Hi, and sorry that I did not formulate the idea properly.

I wonder if there is an easy way of 'filling in' the space between two polygon shapes, so that they become a solid shape rather than two surfaces?

... or do I have to work with triangles that combine the two corresponding vertex points in a sandwitch of vertex shapes? (that will end up being an awful lot of triangle arrays:(

Here's and example that demonstrates the problem:

import processing.opengl.*;

void setup(){
  size(500, 500, OPENGL);
  background(0);
  fill(20, 150, 200);
  noStroke();
  lights();
  //smooth();
 
  pushMatrix();
  translate(250, 200, 200);
  beginShape(POLYGON);
     curveVertex(10, 10, 10); // I would like to fill the space from this point ...
     curveVertex(20, 30, 10);
     curveVertex(50, 40, 10);
     curveVertex(70, 30, 10);
     curveVertex(25, 10, 10);
     curveVertex(16, 5, 10);
  endShape();
  popMatrix();
 
  fill(20, 100, 10);
  pushMatrix();
  translate(250, 200, 150);
  beginShape(POLYGON);
     curveVertex(15, 15, 10); //... with this point aso.
     curveVertex(25, 35, 10);
     curveVertex(55, 45, 10);
     curveVertex(75, 35, 10);
     curveVertex(30, 15, 10);
     curveVertex(121, 10, 10);
  endShape();
  popMatrix();
}