Möbius Strip Animation

[glv]

Seamless Möbius strip:

// Author:      GLV
// Date:        2019-08-12 
// Description: Seamless Mobius strip
// 2 extra transparent QUAD_STRIPS added to acheive this

PShape m;
float thX, thY, thZ;
float x, y, z;
int steps;
int addStep = 2; // Change this to -1, 0, 1, 2

public void settings()
  {  
  size(1280, 1024, P3D);
  }

public void setup()
  {
  ortho();
  }

public void draw()
  {  
  background(0);
  lights();
  surface.setTitle(str(frameRate));
  
  thY += TAU/1000;
  thX += TAU/2000;
  thZ += TAU/1000; 
 
 pushMatrix();
  translate(width/2, height/2);
  rotateY(thY);
  rotateX(thX);
  rotateZ(thZ);  

  noStroke();
  mobius(100, 300, 80, 0);
  shape(m);   
 popMatrix();
  }
 
public void mobius(int steps, float r, float v, float u)
  { 
  m = createShape();
  m.beginShape(QUAD_STRIP);
  for (int step = 0; step < (steps+1) + addStep; step++) // 2 steps added for seamless mobius strip
    {
    u = step*(TAU/steps);  

    if (step > steps)
      m.fill(color(255, 128, 0, 0));   //100% transparent
    else
      m.fill(color(255, 128, 0, 255)); //100% opaque
     
    mobEq(r, -v, u);
    m.vertex(x, y, z);

    mobEq(r, v, u);
    m.vertex(x, y, z);
    }
  m.endShape();
  }

public void mobEq(float radius, float v, float u)
  { 
  x = (radius + v * cos(u/2)) * cos(u);
  y = (radius + v * cos(u/2)) * sin(u);
  z = v * sin(u/2);
  }