Thanks for your response. I've attached a small image showing an example of the problem. In the picture you can see a series of brown cylinders embedded in a blue plane with a yellow stripe. All of the cylinders share the same geometry and appearance, and each are scaled down using a transform group to the wanted size. The geometry was obtained from a VRML97 file using vrml97.jar.
The single directional light in this image is shining down perpendicular to the plane from the same side as the view platform, so there is no reason to be seeing any specular color from this angle. There is also a single ambient light. In this case, I didn't change the shininess, but it has no effect even if I set it to 1.
The colors for the brown cylinders are as follows: specular color: (0.0010, 4.7058825E-4, 0.0) diffuse color: (0.7, 0.32941177, 0.0) ambient color: (0.4, 0.1882353, 0.0)
The diffuse color is working well, sinde we can see some shading on the rounded surface of the cylinders. The ambient color is also correct for those cylinders that are brown on the flat surfaces.
For some reason, some of the cylinders are reflecting a bright yellow specular color from their flat surfaces, even though I've set the specular color to nearly black. I know it's the specular color, because if I don't set it (leaving at the default of white), these cylinders will be white on that side.
Also, if I use OrbitBehavior to move the viewplatform around, the cylinders will flip rapidly between brown and yellow on the flat sides (both sides when the light is shining directly from the top), achieving a sort of disco-colors effect. I had to position the viewplatform very carefully to take this picture when some of them were brown and some were yellow. Admittedly, only the very thin cylinders have this problem - the longer cylinders are always shaded correctly.
What results are you expecting?
I'm expecting the specular color to only be shown when the angles between the surfaces, the light and the viewplatform are such that we should be seeing it. I'm expecting the specular color to be the color I set it to, and not a saturated rgb color. And I'm expecting a series of shapes that all share the same appearance component and are all set at the same angle to be the same color and shade.
See Section E.2 of the Java 3D Specification for the complete lighting equations.
Thanks. I looked them over, and they make sense. The only variable that I'm not sure of is the normals to the surfaces, because I didn't calculate them. I just loaded the VRML file, used a recursive method to extract the first Shape3D found, and then used getGeometry to extract its geometryArray. I also iterated through its vertices to get its current size so that I could scale it down to the size I wanted. I then created the appearance object and the series of shape3Ds using the same geometry and appearance component for each one. So there's a chance that the problem is that it's just guessing what the normals are for each surface are and getting confused. But in that case, why does the shading work at all? I'm not sure how to explicitly calculate the normals. I think I have to dump the geometry array coordinates and coordinate indices to a geometryinfo object, generate normals, stripify and then dump back to a geometry array object. I haven't tried this yet.
There are some OpenGL issues with respect to the specular color when applied to textured surfaces.
Isn't a textured surface when you attach an image to it? So how could it have a specular color at all? Or do I have that wrong?
You might try the D3D version of Java 3D to see if that works better for you.
Actually I'm using Linux, but it looks funny in windows too, both OpenGL and D3D. Actually, I just checked it in Windows and it looks even uglier, with no shading at all. Maybe it is a normals problem.
Also, the apparent shape, intensity, and color of specular hightlights can be greatly affected by the gamma correction of your monitor. Make sure they're all displaying the same gamma if you're trying to compare specular highlighting effects.
How could I tell whether that's it? All the other colors on my monitor, including images, look normal.
Thanks for your help.
Monica
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