Tetrahedron

Tetrahedron.pde

class Tetrahedron extends PlatonicSolid {
  float ang = radians(120);

  Tetrahedron() {
    super();
  }

  public ArrayList<PVector> generateVertices () {
    ArrayList<PVector> verticesArray = new ArrayList<PVector>();
    verticesArray.add(new PVector(0, 0, radius));
    verticesArray.add(new PVector(radius * sin(ang) * cos(0), radius * sin(ang) * sin(0), radius * cos(ang)));
    verticesArray.add(new PVector(radius * sin(ang) * cos(ang), radius * sin(ang) * sin(ang), radius * cos(ang)));
    verticesArray.add(new PVector(radius * sin(ang) * cos(2*ang), radius * sin(ang) * sin(2*ang), radius * cos(ang)));
    return verticesArray;
  }

  // compute both solid vertices and pshape
  public void buildShape() {
    vertices = generateVertices();

    shape = createShape();
    shape.beginShape(TRIANGLES);

    // first face
    shape.vertex(vertices.get(0).x, vertices.get(0).y, vertices.get(0).z);
    shape.vertex(vertices.get(1).x, vertices.get(1).y, vertices.get(1).z);
    shape.vertex(vertices.get(2).x, vertices.get(2).y, vertices.get(2).z);

    // second face
    shape.vertex(vertices.get(1).x, vertices.get(1).y, vertices.get(1).z);
    shape.vertex(vertices.get(2).x, vertices.get(2).y, vertices.get(2).z);
    shape.vertex(vertices.get(3).x, vertices.get(3).y, vertices.get(3).z);

    // third face
    shape.vertex(vertices.get(0).x, vertices.get(0).y, vertices.get(0).z);
    shape.vertex(vertices.get(1).x, vertices.get(1).y, vertices.get(1).z);
    shape.vertex(vertices.get(3).x, vertices.get(3).y, vertices.get(3).z);

    // fourth face
    shape.vertex(vertices.get(0).x, vertices.get(0).y, vertices.get(0).z);
    shape.vertex(vertices.get(2).x, vertices.get(2).y, vertices.get(2).z);
    shape.vertex(vertices.get(3).x, vertices.get(3).y, vertices.get(3).z);

    shape.endShape();
  }

  // transfer geometry every frame
  public void drawImmediate() {
    vertices = generateVertices();

    beginShape(TRIANGLES);

    // first face
    vertex(vertices.get(0).x, vertices.get(0).y, vertices.get(0).z);
    vertex(vertices.get(1).x, vertices.get(1).y, vertices.get(1).z);
    vertex(vertices.get(2).x, vertices.get(2).y, vertices.get(2).z);

    // second face
    vertex(vertices.get(1).x, vertices.get(1).y, vertices.get(1).z);
    vertex(vertices.get(2).x, vertices.get(2).y, vertices.get(2).z);
    vertex(vertices.get(3).x, vertices.get(3).y, vertices.get(3).z);

    // third face
    vertex(vertices.get(0).x, vertices.get(0).y, vertices.get(0).z);
    vertex(vertices.get(1).x, vertices.get(1).y, vertices.get(1).z);
    vertex(vertices.get(3).x, vertices.get(3).y, vertices.get(3).z);

    // fourth face
    vertex(vertices.get(0).x, vertices.get(0).y, vertices.get(0).z);
    vertex(vertices.get(2).x, vertices.get(2).y, vertices.get(2).z);
    vertex(vertices.get(3).x, vertices.get(3).y, vertices.get(3).z);

    endShape();
  }
}