float side = 100;
float rad60=60*PI/180;

float rotx = PI/4;
float roty = PI/4;

Pt p1 = new Pt(-side/2,0,0);
Pt p2 = new Pt(0,sin(rad60)*(-side),0);
Pt p3 = new Pt(side/2,0,0);
Pt p4 = new Pt(0,sin(rad60)*(-side)*.5,sin(rad60)*(side));
Pt p5 = new Pt(side,0,0);
Pt p6 = new Pt(side*1.5,sin(rad60)*side,0);
Pt p7 = new Pt(2*side,0,0);
Pt p8 = new Pt(side*1.5,sin(rad60)*side*.5,sin(rad60)*side);

void setup() {
  size(800,600,P3D);
}
void draw() {
  background(0);
  translate(width/2.0, height/2.0, -100);
  rotateX(rotx);
  rotateY(roty);
  drawtetrahedron(230,0,0,p1,p2,p3,p4);
   drawtetrahedron(100,0,100,p5,p6,p7,p8);
}
void drawtetrahedron(int colR, int colG, int colB,Pt t1,Pt t2, Pt t3, Pt t4) {
  fill(colR,colG,colB);
   beginShape(TRIANGLES);
   vertex(t1.x,t1.y,t1.z);
   vertex(t2.x,t2.y,t2.z);
   vertex(t3.x,t3.y,t3.z);    
  endShape();
  beginShape(TRIANGLES);
   vertex(t1.x,t1.y,t1.z);
   vertex(t4.x,t4.y,t4.z);
   vertex(t3.x,t3.y,t3.z);    
  endShape();
   beginShape(TRIANGLES);
   vertex(t1.x,t1.y,t1.z);
   vertex(t4.x,t4.y,t4.z);
   vertex(t2.x,t2.y,t2.z);    
  endShape();
    beginShape(TRIANGLES);
     vertex(t2.x,t2.y,t2.z);
     vertex(t4.x,t4.y,t4.z);
       vertex(t3.x,t3.y,t3.z);
  endShape();
  
}
void mouseDragged() {
  float rate = 0.01;
  rotx += (pmouseY-mouseY) * rate;
  roty += (mouseX-pmouseX) * rate;
}
class Pt {
  float x,y,z;
  Pt (float xx,float yy,float zz) {
    x = xx;
    y = yy;
    z = zz;
  }
  
}