p5.j​​s中两个不同形状的物体碰撞检测

Question

I'm trying to have my Particle object collide and reflect off my Slate object.

If I wanted to use an ellipse, it would be simple because I could just create a radius variable - can't do that with a rectangle.

It's something to do with the distance variable, I just can't figure it out.

var div;
var movers;


function setup() {
  createCanvas(windowWidth,windowHeight);
  background("#FDEDEB");
  div = new Slate();
  movers = new Particle();
}

function draw() {

  background("#FDEDEB");

  div.display();

  movers.display();
  movers.update();
  movers.move();

  if (movers.hits(div)) {
    console.log("hit");
  }

}


function Slate() {

  this.x = 30;
  this.y = height/2;

  this.display = function() {
  noStroke();
  fill("#DF4655");
  rect(this.x,this.y, 700, 200);

  }
}

function Particle() {
  this.pos = createVector(10,0);
  this.vel = createVector(0,0);
  this.acc = createVector(0.01,0.01);
  this.history = [];

  this.display = function() {
    fill("#DF4655");
    point(this.pos.x,this.pos.y);

    //beginShape();
    for(var j = 0; j < this.history.length; j++) {
      var pos = this.history[j];
      ellipse(pos.x,pos.y, 5, 3);
    }
    //endShape();

  }

  this.update = function() {

    var v = createVector(this.pos.x,this.pos.y);
    this.history.push(v);
    if (this.history.length > 10) {
      this.history.splice(0,1);
    }
  }

  this.hits = function(div) {
        // BOUNCE OFF SLATE
      var d = dist(this.pos.x,this.pos.y,div.x,div.y);
      if (d < 0) {
        console.log('hits');
      }
  }


  this.move = function() {

    this.pos.add(this.vel);
    this.vel.add(this.acc);
    this.vel.limit(10);

    for (var i = 0; i < this.history.length; i++) {
      this.history[i].x += random(-2,2);
      this.history[i].y += random(-2,2);
    }

  }
}

Answer 1

If the particle is a point (or can be represented as a point), you need to use point-rectangle collision detection. Basically you would need to check whether the point is between the left and right edges and the top and bottom edges of the rectangle.

if(pointX > rectX && pointX < rectX + rectWidth && pointY > rectY && pointY < rectY + rectHeight){
  //the point is inside the rectangle
}

If the particle is an ellipse and you need to factor in the radius of that ellipse, then you're better off representing the particle as a rectangle, just for collision purposes. Then you can use rectangle-rectangle collision detection. This is also called a bounding box, and it's one of the most common ways to handle collision detection.

if(rectOneRight > rectTwoLeft && rectOneLeft < rectTwoRight && rectOneBottom > rectTwoTop && rectOneTop < rectTwoBottom){
  //the rectangles are colliding
}

Shameless self-promotion: I wrote a tutorial on collision detection available here . It's for Processing, but everything is the same for P5.js.