Limit Scale ignores negative numbers #38167

New Issue

bassam kurdali · 2014-01-11T22:55:41+01:00

bassam kurdali commented

2014-01-11 22:55:41 +01:00

System Information
GNU/Linux 64 bit (fedora 20) Intel CPU, Nvidia GPU

Blender Version
Broken: bbab2ec 2014-01-10
Worked: (optional)

Short description of error
Limit Scale seems to use absolute values for limiting, allowing objects and bones to have negative scale values even if limit is >= 0

Exact steps for others to reproduce the error
Create a Cube
Add a limit scale on e.g. X, lower value 0 upper value 1 (for example again)
Click 'For Transform' in the constraint just to see it quickly
Scale the Cube down on X: note it skips past 0 to negative values, all the way to negative 1

alternative just load the linked file and scale the cube.limitscale.blend

**System Information** GNU/Linux 64 bit (fedora 20) Intel CPU, Nvidia GPU **Blender Version** Broken: bbab2ec 2014-01-10 Worked: (optional) **Short description of error** Limit Scale seems to use absolute values for limiting, allowing objects and bones to have negative scale values even if limit is >= 0 **Exact steps for others to reproduce the error** Create a Cube Add a limit scale on e.g. X, lower value 0 upper value 1 (for example again) Click 'For Transform' in the constraint just to see it quickly Scale the Cube down on X: note it skips past 0 to negative values, all the way to negative 1 alternative just load the linked file and scale the cube.[limitscale.blend](https://archive.blender.org/developer/F66914/limitscale.blend)

bassam kurdali commented

2014-01-11 22:55:41 +01:00

Changed status to: 'Open'

bassam kurdali commented

2014-01-11 22:55:41 +01:00

Added subscriber: @BassamKurdali

bassam kurdali commented

2014-01-11 22:56:29 +01:00

Oh, that's limit scale constraint just in case it wasn't obvious :)

Joshua Leung commented

2014-01-12 00:43:52 +01:00

Added subscriber: @JoshuaLeung

Joshua Leung commented

2014-01-12 00:43:52 +01:00

Hi Bassam,

This is actually the second report about this we have in the tracker ;)

We have a bit of a problem when it comes to reliably decomposing negative scale values - we can either say that there are negative values present, or no negative values present. The downside to this that we'd have to say that all values are negative, potentially causing some other problems.

For a while now, I've been starting to wonder whether we need a slightly different approach to passing transforms down the constraint stack. Namely, I may need to put in a system that ends up passing down "managed" transforms alongside the matrices so that we can resolve a good number of the ambiguities: in particular, euler rotation and scaling. It would end up complicating things a lot, especially as far as some constraints (e.g. track to's) where the exact transforms applied are not that simple to map back to individual components, but at least we'd finally be able to solve a few other limitations...

Hi Bassam, This is actually the second report about this we have in the tracker ;) We have a bit of a problem when it comes to reliably decomposing negative scale values - we can either say that there are negative values present, or no negative values present. The downside to this that we'd have to say that all values are negative, potentially causing some other problems. For a while now, I've been starting to wonder whether we need a slightly different approach to passing transforms down the constraint stack. Namely, I may need to put in a system that ends up passing down "managed" transforms alongside the matrices so that we can resolve a good number of the ambiguities: in particular, euler rotation and scaling. It would end up complicating things a lot, especially as far as some constraints (e.g. track to's) where the exact transforms applied are not that simple to map back to individual components, but at least we'd finally be able to solve a few other limitations...

Joshua Leung commented

2014-01-12 00:44:57 +01:00

Changed status from 'Open' to: 'Duplicate'

Joshua Leung closed this issue

2014-01-12 00:44:57 +01:00

Joshua Leung commented

2014-01-12 00:45:33 +01:00

✘ Merged into #37623.

bassam kurdali commented

2014-01-12 06:20:09 +01:00

Aligorith, would love to chat with you (this is an entirely different idea with a different scope) about stackable transforms (an idea used by other software in different ways)
the idea is you could add a transform on the 'stack' (or possibly in a node tree) even after constraints.
for limit constraint this probably has no impact, but it could alleviate some of the other weird issues for constraints with offsets (e.g:
base transform
copy location
extra transform (used to be offset)

anyway, this one is not a show stopper, I should start using the search in our spanking new bugtracker (got too used to the old broken one, sorry)
cheers
Bassam

Aligorith, would love to chat with you (this is an entirely different idea with a different scope) about stackable transforms (an idea used by other software in different ways) the idea is you could add a transform on the 'stack' (or possibly in a node tree) even after constraints. for limit constraint this probably has no impact, but it could alleviate some of the other weird issues for constraints with offsets (e.g: base transform copy location extra transform (used to be offset) anyway, this one is not a show stopper, I should start using the search in our spanking new bugtracker (got too used to the old broken one, sorry) cheers Bassam

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Limit Scale ignores negative numbers #38167