object raycast only returns the original face index for evaluated meshes of objects with mirror modifiers #86766

New Issue

MACHIN3 · 2021-03-20T18:36:59+01:00

MACHIN3 commented

2021-03-20 18:36:59 +01:00

System Information
Operating system: Linux-4.15.0-136-generic-x86_64-with-debian-buster-sid 64 Bits
Graphics card: GeForce GTX 1050/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.39

Blender Version
Broken: version: 2.92.0, branch: master, commit date: 2021-02-24 16:25, hash: 02948a2cab
Worked: -

Short description of error
If you have and object with mirror modifiers and obj.raycast on them, the returned face index will be wrong, especially on the mirrored side. If the modifier uses bisect, the face index will be wrong on the original side as well.
I'm only aware of the mirror modifier doings this. For instance, I have boolean modifiers on the object in the sample scene, creating faces only present in the evaluated mesh, and those indices are returned correctly.

edit: The weld mod (if at the end of the stack) seems to be affected as well. Can report separately if necessary.

My current workaround is creating the evaluated meshes manually via bpy.data.meshes.new_from_object(obj.evaluated_get(dg), depsgraph=dg) and a BVH raycast, but that's not always practical, and I would really prefer doing this on the fly using obj.ray_cast(origin, direction, depsgraph=dg)

The supplied blend file, uses the "operator_modal_view3d_raycast.py" template with minimal modification.
obj_raycast_mirror_mod_evaluated_mesh_face_index.blend

demonstration:
https://www.youtube.com/watch?v=crbCdO6mItM

Exact steps for others to reproduce the error

open the blend file
run the script in the text editor
run the Raycast op from the search menu
click on various faces and compare the raycast results in the terminal to the text objects on the faces, indicating the correct indices on the evaluated mesh

**System Information** Operating system: Linux-4.15.0-136-generic-x86_64-with-debian-buster-sid 64 Bits Graphics card: GeForce GTX 1050/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.39 **Blender Version** Broken: version: 2.92.0, branch: master, commit date: 2021-02-24 16:25, hash: `02948a2cab` Worked: - **Short description of error** If you have and object with mirror modifiers and `obj.raycast` on them, the returned face index will be wrong, especially on the mirrored side. If the modifier uses bisect, the face index will be wrong on the original side as well. I'm only aware of the mirror modifier doings this. For instance, I have boolean modifiers on the object in the sample scene, creating faces only present in the evaluated mesh, and those indices are returned correctly. **edit:** The weld mod (if at the end of the stack) seems to be affected as well. Can report separately if necessary. My current workaround is creating the evaluated meshes manually via `bpy.data.meshes.new_from_object(obj.evaluated_get(dg), depsgraph=dg)` and a BVH raycast, but that's not always practical, and I would really prefer doing this on the fly using `obj.ray_cast(origin, direction, depsgraph=dg)` The supplied blend file, uses the "operator_modal_view3d_raycast.py" template with minimal modification. [obj_raycast_mirror_mod_evaluated_mesh_face_index.blend](https://archive.blender.org/developer/F9901137/obj_raycast_mirror_mod_evaluated_mesh_face_index.blend) demonstration: https://www.youtube.com/watch?v=crbCdO6mItM **Exact steps for others to reproduce the error** * open the blend file * run the script in the text editor * run the Raycast op from the search menu * click on various faces and compare the raycast results in the terminal to the text objects on the faces, indicating the correct indices on the evaluated mesh

MACHIN3 commented

2021-03-20 18:37:00 +01:00

Added subscriber: @MACHIN3

Falk David commented

2021-03-22 13:34:17 +01:00

Added subscriber: @filedescriptor

Falk David commented

2021-03-22 13:34:17 +01:00

Changed status from 'Needs Triage' to: 'Confirmed'

Falk David commented

2021-03-22 13:34:17 +01:00

I can confirm this issue on the latest 2.93.0 Alpha, branch: master, commit date: 2021-03-22 11:23, hash: c4c195672d.

I can confirm this issue on the latest 2.93.0 Alpha, branch: master, commit date: 2021-03-22 11:23, hash: `c4c195672d`.

Campbell Barton commented

2021-04-22 10:20:00 +02:00

Added subscriber: @ideasman42

Campbell Barton commented

2021-04-22 10:20:00 +02:00

Currently the original index is looked up, we could optionally support returning the final index.
See: rna_Object_ray_cast

Setting as TODO.

Currently the original index is looked up, we could optionally support returning the final index. See: `rna_Object_ray_cast` Setting as TODO.

Campbell Barton changed title from ~~object raycast returns wrong face index for evaluated meshes of objects with mirror modifiers~~ to object raycast only returns the original face index for evaluated meshes of objects with mirror modifiers

2021-04-22 10:20:21 +02:00

MACHIN3 commented

2021-04-22 18:24:43 +02:00

Returning the final index is what I would expect yes. It already does return the final distance, location and normal. For boolean mods it also already returns the final index too, hence why I was caught off guard, when getting these results for mirror(and potentially other?) mods.

Current workarounds to get the final index are inefficient.

Returning the final index is what I would expect yes. It already does return the final distance, location and normal. For boolean mods it also already returns the final index too, hence why I was caught off guard, when getting these results for mirror(and potentially other?) mods. Current workarounds to get the final index are inefficient.

MACHIN3 commented

2021-06-11 15:55:03 +02:00

FWIW, scene.ray_cast does not have these issues either.

Philipp Oeser removed the

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object raycast only returns the original face index for evaluated meshes of objects with mirror modifiers #86766