PVector a,b,c,d;

void setup (){
  size(500,500,P3D);
  background(255);
  a = new PVector(20,20,0);
  stroke(0);
  smooth();
}

void draw(){
  background(255);
  translate(-100,mouseY*3,0);
  rotate(radians(-mouseY),radians(mouseX),radians(0),radians(0));
  //noFill();
  int rad = 40;
  //rect(a.x,a.y,width-rad,width-rad);
  translate(0,0,50);
    for (int i = 0; i < 800; i+=rad*2){
        for (int j = 0; j < 800; j+=rad*2){
         fill(255);
         stroke(0,100);
         strokeWeight(1);
         pushMatrix();
           for (int k = 30; k >0; k--){
             ellipse(i,j,k*1.2,k*1.2);
             translate(mouseX/50,mouseY/100,k/3);
           }
          popMatrix();
          strokeWeight(2);
          stroke(0,200);
          line(i,j,0,mouseX,mouseY,-200);  
          strokeWeight(5);
          line(mouseX,mouseY,-200,mouseX,mouseY,-300);
          }
      }
}

Donwload code

int i;
void setup(){
  size(700,700,P3D);
  background(255);
  stroke(0,20);
  noFill();
}

void draw(){
   rect(0,0,width,height);
   fill(255,0.05);
   noStroke();
    pushMatrix();
    translate(width/2,height/2,0);
    rotateX(radians(i));
    rotateZ(radians(i/4));
      //line(0,-100+i/4,0,100+i/4);
      stroke(0,20);
      ellipse(0,-110,20+i/10,20+i/40);
      ellipse(0,110,20+i/10,20+i/40);
      popMatrix();
      i++;
}

Download code

float col = 0.1;
PVector mouse = new PVector(mouseX,mouseY);

void setup(){
  size(1100,700,P3D);
  background(255);
  smooth(8);
}

void draw(){
  translate(150,-50);
  stroke(0,20);
  if (mousePressed==true){
      curve();
  }
}

void curve(){
  noFill();
  beginShape();
  PVector mouse = new PVector(mouseX,mouseY);
    vertex(mouse.x+250, mouse.y+200);
    bezierVertex(mouse.x/20+100, mouse.y/20+200, mouse.x+142, mouse.y+294.0, mouse.x +142.47238, mouse.y+294.0);
    bezierVertex(mouse.x/2+400, mouse.y/2+150, mouse.y, mouse.x, mouse.x/10-100, mouse.y/10+100);
    bezierVertex(mouse.x+18.0, mouse.y*2, mouse.x, mouse.y, mouse.x, mouse.y);
  endShape();
}

Download code

float col = 0.1;
PVector mouse = new PVector(mouseX,mouseY);

void setup(){
  size(1100,700,P3D);
  background(255);
  smooth(8);
}

void draw(){
  stroke(0,20);
  translate(150,100);
}

void mouseDragged() {
    curve();
    }
void curve(){
  noFill();
  beginShape();
  PVector mouse = new PVector(mouseX,mouseY);
  vertex(130.0, 43.0);
  translate(random(-1,1),random(-1,1));
  bezierVertex(230.83664, 25.0, 89.0, -26.0, 130.0, 43.0);
  bezierVertex(171.0, 122.0, 345.0, 84.0, 275.4657, 173.90295);
  bezierVertex(205.9314, 263.8059, mouse.x+18, mouse.y+32, 286, 334.0);
  endShape();
}