> From: Tim Bray <[EMAIL PROTECTED]>
> I have neat-looking haystack-y objects which use LineArray geometry. I'd like
> to make some of them glow-y and others dim.
Try making the lines anti-aliased and give the glowy lines brighter colors than
the dim lines. This may give you the effect you are after: the brigher lines
will show through the dimmer lines a bit.
> Normally I'd use an emissiveColor
> in a Material in an Appearance to achieve this effect, but it won't let
> me set the Appearance on the Shape3D because I don't have normals.
If the "lines" in your haystack are are illuminating the other "lines", then
LineArray primitives are the wrong representation. Instead, represent each line
with a cylinder. Place lights along the glowing "lines" to illuminate the other
"lines".
> First
> of all, my mathematical intuition tells me lines don't have normals;
You've got it right: lines primitives are conceptually infinitely thin. If you
want your "lines" to be lightable, make them cylinders.
BTW, it is you can define a polygon and then render it as lit polylines. In
this case, the algorithm is: determine the lit color of each vertex of the
polygon and then draw a shaded line between the vertices. But this is really a
special case of rendering polygons, not really a way of lighting lines.
Doug Gehringer
Sun Microsystems
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