@article{Barr:1984:GLD,
number = {3},
volume = {18},
month = jul,
author = {Alan H. Barr},
optkey = {},
optstatus = {url},
abstract = {New hierarchical solid modeling operations are developed, which
simulate twisting, bending, tapering, or similar transformations
of geometric objects. The chief result is that the normal vector
of an arbitrarily deformed smooth surface can be calculated
directly from the surface normal vector of the undeformed surface
and a transformation matrix. Deformations are easily combined in a
hierarchical structure, creating complex objects from simpler
ones. The position vectors and normal vectors in the simpler
objects are used to calculate the position and normal vectors in
the more complex forms; each level in the deformation hierarchy
requires an additional matrix multiply for the normal vector
calculation. Deformations are important and highly intuitive
operations which ease the control and rendering of large families
of threedimensional geometric shapes.},
title = {{G}lobal and {L}ocal {D}eformations of {S}olid {P}rimitives},
localfile = {papers/Barr.1984.GLD.pdf},
doi = {http://doi.acm.org/10.1145/964965.808573},
pages = {2130},
journal = SIGGRAPH84,
year = {1984},
organization = {ACM},
}
