Introduction
To successfully use archive RIB files, also known as pre-baked RIB's, with the RenderManstatements,
ReadArchive
andDelayedReadArchive
it is essential to know the true size and true location of an object before itis "exported" as an archive RIB file from Maya or Houdini. The following notes assume you are working in Maya. First of all its very important to be aware that terminology that has meaning within Maya may have almost no meaning outside of Maya. Because an archive file, in effect, "exports" geometry from Maya to a non-Maya environment ie. RenderMan, we must ensure a Maya model or object is properlyprepared prior to archiving with the mtor plugin.
Freeze Transforms
The move, rotate and scale tools support other illusions - that an object canbe directly manipulated with the mouse. What is, infact, being manipulatedis the coordinate system within which the surface or surfaces that comprisethe object are defined. The "raw" geometry of the surfaces themselves remaintotally uneffected by the move, rotate and scale tools.
The freeze-transform command either adds or multiplies the XYZ data, such as polygonand nurbs control vertices, by the translation, rotationand scale values (ie. transformations) stored in the transformation node of a surface.
Figure 1
Figure 1 shows a 1 x 1 (gray) polygon translated 1 unit up the Y axis - confirmed by its translateY attribute. Either the mtor or Rfm Pro plugin can be usedto generate a RIB file.
Figure 2
The Freeze Transforms command was applied to the polygon - figure 2. Nothingappears to have happened to the polygon but the translateY attribute has returnedto zero.
Carefully comparing the XYZ vertex data of the polygon before and afterfreezing transforms shows that the translation on the Y axis has modifiedthe Y components of the vertices.
© 2002- Malcolm Kesson. All rights reserved.
