Grease Pencil GPF error if stroke thickness change too much between stroke points #49614

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Antonio Vazquez · 2016-10-09T19:12:19+02:00

Antonio Vazquez commented

2016-10-09 19:12:19 +02:00

Windows 10 64 bits
Blender 2.80 Branch Hash: e636529
GTX 660

If a stroke is set as volumetric and the size of the point change in size, a GPF error appears after uncheck Volumetric. Really, the error is not related to volumetric but how the stroke is drawn if the thickness change too much.

I have run some debug and the error appears here in drawgpencil.c:

if (fabsf(pt->pressure - curpressure) > 0.2f / (float)thickness) {
     immEnd();

It looks the immEnd() is not available in the midle of the operation. I'm not an OpenGl expert and I have no idea how to fix it, so I need help. Maybe, we can avoid this "mid" immEnd call.

One way to reproduce:

Open file Test_Volumetric_280.blend
Uncheck Volumetric Strokes in palette color panel.

Windows 10 64 bits Blender 2.80 Branch Hash: e636529 GTX 660 If a stroke is set as volumetric and the size of the point change in size, a GPF error appears after uncheck Volumetric. Really, the error is not related to volumetric but how the stroke is drawn if the thickness change too much. I have run some debug and the error appears here in drawgpencil.c: ``` if (fabsf(pt->pressure - curpressure) > 0.2f / (float)thickness) { immEnd(); ``` It looks the immEnd() is not available in the midle of the operation. I'm not an OpenGl expert and I have no idea how to fix it, so I need help. Maybe, we can avoid this "mid" immEnd call. One way to reproduce: 1) Open file [Test_Volumetric_280.blend](https://archive.blender.org/developer/F376041/Test_Volumetric_280.blend) 2) Uncheck Volumetric Strokes in palette color panel.

Antonio Vazquez commented

2016-10-09 19:12:19 +02:00

Changed status to: 'Open'

Antonio Vazquez commented

2016-10-09 19:12:19 +02:00

Added subscriber: @antoniov

Mike Erwin commented

2016-10-09 19:30:32 +02:00

Added subscriber: @MikeErwin

Mike Erwin commented

2016-10-09 19:30:32 +02:00

With your file I hit the same problem on Mac.
Debugging now...

With your file I hit the same problem on Mac. Debugging now...

Antonio Vazquez commented

2016-10-09 19:32:41 +02:00

@MikeErwin I have seen the problem is there is only one point, but the type is GL_LINE_STRIP

assert(imm.vertex_idx == 0 || vertex_count_makes_sense_for_primitive(imm.vertex_idx, imm.primitive));

The second part of the assert is True

@MikeErwin I have seen the problem is there is only one point, but the type is GL_LINE_STRIP ``` assert(imm.vertex_idx == 0 || vertex_count_makes_sense_for_primitive(imm.vertex_idx, imm.primitive)); ``` The second part of the assert is True

Mike Erwin self-assigned this 2016-10-09 21:34:44 +02:00

Mike Erwin commented

2016-10-09 21:34:44 +02:00

We talked more about this on IRC. I will adjust the gpencil drawing logic to fix this.

Antonio Vazquez commented

2016-10-14 13:15:26 +02:00

@MikeErwin I have been fixing the bug and there were more problems for cyclic strokes and colors. I have fixed with this code in my PC and I would like you confirm is ok before apply the commit. I have to do the same with buffer_stroke draw.

I know this will change in the future and it's a temporary solution, but at least we can test other Grease Pencil areas without a GPF.

PS: I load here an image of the change because I don't know how attach a diff file to the task.

@MikeErwin I have been fixing the bug and there were more problems for cyclic strokes and colors. I have fixed with this code in my PC and I would like you confirm is ok before apply the commit. I have to do the same with buffer_stroke draw. I know this will change in the future and it's a temporary solution, but at least we can test other Grease Pencil areas without a GPF. ![BugFix.png](https://archive.blender.org/developer/F378276/BugFix.png) PS: I load here an image of the change because I don't know how attach a diff file to the task.

Mike Erwin commented

2016-10-14 18:21:47 +02:00

Looks good to me!