Incorrect position of bezier point handle when set via Python #40978

New Issue

Miro Horváth · 2014-07-07T13:37:39+02:00

Miro Horváth commented

2014-07-07 13:37:39 +02:00

Blender Version
2.71

Running the code below I expect to get curve as on the left picture, but I'm getting the result from right picture. No matter what coordinates I set to "p2.handle_left" I always get same numbers for X,Y(7.91548 in case of the code below) and Z is always 0 even if I use coords like 4,1,100.

import bpy

curve = bpy.data.curves.new("TEST",'CURVE')

spline = curve.splines.new('BEZIER')
p1 = spline.bezier_points[0]

p1.co = 0,0,0  
p1.handle_left_type = "ALIGNED"
p1.handle_right_type = "ALIGNED"
p1.handle_right = 4,1,0

spline.bezier_points.add()
p2 = spline.bezier_points[1]
p2.co = 5,5,0
p2.handle_left_type = "ALIGNED"
p2.handle_right_type = "ALIGNED"
p2.handle_left = 4,1,0

object = bpy.data.objects.new("TEST", curve)
bpy.context.scene.objects.link(object)

Blender Version 2.71 Running the code below I expect to get curve as on the left picture, but I'm getting the result from right picture. No matter what coordinates I set to "p2.handle_left" I always get same numbers for X,Y(7.91548 in case of the code below) and Z is always 0 even if I use coords like 4,1,100. ![handles.jpg](https://archive.blender.org/developer/F96958/handles.jpg) ``` import bpy curve = bpy.data.curves.new("TEST",'CURVE') spline = curve.splines.new('BEZIER') p1 = spline.bezier_points[0] p1.co = 0,0,0 p1.handle_left_type = "ALIGNED" p1.handle_right_type = "ALIGNED" p1.handle_right = 4,1,0 spline.bezier_points.add() p2 = spline.bezier_points[1] p2.co = 5,5,0 p2.handle_left_type = "ALIGNED" p2.handle_right_type = "ALIGNED" p2.handle_left = 4,1,0 object = bpy.data.objects.new("TEST", curve) bpy.context.scene.objects.link(object) ```

Miro Horváth commented

2014-07-07 13:37:39 +02:00

Changed status to: 'Open'

Miro Horváth commented

2014-07-07 13:37:39 +02:00

Added subscriber: @MiroHorvath

Joshua Leung commented

2014-07-07 13:47:38 +02:00

Added subscriber: @JoshuaLeung

Joshua Leung commented

2014-07-07 13:47:38 +02:00

When investigating a bug for the keyframes ui, I came across a similar problem. The bug is basically rooted in limitations in the handle recalculation code (calchandleNurb_intern()), specifically, in how it handles aligned handles recalculation.The problem is that when you've got both handles selected, it can't really figure out what to do, so it either treats it as only the first (left) handle being selected, or it gives up entirely. The workaround the keyframes UI uses now is that when editing the second handle, we ensure that only the second handle is selected when we set the value.

When investigating a bug for the keyframes ui, I came across a similar problem. The bug is basically rooted in limitations in the handle recalculation code (calchandleNurb_intern()), specifically, in how it handles aligned handles recalculation.The problem is that when you've got both handles selected, it can't really figure out what to do, so it either treats it as *only* the first (left) handle being selected, or it gives up entirely. The workaround the keyframes UI uses now is that when editing the second handle, we ensure that only the second handle is selected when we set the value.

Bastien Montagne commented

2014-07-07 14:16:55 +02:00

Changed status from 'Open' to: 'Archived'

Bastien Montagne closed this issue

2014-07-07 14:16:55 +02:00

Bastien Montagne self-assigned this 2014-07-07 14:16:55 +02:00

Bastien Montagne commented

2014-07-07 14:16:55 +02:00

In other words, this will work:

import bpy

curve = bpy.data.curves.new("TEST",'CURVE')

spline = curve.splines.new('BEZIER')
p1 = spline.bezier_points[0]

p1.co = 0,0,0
p1.handle_left_type = "ALIGNED"
p1.handle_right_type = "ALIGNED"
p1.handle_right = 4,1,0

spline.bezier_points.add()
p2 = spline.bezier_points[1]
p2.co = 5,5,0
p2.handle_left_type = "ALIGNED"
p2.handle_right_type = "ALIGNED"
p2.select_right_handle = False
p2.select_left_handle = True
p2.handle_left = 4,1,0

object = bpy.data.objects.new("TEST", curve)
bpy.context.scene.objects.link(object)

This is not really a bug, more like an internal limitation, closing.

In other words, this will work: ``` import bpy ``` ``` curve = bpy.data.curves.new("TEST",'CURVE') ``` ``` spline = curve.splines.new('BEZIER') p1 = spline.bezier_points[0] ``` ``` p1.co = 0,0,0 p1.handle_left_type = "ALIGNED" p1.handle_right_type = "ALIGNED" p1.handle_right = 4,1,0 ``` ``` spline.bezier_points.add() p2 = spline.bezier_points[1] p2.co = 5,5,0 p2.handle_left_type = "ALIGNED" p2.handle_right_type = "ALIGNED" p2.select_right_handle = False p2.select_left_handle = True p2.handle_left = 4,1,0 ``` ``` object = bpy.data.objects.new("TEST", curve) bpy.context.scene.objects.link(object) ``` This is not really a bug, more like an internal limitation, closing.

Miro Horváth commented

2014-07-07 14:23:14 +02:00

Thnx for the quick reply aligorith,

yup you're right adding p2.select_left_handle = True really does the trick.

Cheers

Thnx for the quick reply aligorith, yup you're right adding p2.select_left_handle = True really does the trick. Cheers

Lukas Tönne commented

2014-07-07 15:02:08 +02:00

Added subscriber: @LukasTonne

Lukas Tönne commented

2014-07-07 15:02:08 +02:00

Ok, @JoshuaLeung's explanation is totally correct. However, in a case like this the calculation order should be nicely resolvable, because only one of the handle sides is set at a time, i.e. the other side would be expected to follow it. This additional ordering information gets lost because everything uses the same generic function ...

Lukas Tönne commented

2014-07-07 15:04:43 +02:00

Added subscriber: @mont29

Lukas Tönne commented

2014-07-07 15:04:43 +02:00

Oops, @mont29 answered in the meantime: This solution is doing just that, only that it requires modifying selection to force the calculation order. This should not actually be necessary, but could be integrated into the rna call.

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Incorrect position of bezier point handle when set via Python #40978