Dyntopo + Snake tool produce weird artifacts after grab tool #65523

New Issue

Michael Soluyanov · 2019-06-05T13:05:25+02:00

Michael Soluyanov commented

2019-06-05 13:05:25 +02:00

System Information
Operating system: Linux-4.15.0-47-generic-x86_64-with-debian-buster-sid 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 390.116

Blender Version
Broken: version: 2.80 (sub 74), branch: blender2.7, commit date: 2019-06-04 22:32, hash: e80cbdac33
Worked: not found

2019-06-05 13-54-21.mp4

Short description of error
Dyntopo + Snake tool produce weird artifacts after grab tool

Exact steps for others to reproduce the error

Open sculpting UI setup.
Enable dyntopo.
move some geometry with grab tool.
Set big brush size then use snake tool.
Some weird artifacts will be shown. Like part of original mesh stay in original location.
Press Ctrl+Z - artifacts will disappear.

**System Information** Operating system: Linux-4.15.0-47-generic-x86_64-with-debian-buster-sid 64 Bits Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 390.116 **Blender Version** Broken: version: 2.80 (sub 74), branch: blender2.7, commit date: 2019-06-04 22:32, hash: `e80cbdac33` Worked: not found [2019-06-05 13-54-21.mp4](https://archive.blender.org/developer/F7088201/2019-06-05_13-54-21.mp4) **Short description of error** Dyntopo + Snake tool produce weird artifacts after grab tool **Exact steps for others to reproduce the error** 1. Open sculpting UI setup. 2. Enable dyntopo. 3. move some geometry with grab tool. 4. Set big brush size then use snake tool. 5. Some weird artifacts will be shown. Like part of original mesh stay in original location. ![Снимок экрана от 2019-06-05 14-04-15.png](https://archive.blender.org/developer/F7088203/Снимок_экрана_от_2019-06-05_14-04-15.png) 6. Press Ctrl+Z - artifacts will disappear.

Michael Soluyanov commented

2019-06-05 13:05:25 +02:00

Added subscriber: @crantisz

Stanislav Ovcharov commented

2019-06-05 15:19:22 +02:00

Added subscriber: @StanislavOvcharov

tom k commented

2019-06-05 23:12:40 +02:00

Added subscriber: @tomjk

tom k commented

2019-06-05 23:12:40 +02:00

Can duplicate (Linux Mint 18.3, NVIDIA GeForce GTX 750 Ti, today's official build e80cbdac33)

Does not require to grab or perform any other operation before snake hook.

Edit: Does not actually require snake hook at all, I think any tool that will collapse geometry will do it.

Artifacts also disappear if you enter another mode (object, edit etc.)

Screencast 2019-06-05 22:03:02.webm

Can duplicate (Linux Mint 18.3, NVIDIA GeForce GTX 750 Ti, today's official build e80cbdac331a) Does not require to grab or perform any other operation before snake hook. Edit: Does not actually require snake hook at all, I think any tool that will collapse geometry will do it. Artifacts also disappear if you enter another mode (object, edit etc.) [Screencast 2019-06-05 22:03:02.webm](https://archive.blender.org/developer/F7088783/Screencast_2019-06-05_22_03_02.webm)

tom k commented

2019-06-05 23:37:24 +02:00

Probably duplicate of #58920.

Germano Cavalcante commented

2019-06-06 03:57:46 +02:00

Added subscribers: @Psy-Fi, @mano-wii

Germano Cavalcante commented

2019-06-06 03:57:47 +02:00

The problem is that within the BVH node, the drawing buffer (ie the batch) and the mesh lose their synchrony when the resulting amount of triangles is 0.
What happens is that while the mesh in the BVH node gets 0 vertices, the batch is untouched.

Something similar happened before and was solved by @Psy-Fi here: e60b18d51d
In this solution vert_buff and index_buff were deleted.

But another solution was found in 52af5fa31f
There vert_buff and index_buff were untouched but their drawing was ignored.

Here an adaptation of the first solution:

diff --git a/source/blender/gpu/intern/gpu_buffers.c b/source/blender/gpu/intern/gpu_buffers.c
index e30fccbf29d..a232327e1d3 100644
--- a/source/blender/gpu/intern/gpu_buffers.c
+++ b/source/blender/gpu/intern/gpu_buffers.c
@@ -827,6 +827,11 @@ void GPU_pbvh_bmesh_buffers_update(GPU_PBVH_Buffers *buffers,
   }
 
   if (!tottri) {
+    GPU_BATCH_DISCARD_SAFE(buffers->triangles);
+    GPU_BATCH_DISCARD_SAFE(buffers->lines);
+    GPU_INDEXBUF_DISCARD_SAFE(buffers->index_lines_buf);
+    GPU_INDEXBUF_DISCARD_SAFE(buffers->index_buf);
+    GPU_VERTBUF_DISCARD_SAFE(buffers->vert_buf);
     buffers->tot_tri = 0;
     return;
   }

An adaptation of the second solution would be to check the buffers->tottri in sculpt_draw_cb.

The problem is that within the BVH node, the drawing buffer (ie the batch) and the mesh lose their synchrony when the resulting amount of triangles is 0. What happens is that while the mesh in the BVH node gets 0 vertices, the batch is untouched. Something similar happened before and was solved by @Psy-Fi here: e60b18d51d In this solution `vert_buff` and `index_buff` were deleted. But another solution was found in 52af5fa31f There `vert_buff` and `index_buff` were untouched but their drawing was ignored. Here an adaptation of the first solution: ``` diff --git a/source/blender/gpu/intern/gpu_buffers.c b/source/blender/gpu/intern/gpu_buffers.c index e30fccbf29d..a232327e1d3 100644 --- a/source/blender/gpu/intern/gpu_buffers.c +++ b/source/blender/gpu/intern/gpu_buffers.c @@ -827,6 +827,11 @@ void GPU_pbvh_bmesh_buffers_update(GPU_PBVH_Buffers *buffers, } if (!tottri) { + GPU_BATCH_DISCARD_SAFE(buffers->triangles); + GPU_BATCH_DISCARD_SAFE(buffers->lines); + GPU_INDEXBUF_DISCARD_SAFE(buffers->index_lines_buf); + GPU_INDEXBUF_DISCARD_SAFE(buffers->index_buf); + GPU_VERTBUF_DISCARD_SAFE(buffers->vert_buf); buffers->tot_tri = 0; return; } ``` An adaptation of the second solution would be to check the `buffers->tottri` in `sculpt_draw_cb`.

Brecht Van Lommel commented

2019-06-06 06:22:05 +02:00

Closed as duplicate of #58920

Brecht Van Lommel closed this issue

2019-06-06 06:22:05 +02:00

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Dyntopo + Snake tool produce weird artifacts after grab tool #65523