Applying Transformations Causes "Hollow Looking" Models #52049

New Issue

Ricky Bobby · 2017-07-13T22:55:54+02:00

Ricky Bobby commented

2017-07-13 22:55:54 +02:00

System Information
Windows 10, no graphics card (CPU based graphics)

Blender Version
2.77

Short description of error
As seen in the video, applying scale to the model turns it into, well... the glitchiest thing I have ever seen.

Exact steps for others to reproduce the error
from glitch.blend (attached), simply apply the scale and watch as the model commits suicide.

The normals definitely flipped, but the question is why.
glitch.blend

2017-07-09-2151-40.mp4

**System Information** Windows 10, no graphics card (CPU based graphics) **Blender Version** 2.77 **Short description of error** As seen in the video, applying scale to the model turns it into, well... the glitchiest thing I have ever seen. **Exact steps for others to reproduce the error** from glitch.blend (attached), simply apply the scale and watch as the model commits suicide. The normals definitely flipped, but the question is why. [glitch.blend](https://archive.blender.org/developer/F666338/glitch.blend) [2017-07-09-2151-40.mp4](https://archive.blender.org/developer/F666339/2017-07-09-2151-40.mp4)

Ricky Bobby commented

2017-07-13 22:55:54 +02:00

Changed status to: 'Open'

Ricky Bobby commented

2017-07-13 22:55:54 +02:00

Added subscriber: @rickybobby

Germano Cavalcante commented

2017-07-14 04:03:44 +02:00

Added subscribers: @ideasman42, @mano-wii

Germano Cavalcante commented

2017-07-14 04:03:45 +02:00

This is because the object is on negative scale, that is, the object is flipped.

One solution would be to flip the normals in edit mode.
But since this is not the expected behavior. Maybe it's better to edit the code.

@ideasman42, can you take a look? Here is a possible solution:

diff --git a/source/blender/editors/object/object_transform.c b/source/blender/editors/object/object_transform.c
index 4d7d7df0d2f..879e2817222 100644
--- a/source/blender/editors/object/object_transform.c
+++ b/source/blender/editors/object/object_transform.c
@@ -525,6 +525,9 @@ static int apply_objects_internal(bContext *C, ReportList *reports, bool apply_l
 				multiresModifier_scale_disp(scene, ob);
 			
 			/* adjust data */
+			if (ob->transflag & OB_NEG_SCALE) {
+				BKE_mesh_polygons_flip(me->mpoly, me->mloop, &me->ldata, me->totpoly);
+			}
 			BKE_mesh_transform(me, mat, true);
 			
 			/* update normals */

This is because the object is on negative scale, that is, the object is flipped. One solution would be to flip the normals in edit mode. But since this is not the expected behavior. Maybe it's better to edit the code. @ideasman42, can you take a look? Here is a possible solution: ``` diff --git a/source/blender/editors/object/object_transform.c b/source/blender/editors/object/object_transform.c index 4d7d7df0d2f..879e2817222 100644 --- a/source/blender/editors/object/object_transform.c +++ b/source/blender/editors/object/object_transform.c @@ -525,6 +525,9 @@ static int apply_objects_internal(bContext *C, ReportList *reports, bool apply_l multiresModifier_scale_disp(scene, ob); /* adjust data */ + if (ob->transflag & OB_NEG_SCALE) { + BKE_mesh_polygons_flip(me->mpoly, me->mloop, &me->ldata, me->totpoly); + } BKE_mesh_transform(me, mat, true); /* update normals */ ```

Paul Szajner commented

2017-07-16 04:29:26 +02:00

Added subscriber: @sozap

Paul Szajner commented

2017-07-16 04:29:26 +02:00

It makes things weirdier in your video because of the Shading/backface culling option turned on...
Then after apply scale what you see is only the inside of the model.

This is appending from a long time in blender, could be great to see it fixed one day, on the other hand we can live with it, tho it can be disturbing for newcomers...

It makes things weirdier in your video because of the Shading/backface culling option turned on... Then after apply scale what you see is only the inside of the model. This is appending from a long time in blender, could be great to see it fixed one day, on the other hand we can live with it, tho it can be disturbing for newcomers...

Bastien Montagne commented

2017-07-19 10:57:58 +02:00

Added subscriber: @mont29

Bastien Montagne commented

2017-07-19 10:57:58 +02:00

Changed status from 'Open' to: 'Archived'

Bastien Montagne closed this issue

2017-07-19 10:57:58 +02:00

Bastien Montagne self-assigned this 2017-07-19 10:57:58 +02:00

Bastien Montagne commented

2017-07-19 10:57:58 +02:00

Yeah, thanks for the report, but do not see any bug here, it is indeed expected that when you scale negatively, you get “inside out” mesh (that actually face winding, i.e. order in which face corners “turn around” face center, that get reversed, and imply reversed normals).

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Applying Transformations Causes "Hollow Looking" Models #52049