Transformation Matrix To Components

[bashesen]

hi,

I just recently started messing around with the c++ api of maya. The thing i wanted to do (for now) is create a node, which takes a world matrix as input and splits this in the translation, rotation and scale attributes, which will be passed through to the outputs.
After some research i got the matrix in the node so it can be worked with. But I can`t figure out how to extract the attributes back from the matrix which can be written to float-plugs.

this is how far i am now:

MDataHandle inMatrixHandle = data.inputValue(plug);
MMatrix inMatrix = inMatrixHandle.asMatrix();

any help would be appreciated.

Bas

[rob-bateman]

From the main maya menu, goto Windows->Settings Preferences->Plug-in Manager. Load the decompose matrix plugin. Done.

[bashesen]

Thank you for your quick reply...that decomposeMatrix-node looks like it is exactly what i was describing earlier.
Im still curious to how this is coded in the API. My final goal with this project is to make a space-switching node. One which takes multiple matrices as inputs, has a dropdown-menu from which you can select the space and output the translate, rotate and scale values.
Im taking small steps at a time, and one of the first problems i was trying to figure out was reading the inputs and writing the outputs...

I guess it would be possible to make the node input and output matrices and append a decomposeMatrix node to that. But i`d rather see the conversion done internally.

[visualfx]

MTransformationMatrix has methods for extracting all the TRS components of a matrix.

Just so you know, the space switching you described can be achieved through the use of parentConstraints. I would advise you try writing some MEL/Python tools that interact with the parentConstraint node rather than rewriting functionality that already exists. I guarantee it will be a lot less work and will work just as well (...if not a whole lot better)

[joojaa]

QUOTE(BasHesen @ 02/17/09, 08:36 PM) [snapback]301083[/snapback]
I`m still curious to how this is coded in the API.

The code can be found for that if you wish. (i think older mayas ship with the code), but yes its quite straightforward just read the man page of MTransformationMatrix, contains all you need to know really.

But dont write it its just waste of your time and doesnt make you any better as a maya programmer.

QUOTE
Just so you know, the space switching you described can be achieved through the use of parentConstraints.

yes i second that!

QUOTE
I guarantee it will be a lot less work and will work just as well (...if not a whole lot better)

Well atleast its 10-100 times easier to maintain in the future. And api is NOT faster here since the nodes are allready at api level fast or even beyond.

[bashesen]

Thank you for your replies and advice.
Ive looked into ways of rigging space-switching with the nodes already available in maya. From what I understand it is as simple as a parent-constraint with multiple weights and a script which corrects the translates on the switch.
The reason why I still think a genuine space switching node will be benificial is because it streamlines the rigging and keying process. Switching will be done then by adding only one key. Retiming would be easy, as you dont have to worry about forgetting moving keys and the correction translates would update automatically...at least, thats how i see it working. But it will be quite a hassle to get to that point, i agree with you there...
Ill just mess around with it for a couple of days. If progress is too slow I`ll have no choice but to abandon the project and write some MEL tools instead.

[joojaa]

QUOTE(BasHesen @ 02/18/09, 11:22 AM) [snapback]301143[/snapback]
The reason why I still think a genuine space switching node will be benificial is because it streamlines the rigging and keying process. Switching will be done then by adding only one key.

Well, your kind of underestimating how maya works here. You don't actually need the use the wights to switch space. You can instead put choice node between the inputs of the parent constraint too and then just swap the parent of the constraints one input instead. This achivhieves same thing, and in the end is no more convoluted than anything you would do.

So even if you can think its beneficial under those limitted you think parameters ist still not true in the big picture of how maya works. As nothing states the input of what you use should need to be the one you need.

Same applies to the decompose matrix node, you can put choice node before it and input many a parent matrix into it for any arbitrary switching.

However the benefit of the aprent contraint is IF (and yes this if allways is the one ythat kills you in the end) a user wants to at later stage interpolate this value for any obscure reason you can always allow him to do so.

We just see trough the description, and we are saying if that's your border info then don't use api, you allready have all this. Yes you can make it no prob but its waste of time.

PS: having 20 nodes in vanilla maya is MUCH better than having 1 own written node. Do not deign nodes to collapse several nodes into one, its just waste of maintenance time. Use containers instead.