[osg-users] Reference frame

Paul Martz pmartz at skew-matrix.com
Wed Sep 10 13:07:19 PDT 2008


> What is the purpose of OSG to specify them separately as follows:
> 
> osg::Transform::RELATIVE_RF. 

In short, if you don't know whether you want RELATIVE or ABSOLUTE, then you
probably want RELATIVE.
 
RELATIVE is for the typical case where you have a Camera node that specifies
the view, and other transforms (below the Camera in the scene graph
hierarchy) that place objects in the world coordinate system. This is the
"view" and "model" transforms from which the OpenGL "ModelView" matrix gets
its name. In this case, the model transform nodes need to specify RELATIVE
so that OSG will concatenate them with the view matrix from the Camera node.

You might also want to use RELATIVE to create some type of "robot arm" scene
graph in which transformations occur relative to each other.

This is all fairly basic 3D graphics so I'll recommend you purchase a
standard 3D text such as "Real Time Rendering" or "3D Graphics Principles
and Practice"; see the recommended reading in the Quick Start Guide.

Paul Martz
Skew Matrix Software LLC
http://www.skew-matrix.com
+1 303 859 9466




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