Well, I finally tracked down the problem. I was setting the
Transparency attributes like this:
//should be opaque
ta.setTransparency(0.0f);
ta.setTransparencyMode(TransparencyAttributes.NICEST);
a.setTransparencyAttributes(ta);
However, that still leaves transparency enabled...I'm assuming that
plugging 0.0f into the transparency equation as the alpha != 0. To fix,
either leave the TransparencyAttributes on the Appearance null or
ta.setTransparencyMode(TransparencyAttributes.NONE);
Anyway, it wasn't a surface normal problem after all.
kddubb
On Mon, 2004-02-23 at 15:50, Kevin wrote:
> All,
>
> I am a newbie working on a fairly simple Java3D application that
> virtually models networked computer systems. I have a quick question on
> surface normals and how they work in the Java3D framework. But first,
> here is my (limited) understanding of what surface normals are from the
> standard Java3D tutorials, etc so you can correct it if necessary.
>
> Surface normals to me seem to be analogous to the angle of reflection
> for shading purposes in the virtual world. Java3D uses this angle of
> reflection most (visually) by the specular color and shininess
> attributes, but should also be used for determining information for
> diffuse and ambient color.
>
> Problem Background:
>
> Most of my objects in my environment are boxes of different dimensions.
> These boxes could be resized at any moment in the application for a
> multitude of reasons. Because of this interaction the Box primitive
> wasn't very conducive and I decided to create my own Shape3D extension
> that knows how to resize itself in real-time according to my
> parameters.
>
> The Problems:
>
> Now when I use CassattItem3D objects, they render mostly correct except
> that many faces seem partially transparent (I think as a function of
> their surface normals). I don't think that was very clear, so I'll
> state it a different way. The boxes seem to render the correct
> specular, diffuse, ambient colors, but the part of the geometry that
> should be blocked (i.e. the back bottom faces) seem to still affect the
> shading on the front faces. The object has an opaque
> transparency/appearance attribute.
>
> I also have these objects as a part of a TransformGroup with a mouse
> rotator attached so I can view them from different perspectives. As the
> objects rotate, faces seem to keep their specular, diffuse, ambient
> colors. The light is not in the TransformGroup so it should be
> independent of the rotation.
>
> My questions:
>
> 1) Why are the front surfaces appear to be affected by the surface
> normals of the back surfaces
> 2) When I rotate the objects, the faces seem to keep their initial
> specular, diffuse, emissive, and ambient colors even though I am
> rotating them independently of the light source. Why don't the colors
> change in relation to the light source after they are rendered?
>
> Anyway, I hope my questions made sense and I didn't show my stupidity
> too blatantly. I'm attaching the code with the implementation of the
> Box so you can correct, flame, etc. about my implementation. Sorry for
> the messy code, but it has a day and half of trial and error programming
> trying to test interactions out.
>
> thanks in advance for the help...any pointers to tutorials/FAQs on using
> surface normals appreciated.
>
> kddubb
>
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