Shape can't be showed with light?!

Question

I create my own Geometry, log, using TriangleFanArray and TriangleStripArray and attach material to it. However, it can only get outline, but no shape. When I change my Geometry to Cylinder, it works well. I do Normal my geometry with vector(1.0f, 0.0f, 0.0f). Honestly, I don't know what that means, just copy from an example that I read.
parts of my code Attached here:
Geometry create
tfa = new TriangleFanArray (totalN,
TriangleFanArray.COORDINATES|TriangleFanArray.NORMALS,stripCounts);
tfa.setCoordinates(0, coords);
tfa.setNormals(0, normal);Add to TransformGroup
Shape3D shape1 = new Shape3D();
cone1.setGeometry(log());
cone1.setAppearance(logAppear);
Shape3D shape2 = new Shape3D();
cone2.setGeometry(twoSide());
cone2.setAppearance(logAppear);
logBG.addChild(logTGT1);
logTGT1.addChild(logTGR1);
logTGR1.addChild(shape1);
logTGR1.addChild(shape2);Anyone can tell me what is wrong here? Thanks in advance.
David

Answer 1

Hi,
trial an error with vector algebra can be a tiring task...
The normal vector is the vector, which is orthogonal to the polygon associated with that vertex, having a length of 1. The normal vectors are crucial for the calculation of scene lighting.
It's the developers task to calculate these normals and no one checks these resulting vectors for their correctness (sometimes it can be useful to intentionally use "incorrect" normals, but that's another topic).
But in almost every case (1.0f, 0.0f, 0.0f) will not be a suitable value.
Normals are usually calculated using the dot product of two "edge vectors" of a polygon and then normalizing the result.
Lights need to have influencing bounds set, otherwise they won't work. So in case you didn't do that somewhere else in you code...
Regards
Fleischer