#Shrink Wrap
15-Jul-94 14:58:14
Sb: #112904-#Shrink Wrap
Fm: M. G. BATCHELOR 71532,1214
To: James Franssen 72650,3677
James,
First of all, I have used programs with patch "shrinkwrap" functions as well,
and also would like to see that function in 3DS. Secondly, I believe you are
misunderstanding SKIN.axp. If you have ever used a spline modeler, you are no
doubt familiar with creating lattices (hulls) to define/control the curves.
With SKIN.axp, you use 3DS's native polygon tools to construct/edit a lattice
for spline patches that you will never see in wireframe. The spline-fit
functions happen in the renderer and ultimately create a bunch of triangles to
render. There are rescrictions wrt building the lattices, though. In general,
the vertices must be ordered in a certain way, and lofting with optimization &
weld OFF will produce this ordering correctly. You can use some other
primitives as per the doc's with vertex modifications. Slice.axp is NOT
intended to make ANY OBJECT "skinnable".
Your experiments with Skin.axp are probably "rough" due to using too high a
step level on your shapes and/or path in the lofter. While working in 3DS's
NATIVE modeling system, you likely want/need the step level to be higher to
produce perimeter smoothness in the object. But with Skin.axp, the idea is to
use a minimum of control points for the lattice. With splines (especially
B-Splines), you achieve maximum smoothness via minimum control vertices. A
simple 8-vertice cube with 0 step setting will produce a capped cylinder – very
smooth. After you have lofted your lattice(s), you can manipulate them at any
level – no problem – just don't delete any vertices in the process. Check out
my Cowboy head Skin model on the disk – it is reasonably detailed & smooth, yet
only uses 680 vertices for the skull.
For your example object, deform the original properly constructed lattice
manually or with any routine that does not add/delete vertices, to create your
morph target(s). Keep in mind, using MINIMUM control vertices, your "blob" will
look rough in wireframe, but should render very smoothly. With the parameters
in the Skin dialog, you can control tension and bias for the smoothness
direction as well as resolution.
It works well. Hope this helps some.
BILL