UVs offsets when using displace-modifier #67523

New Issue

Tobias Lijsen · 2019-07-23T15:51:09+02:00

Tobias Lijsen commented

2019-07-23 15:51:09 +02:00

System Information
Operating system: Windows-7-6.1.7601-SP1 64 Bits
Graphics card: GeForce GTX 970/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 416.34

Blender Version
Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-07-18 14:52, hash: 38d4483c6a
Worked: (optional)

Short description of error
grids UVs offsets when using displace-modifier - in UV-Editing everything looks fine

Exact steps for others to reproduce the error
add > mesh > grid
F9 > grids subdivisions > X=1000 Y=1000
N > Dimension X=1.0 Y=0.8
STRG+A > apply scale
new Modifier > add DISPLACE
Displace Mod > NEW Texture > and switch to Texture-Props
Open the Image Texture (see attached file)
Switch back to Modifier-Props
Displace-Mod > set Texture-Coordinates to UV

Tex-Coordinates are offset in X by Factor 0.5 - in UV-Editing everything looks fine - in 3D UVs are offset

**System Information** Operating system: Windows-7-6.1.7601-SP1 64 Bits Graphics card: GeForce GTX 970/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 416.34 **Blender Version** Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-07-18 14:52, hash: `38d4483c6a` Worked: (optional) **Short description of error** grids UVs offsets when using displace-modifier - in UV-Editing everything looks fine **Exact steps for others to reproduce the error** add > mesh > grid F9 > grids subdivisions > X=1000 Y=1000 N > Dimension X=1.0 Y=0.8 STRG+A > apply scale new Modifier > add DISPLACE Displace Mod > NEW Texture > and switch to Texture-Props Open the Image Texture (see attached file) Switch back to Modifier-Props Displace-Mod > set Texture-Coordinates to UV Tex-Coordinates are offset in X by Factor 0.5 - in UV-Editing everything looks fine - in 3D UVs are offset ![Schleife-2.tiff](https://archive.blender.org/developer/F7624795/Schleife-2.tiff)

Tobias Lijsen commented

2019-07-23 15:51:09 +02:00

Added subscriber: @blenderhilfe

William Reynish commented

2019-07-23 20:39:52 +02:00

Added subscriber: @WilliamReynish

William Reynish commented

2019-07-23 20:39:52 +02:00

I cannot reproduce this. Can you create a demo blend file that demonstrates this issue?

Tobias Lijsen commented

2019-07-25 14:55:44 +02:00

Okay, blend file attached.
Here u see the Error in Action, switch to EditMode and you see UVs are straight... mapping is messed up.

INFO: i got the error an all different machines...

UV_Problem1.blend

Okay, blend file attached. Here u see the Error in Action, switch to EditMode and you see UVs are straight... mapping is messed up. INFO: i got the error an all different machines... [UV_Problem1.blend](https://archive.blender.org/developer/F7628193/UV_Problem1.blend)

William Reynish commented

2019-07-25 18:28:50 +02:00

I don't understand how you created that object, since you have applied the modifiers.

When I unwrap it using UV > Unwrap from View (Bounds), it works normally. So how you got those wrong UV coords it's impossible to say.

I don't understand how you created that object, since you have applied the modifiers. When I unwrap it using UV > Unwrap from View (Bounds), it works normally. So how you got those wrong UV coords it's impossible to say.

Campbell Barton was assigned by William Reynish

2019-07-25 18:36:05 +02:00

William Reynish commented

2019-07-25 18:36:05 +02:00

Added subscriber: @ideasman42

William Reynish commented

2019-07-25 18:36:05 +02:00

Ah, I have now been able to reproduce this issue.

Turns out it has nothing at all to do with the displace modifier - the issue is that the Grid primitive's auto-generated UV's go bad if you have more than around 300 segments.

200 segments:

300 segments:

@ideasman42 assigned to you but feel free to re-assign. I assume it's a precision issue somewhere.

Ah, I have now been able to reproduce this issue. Turns out it has nothing at all to do with the displace modifier - the issue is that the Grid primitive's auto-generated UV's go bad if you have more than around 300 segments. 200 segments: ![Screenshot 2019-07-25 at 18.32.56.png](https://archive.blender.org/developer/F7628406/Screenshot_2019-07-25_at_18.32.56.png) 300 segments: ![Screenshot 2019-07-25 at 18.33.14.png](https://archive.blender.org/developer/F7628408/Screenshot_2019-07-25_at_18.33.14.png) @ideasman42 assigned to you but feel free to re-assign. I assume it's a precision issue somewhere.

matc commented

2019-07-26 08:52:31 +02:00

Added subscriber: @matc

matc commented

2019-07-26 08:52:31 +02:00

The smallest one I could find is 13 by 3.

bpy.ops.mesh.primitive_grid_add(x_subdivisions=13, y_subdivisions=3, enter_editmode=False)

The smallest one I could find is 13 by 3. `bpy.ops.mesh.primitive_grid_add(x_subdivisions=13, y_subdivisions=3, enter_editmode=False)` ![13x3.png](https://archive.blender.org/developer/F7629235/13x3.png)

matc commented

2019-07-27 06:27:39 +02:00

This should solve the problem. An alternative would be to introduce a counter.

diff --git a/source/blender/bmesh/operators/bmo_primitive.c b/source/blender/bmesh/operators/bmo_primitive.c
index cf3d6b8bf56..bea437d63d0 100644
--- a/source/blender/bmesh/operators/bmo_primitive.c
+++ b/source/blender/bmesh/operators/bmo_primitive.c
@@ -807,6 +807,7 @@ void BM_mesh_calc_uvs_grid(BMesh *bm,

   const float dx = 1.0f / (float)(x_segments - 1);
   const float dy = 1.0f / (float)(y_segments - 1);
+  const float dx_half = dx / 2.0f;
   float x = 0.0f;
   float y = dy;

@@ -844,7 +845,7 @@ void BM_mesh_calc_uvs_grid(BMesh *bm,
     }

     x += dx;
-    if (x >= 1.0f) {
+    if (x + dx_half >= 1.0) {
       x = 0.0f;
       y += dy;
     }

This should solve the problem. An alternative would be to introduce a counter. ``` diff --git a/source/blender/bmesh/operators/bmo_primitive.c b/source/blender/bmesh/operators/bmo_primitive.c index cf3d6b8bf56..bea437d63d0 100644 --- a/source/blender/bmesh/operators/bmo_primitive.c +++ b/source/blender/bmesh/operators/bmo_primitive.c @@ -807,6 +807,7 @@ void BM_mesh_calc_uvs_grid(BMesh *bm, const float dx = 1.0f / (float)(x_segments - 1); const float dy = 1.0f / (float)(y_segments - 1); + const float dx_half = dx / 2.0f; float x = 0.0f; float y = dy; @@ -844,7 +845,7 @@ void BM_mesh_calc_uvs_grid(BMesh *bm, } x += dx; - if (x >= 1.0f) { + if (x + dx_half >= 1.0) { x = 0.0f; y += dy; } ```

blender-admin commented

2019-07-29 06:26:39 +02:00

This issue was referenced by a542f50b51

This issue was referenced by a542f50b51af0167acc55d4cf2b06490a704ce93

Campbell Barton commented

2019-07-29 06:29:10 +02:00

Changed status from 'Open' to: 'Resolved'

Campbell Barton closed this issue

2019-07-29 06:29:10 +02:00

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UVs offsets when using displace-modifier #67523