And Egon, yours also doesn't work. Both are turning the car in odd directions, and I think it might be because my +Z is up. Sorry for the mathematical ignorance, but you forget so much after ten years without looking at this stuff much. Now, I'm thinking I'll brush up later. :-)

But here's a question: which method should be faster (yours or paulscode's), even if trivially? Are their results equally reliable?

They're world coordinates. Pointer is taken from the center of the car's child (which is a lot like that target I made for my ship to follow in that other game, if you remember). Direction is a world coordinate that the car has to chase (it's pretty much on rails--I'll come up with a pathfinding algorithm later). So I did this, but the car still doesn't rotate right. Do you have any idea why? And thanks in advance, pal.
SimpleVector a = direction.calcSub(center).normalize();
SimpleVector b = opponentPointer.getTransformedCenter().calcSub(center).normalize();
float lengthC = b.calcSub( a ).length();
float theta = (float) Math.acos( (2.0f - (lengthC * lengthC) ) / 2.0f );

I need to find the theta of the following triangle. The only trigonometry book I kept from school doesn't answer this very well. Can anyone help?

Yeah, I did almost exactly the same thing you did, except that my model is far bigger, and each segment of it is made up of many parts, each of which with different textures. Plus, I loaded my textures before the model (as per jPCT norm) and I never called model.setTexture(Texture). Other than that, I did the same thing, so that leads me to believe that it's the multi-texture thing. Egon?

Thanks for your suggestions, although none of them worked and my images have no background. I even tried the black thing, and setting useAlpha to false. It is supposed to work on the software OpenGL, right? And another question: the docs for setAdditionalColor(java.awt.Color) say it's possible for you to set a color above 255, 255, 255 for lightsources and such, except that the JRE throws an IllegalArgumentException when your values are brighter than white. So what gives?

EDIT: I should specify that this object has a million textures, not just the one. Does that matter?

I'm confused. I want to tell the renderer the color blue should be invisible. Is that doable? And I tried Color.blue.getAlpha() as well to the same result, but I guess you just explained that its alpha would be opaque. But isn't the purpose of the setAlpha(int) method to make a given area transparent?

As usual, thanks a whole lot, Egon. I appreciate all your work, and your engine really rocks.

Not to rush you in any way, Egon, but I was wondering if you already have a beta of 1.18 with that in so that I don't have to do it differently on my code and have to change it later.