Draw an irregular cylinder-style shape in 3D

Question

Hi All
I am new in java 3D. I got such a situation that I have the following data:
point101: (0, 0.3f, 0.4f) // degree:0; radius:0.3f; Z: 0.4f
point102: (10, 0.2f, 0.4f)
point103: (20, 0.35f,0.4f)
point201: (0, 0.35f, -0.4f)
point202: (10, 0.32f, -0.4f)
point203: (20, 0.4f, -0.4f)
I used QuadArray to draw this shape. However, when I change the view point with mouse, some parts were invisible on the screen.
I guess QuadArray is not correct, is it?
Any help will be appreciated.
David
My code attached here:
private Geometry shapeGeometry() {
QuadArray geo;
int N = 8;
int totalN = 4*N;
Point3f coords[] = new Point3f[totalN];
Color3f colors[] = new Color3f[totalN];
Color3f red = new Color3f(1.0f, 0.0f, 0.0f);
float[] r ={0.3f, 0.35f,0.2f,0.32f,0.35f,0.4f,0.3f,0.35f,0.3f, 0.3f,0.36f,0.3f,0.35f,0.4f,0.3f,0.5f};
float w = 0.4f;
int n;
double a;
float x, y;
x = (float) (r[0] * Math.cos(0));
y = (float) (r[1] * Math.sin(0));
coords[0] = new Point3f(x, y, -w);
coords[1] = new Point3f(x, y, w);
for(int i=0; i<colors.length; i++)
colors[i] = red;
for(a = 0,n = 1; n < N; a = 2.0*Math.PI/(N-1) * ++n){
x = (float) (r[2*n] * Math.cos(a));
y = (float) (r[2*n+1] * Math.sin(a));
coords[4*n-2] = new Point3f(x, y, w);
coords[4*n-1] = new Point3f(x, y, -w);
coords[4*n] = new Point3f(x, y, -w);
coords[4*n+1] = new Point3f(x, y, w);
x = (float) (r[0] * Math.cos(0));
y = (float) (r[1] * Math.sin(0));
coords[4*N-2] = new Point3f(x, y, w);
coords[4*N-1] = new Point3f(x, y, -w);
geo = new QuadArray (totalN,
TriangleFanArray.COORDINATES|TriangleFanArray.COLOR_3);
tfa.setCoordinates(0, coords);
tfa.setColors(0,colors);
return geo;
}

Answer 1

oops: I don't know how to draw the top and bottom of the shape. Any one can tell me how to do it? Thanks