bge KX_GameObject.localPosition affect KX_GameObject.worldPosition instead #44847

New Issue

Olm-e · 2015-05-26T11:27:33+02:00

Olm-e commented

2015-05-26 11:27:33 +02:00

System Information
Operating system and graphics card
any (tested on lenovo R400 with Intel and on AMD 4core with Nvidia GTX460

Blender Version
Broken: 2.73, 2.74 and 2.75 testbuild1

Short description of error

when setting Object.localPosition, it sets Object.worldPosition instead

https://www.blender.org/api/blender_python_api_2_62_release/bge.types.html#bge.types.KX_GameObject.localPosition

Exact steps for others to reproduce the error
Based on a (as simple as possible) attached .blend file with minimum amount of steps

attached .blend demonstrate that trying to steer the default cube on local Orientation based on a localPosition speed doesn't work, the movement is linear and the cube is rotating on itself instead of turning following a curve ... localPosition-bug.blend

**System Information** Operating system and graphics card any (tested on lenovo R400 with Intel and on AMD 4core with Nvidia GTX460 **Blender Version** Broken: 2.73, 2.74 and 2.75 testbuild1 **Short description of error** when setting Object.localPosition, it sets Object.worldPosition instead https://www.blender.org/api/blender_python_api_2_62_release/bge.types.html#bge.types.KX_GameObject.localPosition **Exact steps for others to reproduce the error** Based on a (as simple as possible) attached .blend file with minimum amount of steps attached .blend demonstrate that trying to steer the default cube on local Orientation based on a localPosition speed doesn't work, the movement is linear and the cube is rotating on itself instead of turning following a curve ... [localPosition-bug.blend](https://archive.blender.org/developer/F180114/localPosition-bug.blend)

Olm-e commented

2015-05-26 11:27:33 +02:00

Changed status to: 'Open'

Olm-e commented

2015-05-26 11:27:33 +02:00

Added subscriber: @Olm-e-9

Sergey Sharybin commented

2015-05-26 11:47:21 +02:00

Added subscriber: @Sergey

Jorge Bernal commented

2015-05-29 10:20:43 +02:00

Added subscriber: @JorgeBernalMartinez

Jorge Bernal self-assigned this 2015-05-29 10:20:43 +02:00

Jorge Bernal commented

2015-05-29 10:20:43 +02:00

I confirm the bug.

Jorge Bernal commented

2015-05-29 20:15:43 +02:00

Changed status from 'Open' to: 'Archived'

Jorge Bernal closed this issue

2015-05-29 20:15:43 +02:00

Jorge Bernal commented

2015-05-29 20:15:43 +02:00

I was mistaked. This is not a bug.

localPosition is the object's position relative to its parent and is the same as worldPosition when there is no parent. If you want to move the object along its local axes, create a movement vector, rotate it by the object orientation matrix, then add it to the objects position.

You can replace

obj.localPosition[1] = obj.localPosition[1] + speed

by

obj.applyMovement((0,speed,0),True)

Thanks for reporting

I was mistaked. This is not a bug. localPosition is the object's position relative to its parent and is the same as worldPosition when there is no parent. If you want to move the object along its local axes, create a movement vector, rotate it by the object orientation matrix, then add it to the objects position. You can replace ``` obj.localPosition[1] = obj.localPosition[1] + speed ``` by ``` obj.applyMovement((0,speed,0),True) ``` Thanks for reporting

Olm-e commented

2015-05-29 20:42:21 +02:00

Changed status from 'Archived' to: 'Open'

Olm-e reopened this issue

2015-05-29 20:42:21 +02:00

Olm-e commented

2015-05-29 20:42:21 +02:00

Well ...
1 : I I know multiple manner to do the same effect, it's not the point, but thanks, this add another,
2 : so either it must be renamed "relativeParentPosition" or it has to be added with emphasis in the blender documentation, because it is not coherent with the internal blender usage where you have local and world axis that have nothing to do with parenting... and then it still lacks a function localPosition coherent with the blender interface :
if you play with local axis in the blender interface you would have the described behaviour, not the one you describe.
and it is not coherent with basic physics principles of relativity, and so confusing both with interface and intuitive understanding...

in conclusion : to me it is a bug, somewhere, and not a wrong assumption of my part: spending one day to understand what the behaviour of that function is, and having yourself confirming the bug in the first place is well the proof that there is one. Please give better arguments if you have on the contrary,

tks

Well ... 1 : I I know multiple manner to do the same effect, it's not the point, but thanks, this add another, 2 : so either it must be renamed "relativeParentPosition" or it has to be added with emphasis in the blender documentation, because it is not coherent with the internal blender usage where you have local and world axis that have nothing to do with parenting... and then it still lacks a function localPosition coherent with the blender interface : if you play with local axis in the blender interface you would have the described behaviour, not the one you describe. and it is not coherent with basic physics principles of relativity, and so confusing both with interface and intuitive understanding... in conclusion : to me it is a bug, somewhere, and not a wrong assumption of my part: spending one day to understand what the behaviour of that function is, and having yourself confirming the bug in the first place is well the proof that there is one. Please give better arguments if you have on the contrary, tks

Jorge Bernal commented

2015-05-30 12:17:19 +02:00

Changed status from 'Open' to: 'Archived'

Jorge Bernal closed this issue

2015-05-30 12:17:19 +02:00

Jorge Bernal commented

2015-05-30 12:17:19 +02:00

well, my confirmation was done quickly between 2 day-job tasks. But I'm with you that the bge api documentation has to be improved.
I add this request as my particular TODO for the modifications that I want to do for this part of bge api (among others like reference or .copy(), etc).

Apart from this, I close the report as it is not a bug (localPosition works as intended).

Thanks for taking your time reporting.

well, my confirmation was done quickly between 2 day-job tasks. But I'm with you that the bge api documentation has to be improved. I add this request as my particular TODO for the modifications that I want to do for this part of bge api (among others like reference or .copy(), etc). Apart from this, I close the report as it is not a bug (localPosition works as intended). Thanks for taking your time reporting.

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bge KX_GameObject.localPosition affect KX_GameObject.worldPosition instead #44847