hi,
I've got a problem with the source exposed in this site in learning-3D-ShapeTransorm section.
I simple wanted to switch the cilinder height orientation through the y-axis (in the source it is oriented through the z-axis) so I exchanged the content of  vertices[].y  with vertices[].z .
The lateral faces of the cilinder are well drawn but the ends simple disappeared and I don't know why (and this happen only for certain values of the variable pts-number of lateral segments, for example pts=3,7,8,300,18)

help me please

THIS IS THE SOURCE TO CALL IN THE DRAW method: playing with pts variable you can see the problem (for example turning it from 5 to 7)


void cilindro_penta(){
 //------------------------------------------
 // PYRAMID PARAMETERS
 //------------------------------------------
 
 //# base vertices  
 int pts = 18;
 
 //don't change this!!!
 float angle = 0;
 
 //radius amplitude;    
 float radius = 20;
 
 //pyramid height
 float cylinderLength = radius-5;
 
 // initialize vertex arrays
 PVector vertices[][] = new PVector[2][pts+1];

 // fill arrays
 for (int i = 0; i < 2; i++){
   angle = 0;
   for(int j = 0; j <= pts; j++){
     vertices[i][j] = new PVector();
     vertices[i][j].x = cos(radians(angle)) * radius;
     vertices[i][j].z = sin(radians(angle)) * radius;
     vertices[i][j].y = cylinderLength;
     // the .0 after the 360 is critical
     angle += 360.00/pts;
   }
   cylinderLength *= -1;
 }

 // draw cylinder tube
 beginShape(QUAD_STRIP);
 for(int j = 0; j <= pts; j++){
   vertex(vertices[0][j].x, vertices[0][j].y, vertices[0][j].z);
   vertex(vertices[1][j].x, vertices[1][j].y, vertices[1][j].z);
 }
 endShape();

 //draw cylinder ends
 for (int i = 0; i < 2; i++){
   beginShape();
   for(int j = 0; j < pts; j++){
     vertex(vertices[i][j].x, vertices[i][j].y, vertices[i][j].z);
   }
   endShape(CLOSE);
 }
}