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Loop Cut Crash
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System Information
Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: AMD Radeon R9 200 Series ATI Technologies Inc. 4.5.13559 Core Profile Context 26.20.12001.11014

Blender Version
Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-07-11 13:50, hash: rB06312c6d2db8
Worked: (optional)

Short description of error
When I make a Loop Cut and make the number somewhere between 16 cuts and play fast with the smoothness it crashes.

Exact steps for others to reproduce the error
First, go to edit mode, from the UI select Loop Cut and cut the cube. Set the Number of Cuts around 16 or more and play with the Smoothness fast. It doesn't crash every time but most of the times. If it doesn't crash in the first attempt add more Loop Cuts on the other sides and again add number of cuts and play with the smoothness fast by increasing and decreasing the value

Event Timeline

If you increase the Number of Cuts, there is a bigger chance of crashing

on OpenSUSE TW linux 'loopcut smoothness work fine, i had play with it for one minute as fast possible and no crash.

re test with 325 loopcuts, still work fine

Please check if your hardware meet Blender requirement at or upload your System-Info file generated from /Help/Save System Info' item, Thank you

I remind you that the Terascale chipset is not supported by Blender 2.80 and newer versions

Sebastian Parborg (zeddb) lowered the priority of this task from 90 to 30.Jul 17 2019, 4:21 PM

System Information
Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: GeForce GTX 960/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 431.36

Blender Version
version: 2.80 (sub 74), branch: master, commit date: 2019-07-11 13:50, hash: rB06312c6d2db8

Tested with up to 100 cuts, no problems. Couldn't get it to crash and my system kind of crashes easily.

I can repro, I think, but it took a long time of playing around to hit it -- So sadly I don't have a better simplified set of steps but I do have a stack:

The following happens on a full debug build from a BLI_assert inside BM_mesh_elem_table_ensure ... the incoming BMesh looks completely broken.

Exception thrown: read access violation.
blender.exe!BLI_mempool_len(BLI_mempool * pool) Line 456	C
blender.exe!bmiter__elem_of_mesh_begin(BMIter__elem_of_mesh * iter) Line 425	C
blender.exe!BM_iter_init(BMIter * iter, BMesh * bm, const unsigned char itype, void * data) Line 154	C
blender.exe!BM_iter_new(BMIter * iter, BMesh * bm, const unsigned char itype, void * data) Line 168	C
blender.exe!BM_mesh_elem_table_check(BMesh * bm) Line 1932	C
blender.exe!BM_mesh_elem_table_ensure(BMesh * bm, const unsigned char htype) Line 1963	C
blender.exe!DRW_draw_select_id_object(Scene * scene, RegionView3D * rv3d, Object * ob, short select_mode, bool draw_facedot, unsigned int initial_offset, unsigned int * r_vert_offset, unsigned int * r_edge_offset, unsigned int * r_face_offset) Line 2765	C
blender.exe!ed_select_id_draw_bases(EDSelectID_Context * sel_id_ctx, ViewContext * vc, short select_mode) Line 189	C
blender.exe!ED_view3d_select_id_context_create(ViewContext * vc, Base * * bases, const unsigned int bases_len, short select_mode) Line 242	C
blender.exe!EDBM_edge_find_nearest_ex(ViewContext * vc, float * r_dist, float * r_dist_center, const bool use_select_bias, bool use_cycle, BMEdge * * r_eed_zbuf, Base * * bases, unsigned int bases_len, unsigned int * r_base_index) Line 567	C
blender.exe!gizmo_preselect_edgering_test_select(bContext * C, wmGizmo * gz, const int * mval) Line 308	C
blender.exe!gizmo_find_intersected_3d(bContext * C, const int * co, wmGizmo * * visible_gizmos, const int visible_gizmos_len, int * r_part) Line 642	C
blender.exe!wm_gizmomap_highlight_find(wmGizmoMap * gzmap, bContext * C, const wmEvent * event, int * r_part) Line 754	C
blender.exe!wm_handlers_do_intern(bContext * C, wmEvent * event, ListBase * handlers) Line 2793	C
blender.exe!wm_handlers_do(bContext * C, wmEvent * event, ListBase * handlers) Line 2945	C
blender.exe!wm_event_do_handlers(bContext * C) Line 3397	C
blender.exe!WM_main(bContext * C) Line 420	C
blender.exe!main(int argc, const unsigned char * * UNUSED_argv_c) Line 502	C

@Roger B (rboxman) so it crashes when you play with the smoothness parameter in the redo panel or what?

Yeah, I seem to hit it when I scrub the smoothness value back and forth and that usually triggers the above after some time. I sometimes have to stop the scrub and play with the cut # too and then go back to smoothness scrubbing (and repeat) for it to hit.

Sebastian Parborg (zeddb) raised the priority of this task from 30 to 80.Jul 23 2019, 2:32 PM

@Ray molenkamp (LazyDodo) can you reproduce this? ASAN doesn't complain and I can't reproduce this it seems.

Richard Antalik (ISS) changed the task status from Needs Information from Developers to Needs Information from User.Jan 3 2020, 4:18 AM

@Roger B (rboxman) Can you please retry this with latest build?

I don't know how for how long (approximately) I am supposed to test this.

Richard Antalik (ISS) closed this task as Archived.Jan 13 2020, 9:09 AM
Richard Antalik (ISS) claimed this task.

Since last asking for information it has been 7 or more days, due to the policy of our bug tracker we will have to close the report.