BGE local space character movement is funky when add is checked #40682

New Issue

Joseph Masaki · 2014-06-18T02:39:32+02:00

Joseph Masaki commented

2014-06-18 02:39:32 +02:00

System Information
MS Windows 7 Home Premium 64-bit SP1
NVIDIA GeForce GT 555M

Blender Version

Broken: 2.71 Release Candidate 2 a19c1be

Although it's been broken since at least 2.67.1 r57348

Short description of error
When motion actuator is set to local and add the the object moves when rotated on Z axis in weird ways (kind of hard to explain.)

Exact steps for others to reproduce the error
Start game engine
Use WASD to move and Q and E to rotate.
Once you rotate over 0° the direction you move is off. If you rotate around 180° your movement becomes very jerky.
local_add_move_bug.blend

**System Information** MS Windows 7 Home Premium 64-bit SP1 NVIDIA GeForce GT 555M **Blender Version** Broken: 2.71 Release Candidate 2 a19c1be Although it's been broken since at least 2.67.1 r57348 **Short description of error** When motion actuator is set to local and add the the object moves when rotated on Z axis in weird ways (kind of hard to explain.) **Exact steps for others to reproduce the error** Start game engine Use WASD to move and Q and E to rotate. Once you rotate over 0° the direction you move is off. If you rotate around 180° your movement becomes very jerky. [local_add_move_bug.blend](https://archive.blender.org/developer/F94600/local_add_move_bug.blend)

Joseph Masaki commented

2014-06-18 02:39:32 +02:00

Changed status to: 'Open'

Joseph Masaki commented

2014-06-18 02:39:32 +02:00

Added subscriber: @JosephMasaki

Inês Almeida commented

2014-06-18 10:21:22 +02:00

Added subscriber: @brita

Sergej Reich commented

2014-06-21 12:31:57 +02:00

Added subscriber: @sreich

Sergej Reich commented

2014-06-21 12:31:57 +02:00

Hmm, the character controller actually rotates the object. I guess there's a problem there or maybe the walk direction is not calculated correctly. I'd start by looking at KX_ObjectActuator.cpp, lines 223-255.

In cases like this it would be good to have some sort of debug visualization. So we could draw things like the walk direction vector and see if it's pointing in the right direction.
I'm not sure how one would do that in the game engine.

Another thing that I noticed is that btKinematicCharacterController::setWalkDirection() can be called with a 0 vectror, but trying to normalize a 0 vector will assert. So there's also a bug here as well.

Hmm, the character controller actually rotates the object. I guess there's a problem there or maybe the walk direction is not calculated correctly. I'd start by looking at KX_ObjectActuator.cpp, lines 223-255. In cases like this it would be good to have some sort of debug visualization. So we could draw things like the walk direction vector and see if it's pointing in the right direction. I'm not sure how one would do that in the game engine. Another thing that I noticed is that btKinematicCharacterController::setWalkDirection() can be called with a 0 vectror, but trying to normalize a 0 vector will assert. So there's also a bug here as well.

Inês Almeida commented

2014-06-22 14:21:36 +02:00

I will ask around for the debug visualization.
@sreich What do you suggest for correcting the call to btKinematicCharacterController::setWalkDirection() with a 0 vector?

I will ask around for the debug visualization. @sreich What do you suggest for correcting the call to btKinematicCharacterController::setWalkDirection() with a 0 vector?

Sergej Reich commented

2014-06-22 14:56:47 +02:00

Added subscriber: @Moguri

Sergej Reich commented

2014-06-22 14:56:47 +02:00

@brita that depends on whether walk direction is allowed to be 0 or not. If it can be zero just check for that and don't call normalize.
I'm not sure what's intendet here, maybe ask @Moguri?

@brita that depends on whether walk direction is allowed to be 0 or not. If it can be zero just check for that and don't call normalize. I'm not sure what's intendet here, maybe ask @Moguri?

Mitchell Stokes commented

2014-07-01 06:18:42 +02:00

I haven't looked much at this yet, but #34349 might be related.

Mitchell Stokes commented

2014-07-11 07:47:12 +02:00

Here is a patch that resets the walk direction every frame (if the feature is enabled). This helps to simplify the character motion actuator. It also gets rid of the automatic normalization to avoid the strange issues in #34349. While it would be a nice feature to have, it is awkward to implement. If users want better control over character physics, they should just use Python.

char_obj_act_fix.diff

As for a walk direction of 0, this is the only way I know of to actually stop a character from moving (short of resetting the whole character controller). So, I think this more a Bullet bug than a Blender bug.

Here is a patch that resets the walk direction every frame (if the feature is enabled). This helps to simplify the character motion actuator. It also gets rid of the automatic normalization to avoid the strange issues in #34349. While it would be a nice feature to have, it is awkward to implement. If users want better control over character physics, they should just use Python. [char_obj_act_fix.diff](https://archive.blender.org/developer/F97445/char_obj_act_fix.diff) As for a walk direction of 0, this is the only way I know of to actually stop a character from moving (short of resetting the whole character controller). So, I think this more a Bullet bug than a Blender bug.

Thomas Szepe commented

2015-04-10 10:11:39 +02:00

Closed as duplicate of #36703

Thomas Szepe closed this issue

2015-04-10 10:11:39 +02:00

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BGE local space character movement is funky when add is checked #40682