> -----Original Message-----
> From: Discussion list for Java 3D API
> [mailto:[EMAIL PROTECTED]]On Behalf Of Doug Twilleager
> Sent: Thursday, March 28, 2002 12:50 PM
> To: [EMAIL PROTECTED]
> Subject: Re: [JAVA3D] On-the-fly object editing
>
>
> Their are a few of problems with adding this sort of API.
> First, there is no standard low level support for this sort
> of feature. So, at a minimum, we would simply render the model
> twice with some sort of polygon offset. Calculating the appropriate
> polygon offset is another issue, because it is generally model
> specific. Finally, and most importantly, this feature tends to be
> application specific. The outlines that we would draw, would almost
> never be what you really want. So, it makes sense to leave this in
> application space for now.
But let's assume that the user provides the polygon offset unit and factor,
and selects PolygonAtributes.POLYGON_FILLED_OUTLINE, it would still be
*much* more beneficial for the renderer to render each polygon twice rather
than require the application to do it. Basically, I'm wondring if Java3D
could do what is shown in the polyoff.c program in the "RedBook":
...
glEnable(GL_LIGHTING);
glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonOffset(polyfactor, polyunits);
glCallList (list);
glDisable(GL_POLYGON_OFFSET_FILL);
glDisable(GL_LIGHTING);
glColor3f (lineColorR, lineColorG, lineColorB);
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
glCallList (list);
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
...
When you say "there is no standard low level support for this sort of
feature." does that mean that there is no corresponding capability in
DirectX? I could understand that being a feature killer (except for the fact
that things like anti-aliased points and line width are exposed in J3D even
though there isn't DirectX support).
Also, what do you mean by "outlines that we would draw, would almost never
be what you really want"? Are the properties in LineAttributes not specific
enough to describe what is desired?
Thanks!
Simeon Fitch
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