songho,
thank you for your help. I feel encouraged to describe my problem in detail.
I want to have a method that draws a steric polyline. I did it former with POVRAY, it’s easier,
there you define a cylinder with a base point and a top point.
My my method is declared as following :
void drawPolylineWithVertices; NSArray* arr
.
. ;
The related part of the definition is :
int i;
for//i=0;i< arr count-1;i++//
//
get arr objectAtindex:i
extract point array to x, y and z
calculate arcs alphaXY, alphaXZ with point i and i+1
Rotation of the cylinder at the origin
around Y-axis with alphaXZ
around Z-axis with alphaXY
then translate from the origin to x,y,z
//
I use for test three sinus functions at the three axes, you can recognize function , translate is O.K. , but the cylinders do not
point from i to i+1.