With monday.comâ€™s project management tool, you can see what everyone on your team is working in a single glance. Its intuitive dashboards are customizable, so you can create systems that work for you.

Hi,

My linear algreba's a little shaky, hence the question...

I have a non axis aligned box parameterised something like:

vector3 center

vector3 extents

vector3 eulers

To draw this thing I apply transformations like this:

extents -> eulers -> center

ie. scale -> rotate -> translate

I want to recalculate the translate when I update the scale to give the same tranformation such that a particular side of the box remains in the same position.

The box is editable by the user who can pull the edges to scale the box, or use a widget to rotate the box. With zero rotations the box behaves ok, I calculate the center to compensate for the adjusted edge. However when the box is rotated this calculation is not so simple I cannot get the same behaivour, the box moves around.

The end result needs to be a 4x4 matrix that represents the tranformation so there maybe another representation would be better.

Any help really appreciated.

faraz

My linear algreba's a little shaky, hence the question...

I have a non axis aligned box parameterised something like:

vector3 center

vector3 extents

vector3 eulers

To draw this thing I apply transformations like this:

extents -> eulers -> center

ie. scale -> rotate -> translate

I want to recalculate the translate when I update the scale to give the same tranformation such that a particular side of the box remains in the same position.

The box is editable by the user who can pull the edges to scale the box, or use a widget to rotate the box. With zero rotations the box behaves ok, I calculate the center to compensate for the adjusted edge. However when the box is rotated this calculation is not so simple I cannot get the same behaivour, the box moves around.

The end result needs to be a 4x4 matrix that represents the tranformation so there maybe another representation would be better.

Any help really appreciated.

faraz

1 Solution

I think the problem is actually more to do with keeping the opposite edge to the one thats begin moved stationary.

It may be simpler to work by transforming faces/vertices (user experience is the same) then calculate the matrix from the vertices when I need it, maybe with the coord frame defined by the planes since this bit is not performance critical. That way I'm not dealing with a representation based on transformations, I just apply a transformation to vertices as I need it.

hmm...I'll give this ago, thanks for your help (got me thinking about this in a different way!)

faraz

Tackle projects and never again get stuck behind a technical roadblock.

Join Now
-Chris