PDA

View Full Version : Polygon faces problem



Ironye
04-01-2003, 12:02 PM
Hello,

Here is the screenshot for my question:

http://www.ironye.com/pages/trash.html


After drawing a closed shape with the bezier tool I extruded it. Then when I apply bevel, bend or other tools I get an irregular surface.

I have drawn the shape in a clockwise direction and it only contained a few anchor points.

I also tried bringing in the same shape from Illustrator and ended up with the same results.

Does anyone have any suggestions on how to get rid of the wrinkles that are caused?

Thanks,

Ironye

eblu
04-01-2003, 12:14 PM
try selecting the polygon that was beveled (the one with more than 4 points in it) hit "x" on the keyboard, and then hit "v" on the keyboard...
does this help?

mbaldwin
04-01-2003, 12:36 PM
The kidney shaped poly(the one you extruded) is more than 3 or 4 points. That's not a problem in itself, it's just that in order to render the poly, LW(maybe even open GL)has to triangulate it. and what you see is a 3point poly fan pattern emerging across the face of this poly.

I would split this top poly into a number of smaller ones, where you force a subdevision of your kidney shape into subsections that are more square in nature.

The old-school rule of thumb for triangulation, was to keep triangle to less than a 5:1 ratio. Any triangle polys extremely long and splintery will give you problems once the computer tries smoothing them at render time.

hope this helps.

-m

eblu
04-01-2003, 12:52 PM
mbaldwin,
thats not it at all.
LW has no difficulty rendering polys with more than 4 points.
the problem, crops up when the poly is beveled. and thats the important clue.
if you look at the surface for this object, its more than likely being Smoothed, and whats more, the angle is probably set to 89 degrees. This means that any contiguous polys that have a join that is less than 89 degrees, will appear to be smooth when they are rendered. This makes otherwise flat, contiguous, and not in the same plane polygons try to look like they are smooth from edge to edge, creating warping, and stretching.
Before the poly was beveled, the angle of the join between the front and sides of the object was 90 degrees, ie: it is not smoothed by the renderer.

by cutting and pasting the kidney shaped polys, we force LW and modeller to NOT smooth them with the bevel, because now the kidney shaped polys are not contiguous with anythinging else. this creates a nice clean edge between the bevel and the kidney shaped polys, and leaves the kidney shaped polys nice and clean.

Another way to do this would be to turn down the smoothing angle, or turning off smoothing altogether. Its probably not a good idea to turn off the smoothing angle because it looks like the object is supposed to appear smooth, and turning down the smoothing angle can cause other problems. So the cleanest, most efficient, and Most explicit solution is to cut and paste the kidney shaped polys.

in addition, its also a good idea to cut and paste the bevel as well, this creates a similar sharp definition between the extrusion and the bevel, and makes any specular highlights much more attractive.