Impossible to set precise dimensions to object when curve modifier is applied #51020

New Issue

John A. Paravantis · 2017-03-21T15:57:59+01:00

John A. Paravantis commented

2017-03-21 15:57:59 +01:00

CURVE MODIFIER PROBLEM X AXIS.blend

System Information
Windows 10 64 bit, NVidia GTX 950m

Blender Version
2.78c

Short description of error
Impossible to set precise dimensions to object when curve modifier is applied

Exact steps for others to reproduce the error
Attached file was created following the steps outlined below. You may jump to step (13) for the problem.

(1) Create a new blender file.

(2) Do not delete the default cube. From now on, it is best if you switch to the top ortho view and press Z to enable wireframe view.

(3) Click to enable the "Snap during transform" button (magnet icon), to make sure any transformations are snapped to the grid.

(4) Select and scale the default cube along the X axis (e.g. by pressing S, then X and then typing 10 followed by ENTER), so that it is extended to 20 Blender units along the X axis.

(5) Insert 9 cuts (edge loops) perpendicular to the X axis in the extended cube object, by selecting the cube, TABing into edit mode, pressing CTRL-R, X and then 9 and ENTER. This is done to allow it to be deformed later on. Exit edit more.

(6) Make sure the 3D cursor is at the origin of the cube object, by selecting the cube, pressing SHIFT-S, and choosing Cursor to selected.

(7) Add a path curve, which by default appears as a small straight line along the X axis.

(8) Select the path curve, and press S, X and then 5 followed by ENTER, to scale it 5 times along the X axis, so that it has the same length (20 Blender units) as the extended cube object.

(9) Make sure the 3D cursor is at the (0,0,0) origin point.

(10) Select the cube, press CTRL-SHIFT-ALT-C, and select Origin to 3D Cursor, to make sure the origin of the cube is at (0,0,0) point.

(11) Select the path curve, press CTRL-SHIFT-ALT-C and select Origin to 3D Cursor, to be sure that the origin of the path coincides with the origin of the cube object, which is at (0,0,0).

(12) Add a curve modifier to the cube, select the path curve as the object, and make sure that the X is set as the axis of transformation.

(13) If you now deform the path (as I have done in the blend-file), you will notice that the cube object (with its interim edge loops) deforms along the path as well, but its width (y-axis) becomes equal to the width of the deformed path object (9.345 in my blend-file), instead of remaining at 2 units.

If you set the width of the deformed cube object at 2 units, it looks better, but if you TAB into edit mode, you will see that the cube object has become very narrow (about 0.4 Blender units).

This behavior may be partially amended if "Display Modifier in Edit Mode" and "Adjust Edit Cage to Modifier Results" are turned on.

Nevertheless, it does not appear to be possible to maintain the cube at its original 2 units of width (Y-axis), while extending it along the curved path.

Another issue I have submitted, https:*developer.blender.org/T51022 , shows that such sizing/dimensioning programs are even more of a problem when a curve modifier is used after an array modifier.

