[Sidefx-houdini-list] PC cache from Mantra into SOP space?

Simon Barrick simon at primalpictures.com
Sun Aug 17 05:15:44 EDT 2008


Hi Peter, you need the camera projection matrix which normalises everything, I can't remember ever seeing anything about whether you can get access to that in sop vops. You could use a transform vop and transform the 3 axis vectors from object to world and then build the matrix you need from them and invert it. But does transforming a vector into world space in sop context actually mean anything??

Si

-----Original Message-----
From: sidefx-houdini-list-bounces at sidefx.com on behalf of Peter Bowmar
Sent: Sun 17/08/2008 04:33
To: sidefx-houdini-list at sidefx.com
Subject: [Sidefx-houdini-list] PC cache from Mantra into SOP space?
 
Hi,

So, trying to load in a PC file written from a pcwrite() in mantra, into SOPs.

It all works except it's in the wrong space :(


I use a VOP SOP and use "optransform()" (sadly, I can find no equiv
VOP, have to use Inline VOP) which gives me the Camera's transform.
Taking the inverse of that and multiplying it by P makes things
better, but not perfect.

Of course, the .pc file was written after the Camera was moved to the
world 0,0,0 so this is logical.

Here's where my bad matrix knowledge trips me up: I know I need to
munge the optransform() matrix to transform that transform into
"Camera Space" (i.e. camera looking down Z at 0,0,0) but for the life
of me I can't figure out how. Anyone? Mario? :)

Cheers,

Peter B
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