Maxwell Render | Official public forum

Posted: **Mon May 27, 2013 12:33 am**

Hi,
in this script :
http://support.nextlimit.com/download/a ... naround.py

there's a line

camera.setStep(0,newpos,target,up,focalLength,fStop,0);

'target' and 'up' being vectors.

How do I access those vectors best with a standard Maya camera (no target null) ? ( Just searching the values, the rest is clear )
The difficulty I have is that those values are not accessible directly, so I'd have to calculate them via some vector math. Is that the correct / easiest way ?

How was that solved in the maxwell plugin ?

Thanks for any input !

Matt

Posted: **Mon May 27, 2013 9:18 am**

You can obtain the up and forward vectors directly from the world matrix of the camera. To compute the target, normalize the forward vector, multiply it by the center of interest distance (which is an attribute on the camera) and subtract from the position, like in the following MEL snippet:

Code: Select all

float $wm[] = `getAttr camera1.wm`;
float $targetDist = `getAttr camera1.centerOfInterest`;

float $pos[]     = { $wm[12], $wm[13], $wm[14] };
float $up[]      = { $wm[ 4], $wm[ 5], $wm[ 6] };
float $forward[] = { $wm[ 8], $wm[ 9], $wm[10] };

normalize($forward);
float $target[] = { $pos[0] - $forward[0]*$targetDist, $pos[1] - $forward[1]*$targetDist, $pos[2] - $forward[2]*$targetDist };

print ("Position: (" + $pos[0] + ", " + $pos[1] + ", " + $pos[2] + ")\n");
print ("Up:       (" + $up[0] + ", " + $up[1] + ", " + $up[2] + ")\n");
print ("Target:   (" + $target[0] + ", " + $target[1] + ", " + $target[2] + ")\n");

The Maxwell plug-in uses the MFnCamera class, which provides methods for retrieving this information, but internally they just do what I've shown above.

Posted: **Mon May 27, 2013 10:30 am**

Perfect. I'll play with this.

Thank you !

Matt

Maxwell Render | Official public forum

camera target and up vectors for use in pyMaxwell

camera target and up vectors for use in pyMaxwell

Re: camera target and up vectors for use in pyMaxwell

Re: camera target and up vectors for use in pyMaxwell