[CURVE MODIFIER PROBLEM X AXIS.blend](https://archive.blender.org/developer/F546903/CURVE_MODIFIER_PROBLEM_X_AXIS.blend) **System Information** Windows 10 64 bit, NVidia GTX 950m **Blender Version** 2.78c **Short description of error** Impossible to set precise dimensions to object when curve modifier is applied **Exact steps for others to reproduce the error** Attached file was created following the steps outlined below. You may jump to step (13) for the problem. (1) Create a new blender file. (2) Do *not* delete the default cube. From now on, it is best if you switch to the top ortho view and press Z to enable wireframe view. (3) Click to enable the "Snap during transform" button (magnet icon), to make sure any transformations are snapped to the grid. (4) Select and scale the default cube along the X axis (e.g. by pressing S, then X and then typing 10 followed by ENTER), so that it is extended to 20 Blender units along the X axis. (5) Insert 9 cuts (edge loops) perpendicular to the X axis in the extended cube object, by selecting the cube, TABing into edit mode, pressing CTRL-R, X and then 9 and ENTER. This is done to allow it to be deformed later on. Exit edit more. (6) Make sure the 3D cursor is at the origin of the cube object, by selecting the cube, pressing SHIFT-S, and choosing Cursor to selected. (7) Add a path curve, which by default appears as a small straight line along the X axis. (8) Select the path curve, and press S, X and then 5 followed by ENTER, to scale it 5 times along the X axis, so that it has the same length (20 Blender units) as the extended cube object. (9) Make sure the 3D cursor is at the (0,0,0) origin point. (10) Select the cube, press CTRL-SHIFT-ALT-C, and select Origin to 3D Cursor, to make sure the origin of the cube is at (0,0,0) point. (11) Select the path curve, press CTRL-SHIFT-ALT-C and select Origin to 3D Cursor, to be sure that the origin of the path coincides with the origin of the cube object, which is at (0,0,0). (12) Add a curve modifier to the cube, select the path curve as the object, and make sure that the X is set as the axis of transformation. (13) If you now deform the path (as I have done in the blend-file), you will notice that the cube object (with its interim edge loops) deforms along the path as well, but its width (y-axis) becomes equal to the width of the deformed path object (9.345 in my blend-file), instead of remaining at 2 units. If you set the width of the deformed cube object at 2 units, it looks better, but if you TAB into edit mode, you will see that the cube object has become very narrow (about 0.4 Blender units). This behavior may be partially amended if "Display Modifier in Edit Mode" and "Adjust Edit Cage to Modifier Results" are turned on. Nevertheless, it does not appear to be possible to maintain the cube at its original 2 units of width (Y-axis), while extending it along the curved path. Another issue I have submitted, [https:*developer.blender.org/T51022 ](https:*developer.blender.org/T51022), shows that such sizing/dimensioning programs are even more of a problem when a curve modifier is used after an array modifier.

John A. Paravantis commented

2017-03-21 15:57:59 +01:00

Changed status to: 'Open'

John A. Paravantis commented

2017-03-21 15:57:59 +01:00

Added subscriber: @paravantis

Aaron Carlisle commented

2017-04-15 21:03:15 +02:00

Added subscriber: @Blendify

Aaron Carlisle commented

2017-04-15 21:03:15 +02:00

Please add a blend-file that shows the issue.

John A. Paravantis commented

2017-04-15 21:14:46 +02:00

Certainly.

Until I do, kindly also see https:*developer.blender.org/T51022 which is related and includes a blender file.

Certainly. Until I do, kindly also see [https:*developer.blender.org/T51022 ](https:*developer.blender.org/T51022) which is related and includes a blender file.

John A. Paravantis changed title from ~~Curve modifier appears to cause weird deformations~~ to Impossible to set precise dimensions to object when curve modifier is applied

2017-04-16 10:14:50 +02:00

John A. Paravantis commented

2017-04-16 10:20:47 +02:00

Blend-file added, description updated, as requested.

John A. Paravantis commented

2017-04-20 16:05:51 +02:00

Changed status from 'Open' to: 'Resolved'

John A. Paravantis closed this issue

2017-04-20 16:05:51 +02:00

John A. Paravantis self-assigned this 2017-04-20 16:05:51 +02:00

John A. Paravantis commented

2017-04-20 16:05:51 +02:00

I have resolved the issue via a post at Blender Stack Exchange: To make precise dimensioning possible, one has to change the radius of the control points of the curve from 14 to 1!

I have resolved the issue via a post at Blender Stack Exchange: To make precise dimensioning possible, one has to change the radius of the control points of the curve from 14 to 1!![RADIUS OF CONTROL POINTS OF CURVE.gif](https://archive.blender.org/developer/F557551/RADIUS_OF_CONTROL_POINTS_OF_CURVE.gif)

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Impossible to set precise dimensions to object when curve modifier is applied #51020