-	                            4, IB_PROFILE_LINEAR_RGB, IB_PROFILE_LINEAR_RGB, FALSE,
-	                            xmax, ymax, ibuf->x, rr->rectx);
+	rectf += 4 * (rr->rectx * ymin + xmin);
+
+	IMB_partial_display_buffer_update(ibuf, rectf, NULL, rr->rectx, rxmin, rymin,
+	                                  &scene->view_settings, &scene->display_settings,
+	                                  rxmin, rymin, rxmin + xmax, rymin + ymax, TRUE);
 }
 
 /* ****************************** render invoking ***************** */
diff --git a/source/blender/editors/screen/glutil.c b/source/blender/editors/screen/glutil.c
index fecb3c58a2d..74086c7cc8b 100644
--- a/source/blender/editors/screen/glutil.c
+++ b/source/blender/editors/screen/glutil.c
@@ -998,7 +998,14 @@ void glaDrawImBuf_glsl_ctx(const bContext *C, ImBuf *ibuf, float x, float y, int
 	bool need_fallback = true;
 
 	/* Bytes and dithering are not supported on GLSL yet */
-	if (ibuf->rect_float && ibuf->dither == 0.0f) {
+
+	/* WORKAROUND: only use GLSL if there's no byte buffer at all,
+	 *             this is because of how render results are handled,
+	 *             they're not updating image buffer's float buffer,
+	 *             but writes data directly to it's byte buffer and
+	 *             modifies display buffer.
+	 */
+	if (ibuf->rect == NULL && ibuf->rect_float && ibuf->dither == 0.0f) {
 		if (IMB_colormanagement_setup_glsl_draw_from_ctx(C)) {
 			glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 			glColor4f(1.0, 1.0, 1.0, 1.0);