Hooray! Finally found the dreaded "Opengl crash" the poor orange team

suffered for the entire movie. :)

It only happened when rendering large frames, using a lot of memory and
typically when you also use other software in meantime.

Reason: the main thread does the drawing updating, while rendering is
still continuing. When using Ztransp, there was a free buffer done
when possibly a draw could still be in progress. Only crashed when drawing
is slow... explaining why it only showed up in more complex cases.

3 files changed, 19 insertions, 11 deletions

diff --git a/source/blender/render/extern/include/RE_pipeline.h b/source/blender/render/extern/include/RE_pipeline.h
index 8a5fb7ec63c..eed13e15ed5 100644
--- a/source/blender/render/extern/include/RE_pipeline.h
+++ b/source/blender/render/extern/include/RE_pipeline.h
@@ -72,7 +72,8 @@ typedef struct RenderLayer {
 	unsigned int lay;			
 	int layflag, passflag;		
 	
-	float *rectf;	/* 4 float, standard rgba buffer */
+	float *rectf;		/* 4 float, standard rgba buffer */
+	float *acolrect;	/* 4 float, optional transparent buffer, needs storage for display updates */
 	
 	ListBase passes;
 	
diff --git a/source/blender/render/intern/source/pipeline.c b/source/blender/render/intern/source/pipeline.c
index 5de50c2f8c0..1cac8b2cbcf 100644
--- a/source/blender/render/intern/source/pipeline.c
+++ b/source/blender/render/intern/source/pipeline.c
@@ -158,6 +158,9 @@ static void free_render_result(RenderResult *res)
 		RenderLayer *rl= res->layers.first;
 		
 		if(rl->rectf) MEM_freeT(rl->rectf);
+		/* acolrect is optionally allocated in shade_tile, only free here since it can be used for drawing */
+		if(rl->acolrect) MEM_freeT(rl->acolrect);
+		
 		while(rl->passes.first) {
 			RenderPass *rpass= rl->passes.first;
 			if(rpass->rect) MEM_freeT(rpass->rect);
diff --git a/source/blender/render/intern/source/rendercore.c b/source/blender/render/intern/source/rendercore.c
index b9300241468..2adf589392b 100644
--- a/source/blender/render/intern/source/rendercore.c
+++ b/source/blender/render/intern/source/rendercore.c
@@ -3197,23 +3197,25 @@ void zbufshadeDA_tile(RenderPart *pa)
 		/* transp layer */
 		if(R.flag & R_ZTRA) {
 			if(rl->layflag & SCE_LAY_ZTRA) {
-				float *acolrect= MEM_callocT(4*sizeof(float)*pa->rectx*pa->recty, "alpha layer");
-				float *fcol= rl->rectf, *acol= acolrect;
+				float *fcol, *acol;
 				int x;
 				
+				/* allocate, but not free here, for asynchronous display of this rect in main thread */
+				rl->acolrect= MEM_callocT(4*sizeof(float)*pa->rectx*pa->recty, "alpha layer");
+				
 				if(rl->passflag & SCE_PASS_VECTOR)
 					if(rl->layflag & SCE_LAY_SOLID)
 						reset_sky_speedvectors(pa, rl);
 				
 				/* swap for live updates */
-				SWAP(float *, acolrect, rl->rectf);
+				SWAP(float *, rl->acolrect, rl->rectf);
 				zbuffer_transp_shade(pa, rl, rl->rectf);
-				SWAP(float *, acolrect, rl->rectf);
+				SWAP(float *, rl->acolrect, rl->rectf);
 				
+				fcol= rl->rectf; acol= rl->acolrect;
 				for(x=pa->rectx*pa->recty; x>0; x--, acol+=4, fcol+=4) {
 					addAlphaOverFloat(fcol, acol);
 				}
-				MEM_freeT(acolrect);
 			}
 		}
 		
@@ -3329,23 +3331,25 @@ void zbufshade_tile(RenderPart *pa)
 		
 		if(R.flag & R_ZTRA) {
 			if(rl->layflag & SCE_LAY_ZTRA) {
-				float *acolrect= MEM_callocT(4*sizeof(float)*pa->rectx*pa->recty, "alpha layer");
-				float *fcol= rl->rectf, *acol= acolrect;
+				float *fcol, *acol;
 				int x;
 				
+				/* allocate, but not free here, for asynchronous display of this rect in main thread */
+				rl->acolrect= MEM_callocT(4*sizeof(float)*pa->rectx*pa->recty, "alpha layer");
+				
 				if(addpassflag & SCE_PASS_VECTOR)
 					if(rl->layflag & SCE_LAY_SOLID)
 						reset_sky_speedvectors(pa, rl);
 				
 				/* swap for live updates */
-				SWAP(float *, acolrect, rl->rectf);
+				SWAP(float *, rl->acolrect, rl->rectf);
 				zbuffer_transp_shade(pa, rl, rl->rectf);
-				SWAP(float *, acolrect, rl->rectf);
+				SWAP(float *, rl->acolrect, rl->rectf);
 				
+				fcol= rl->rectf; acol= rl->acolrect;
 				for(x=pa->rectx*pa->recty; x>0; x--, acol+=4, fcol+=4) {
 					addAlphaOverFloat(fcol, acol);
 				}
-				MEM_freeT(acolrect);
 			}
 		}