BTrace Mesh Follow results in curve rolled into a ball #53912

New Issue

Adam Janz · 2018-01-26T20:52:12+01:00

Adam Janz commented

2018-01-26 20:52:12 +01:00

System Information
Windows 8.1 64 bit; EVGA GTX 970

Blender Version
Broken: (2.79 5bd8ac9)

Short description of error

Hi there,

I'm not sure if this is a bug or a limitation of the addon. Here's what I'm trying to do:

I have an empty following a path, by manually animating the path's evaluation time. I have a cube that is the child of the empty. I select the cube, then select Mesh Follow. Start frame is 256, end frame is 406, same as my timeline. I have selected to trace the Object's origin. Upon clicking "Run", the resulting curve is a twisted up ball far from its starting location. Is this happening because the addon does not recognize an animated parent? Thanks!

**System Information** Windows 8.1 64 bit; EVGA GTX 970 **Blender Version** Broken: (2.79 5bd8ac9) **Short description of error** Hi there, I'm not sure if this is a bug or a limitation of the addon. Here's what I'm trying to do: I have an empty following a path, by manually animating the path's evaluation time. I have a cube that is the child of the empty. I select the cube, then select Mesh Follow. Start frame is 256, end frame is 406, same as my timeline. I have selected to trace the Object's origin. Upon clicking "Run", the resulting curve is a twisted up ball far from its starting location. Is this happening because the addon does not recognize an animated parent? Thanks!

Adam Janz commented

2018-01-26 20:52:12 +01:00

Added subscriber: @AdamJanz

Adam Janz commented

2018-01-26 20:53:02 +01:00

Here are my settings:

Here are my settings: ![BTrace Settings.PNG](https://archive.blender.org/developer/F1990303/BTrace_Settings.PNG)

Philipp Oeser commented

2018-01-26 21:56:42 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2018-01-26 21:56:42 +01:00

This seems to be a known limitation.

You can find this is in the sourcecode

Mesh Follow, trace vertex or faces
Create curve at center of selection item, extruded along animation
Needs to be an animated mesh!!!

it uses ob.location.copy() so constraints, curve parents etc wont work.
( Could be a rather easy change, but this is more of a TODO )

As a workaround you can Bake Action with Visual Keying option to get keyframes (which then BTrace will handle nicely...)

This seems to be a known limitation. You can find this is in the sourcecode > Mesh Follow, trace vertex or faces > Create curve at center of selection item, extruded along animation > Needs to be an animated mesh!!! it uses `ob.location.copy()` so constraints, curve parents etc wont work. ( Could be a rather easy change, but this is more of a TODO ) As a workaround you can [Bake Action ](https://docs.blender.org/manual/en/dev/animation/actions.html#bake-action) with `Visual Keying` option to get keyframes (which then BTrace will handle nicely...)

Philipp Oeser commented

2018-01-26 22:00:03 +01:00

I'll leave this open (but change to TODO) for the time being because I dont know if we have a place on the TODO wiki for addons as well...

lower case commented

2018-01-27 00:19:44 +01:00

Added subscriber: @lowercase

lower case commented

2018-01-27 00:19:44 +01:00

could try a fix... open the file: scripts\addons\btrace\bTrace.py
in lines 669 and 673 change 'matrix_local' to 'matrix_world', that will fix it for vertex and face tracers
change line 684 'g_co = objindex.location.copy()' to 'g_co = objindex.matrix_world.to_translation()'
that is for the object tracer to work

could try a fix... open the file: scripts\addons\btrace\bTrace.py in lines 669 and 673 change 'matrix_local' to 'matrix_world', that will fix it for vertex and face tracers change line 684 'g_co = objindex.location.copy()' to 'g_co = objindex.matrix_world.to_translation()' that is for the object tracer to work

Adam Janz commented

2018-01-27 01:29:26 +01:00

Thanks Philipp for the information and the tip about baking the action first. Also thanks lower case for the python code info... I will have to try that.

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

BTrace Mesh Follow results in curve rolled into a ball #53912