Creating custom orientation fails in seemingly random situations #77243

New Issue

Jesse Yurkovich · 2020-06-01T01:02:51+02:00

Jesse Yurkovich commented

2020-06-01 01:02:51 +02:00

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1070 with Max-Q Design/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 441.66

Blender Version
Broken: version: 2.90.0 Alpha, branch: master, commit date: 2020-05-29 18:08, hash: 2ee94c954d
Broken: version: 2.83 latest
Broken: version: 2.82 a release
Worked: 2.79 (sub 7), branch: blender2.7, commit date: 2019-06-27 10:41, hash: e045fe53f1b0

Short description of error
Creating a custom orientation seems to be hit or miss. It often fails in situations where it probably should not, probably due to some degenerate matrix condition or otherwise.

Exact steps for others to reproduce the error
bad-custom-orientation.blend

Open the attached .blend
The faces are already selected : the -X and the +Z faces of the default cube
Try to create a custom orientation
Experience failure -- Unable to create orientation
Select the +X and +Z faces instead
Try to create a custom orientation now
Success
Other combinations of 2 faces for the default cube will also fail. 2.79 seems to be better at succeeding here in general (the only 2-face combination that fails in 2.79 is the -Z and +Z case)

**System Information** Operating system: Windows-10-10.0.18362-SP0 64 Bits Graphics card: GeForce GTX 1070 with Max-Q Design/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 441.66 **Blender Version** Broken: version: 2.90.0 Alpha, branch: master, commit date: 2020-05-29 18:08, hash: `2ee94c954d` Broken: version: 2.83 latest Broken: version: 2.82 a release Worked: 2.79 (sub 7), branch: blender2.7, commit date: 2019-06-27 10:41, hash: e045fe53f1b0 **Short description of error** Creating a custom orientation seems to be hit or miss. It often fails in situations where it probably should not, probably due to some degenerate matrix condition or otherwise. **Exact steps for others to reproduce the error** [bad-custom-orientation.blend](https://archive.blender.org/developer/F8568681/bad-custom-orientation.blend) - Open the attached .blend - The faces are already selected : the -X and the +Z faces of the default cube - Try to create a custom orientation - Experience failure -- `Unable to create orientation` - Select the +X and +Z faces instead - Try to create a custom orientation now - Success - Other combinations of 2 faces for the default cube will also fail. 2.79 seems to be better at succeeding here in general (the only 2-face combination that fails in 2.79 is the -Z and +Z case)

Jesse Yurkovich commented

2020-06-01 01:02:51 +02:00

Added subscriber: @deadpin

Germano Cavalcante commented

2020-06-03 15:27:37 +02:00

Added subscribers: @ideasman42, @mano-wii

Germano Cavalcante commented

2020-06-03 15:27:37 +02:00

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

Germano Cavalcante commented

2020-06-03 15:27:37 +02:00

This is complex.
In the case shown in the file, the sum of the tangents points in the same direction as the sum of the normals. So it can't get a reliable matrix.

The code is very old. I wonder if the tangent calculation can be a little more predictable.
This involves the bmesh code, so @ideasman42, if you want to take a look beforehand, here's a possible fix:

diff --git a/source/blender/editors/transform/transform_orientations.c b/source/blender/editors/transform/transform_orientations.c
index cd170b144d8..6e81ce13bb7 100644
--- a/source/blender/editors/transform/transform_orientations.c
+++ b/source/blender/editors/transform/transform_orientations.c
@@ -740,11 +740,32 @@ int getTransformOrientation_ex(const bContext *C,
           BMFace *efa;
           BMIter iter;
 
+          /* Sum of normals. */
           BM_ITER_MESH (efa, &iter, em->bm, BM_FACES_OF_MESH) {
             if (BM_elem_flag_test(efa, BM_ELEM_SELECT)) {
-              BM_face_calc_tangent_auto(efa, vec);
               add_v3_v3(normal, efa->no);
-              add_v3_v3(plane, vec);
+            }
+          }
+
+          /* Suggest a direction to coordinate the sum of tangents. */
+          float ortho_up_axis[3];
+          project_plane_v3_v3v3(ortho_up_axis, (float[3]){0.0f, 0.0f, 1.0f}, normal);
+          if (ortho_up_axis[2] == 0.0f) {
+            /* Normal points to Z axis. Use Y axis. */
+            ortho_up_axis[1] = 1.0f;
+          }
+
+          /* Sum of tangents. */
+          BM_ITER_MESH (efa, &iter, em->bm, BM_FACES_OF_MESH) {
+            if (BM_elem_flag_test(efa, BM_ELEM_SELECT)) {
+              BM_face_calc_tangent_auto(efa, vec);
+              /* Add the tangents that come closest to a specific direction. */
+              if (dot_v3v3(ortho_up_axis, vec) >= 0.0f) {
+                add_v3_v3(plane, vec);
+              }
+              else {
+                sub_v3_v3(plane, vec);
+              }
             }
           }

This is complex. In the case shown in the file, the sum of the tangents points in the same direction as the sum of the normals. So it can't get a reliable matrix. The code is very old. I wonder if the tangent calculation can be a little more predictable. This involves the bmesh code, so @ideasman42, if you want to take a look beforehand, here's a possible fix: ``` diff --git a/source/blender/editors/transform/transform_orientations.c b/source/blender/editors/transform/transform_orientations.c index cd170b144d8..6e81ce13bb7 100644 --- a/source/blender/editors/transform/transform_orientations.c +++ b/source/blender/editors/transform/transform_orientations.c @@ -740,11 +740,32 @@ int getTransformOrientation_ex(const bContext *C, BMFace *efa; BMIter iter; + /* Sum of normals. */ BM_ITER_MESH (efa, &iter, em->bm, BM_FACES_OF_MESH) { if (BM_elem_flag_test(efa, BM_ELEM_SELECT)) { - BM_face_calc_tangent_auto(efa, vec); add_v3_v3(normal, efa->no); - add_v3_v3(plane, vec); + } + } + + /* Suggest a direction to coordinate the sum of tangents. */ + float ortho_up_axis[3]; + project_plane_v3_v3v3(ortho_up_axis, (float[3]){0.0f, 0.0f, 1.0f}, normal); + if (ortho_up_axis[2] == 0.0f) { + /* Normal points to Z axis. Use Y axis. */ + ortho_up_axis[1] = 1.0f; + } + + /* Sum of tangents. */ + BM_ITER_MESH (efa, &iter, em->bm, BM_FACES_OF_MESH) { + if (BM_elem_flag_test(efa, BM_ELEM_SELECT)) { + BM_face_calc_tangent_auto(efa, vec); + /* Add the tangents that come closest to a specific direction. */ + if (dot_v3v3(ortho_up_axis, vec) >= 0.0f) { + add_v3_v3(plane, vec); + } + else { + sub_v3_v3(plane, vec); + } } } ```

Philipp Oeser removed the

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Creating custom orientation fails in seemingly random situations #77243