Hemisphere attempt

float angle = 0.0;

void setup() {
  size(600, 600, P3D);
}

void draw() {
  background(255);

  translate(width/2, height/2);

  rotateX(angle);
  rotateY(angle);

  drawHemisphere(new PVector(HALF_PI, 0, 0), 100, 60, 60);

  angle += 0.01;
}

void drawHemisphere(PVector rot, float radius, float slicesA, float slicesB) {
  float a, b, x, y, z, da, db;

  da = TWO_PI / slicesA;
  db = HALF_PI / slicesB;

  rotateX(rot.x);
  rotateY(rot.y);
  rotateZ(rot.z);

  noStroke();
  fill(0, 255, 0, 127);
  beginShape(QUAD_STRIP);

  for (b=0; b < HALF_PI; b += db) {

    for (a=0; a < TWO_PI+da; a += da) {
      x = cos(a) * cos(b) * radius;
      y = sin(a) * cos(b) * radius;
      z = sin(b) * radius;

      vertex(x, y, z);

      x = cos(a) * cos(b+db) * radius;
      y = sin(a) * cos(b+db) * radius;
      z = sin(b+db) * radius;

      vertex(x, y, z);
    }

  }

  endShape();


  rotateZ(-rot.z);
  rotateY(-rot.y);
  rotateX(-rot.x);
}