如何在处理上使弹跳球与矩形阵列碰撞？

Question

im trying to make the bouncing ball bounce on the arrays of rectangles. I've looked at various other codes but cant seem to find a solution. Would appreciate any help!!!

Basically, i want the bouncing ball to recognise that theres the rectangles there and for it to be able to jump onto the rectangles.

PVector location;  // Location of shape
PVector velocity;  // Velocity of shape
PVector gravity;   // Gravity acts at the shape's acceleration
PVector upwardForce;
PImage bg;
int radius = 10, directionX = 1, directionY = 0;
float x=20, y=20, speed=0.5;
int xarray[] = new int[20];
int  yarray[] = new int[20];

// =========================================================

void setup() {
  size(380,750);
  location = new PVector(100,50);
  velocity = new PVector(0.0,2.1);
  upwardForce = new PVector(0.0,-10.0);

  gravity = new PVector(0,0.4);
  bg = loadImage("bg.png");
  bg.resize(1600,1600);
  background(0);
  for(int i =0; i< 20;i++){
     xarray[i]= i*100;
     yarray[i] = 750-int(random(10))*50;
  }

}
int xd =0, yd=0;
void draw() {
  background(0);
    noStroke();
   xd--;
   yd++;
    // display image twice:
  image(bg, y, 0);
  image(bg, y+bg.height, 0);
  // pos 
  y--;
  if (y<-bg.height) 
    y=0;

    for (int i = 0;i< 20;i++){
      if (xarray[i] <100 && xarray[i]+100 >100){
         fill(255,0,0); 


      }
      else {
        fill(255); 
      }
       rect(xarray[i],yarray[i],100,1200);
       fill(255);
       xarray[i]=xarray[i]-4;
       //yarray[i]=yarray[i]+1;
       if (xarray[i] + 100 < 0){
          xarray[i]+=2000; 
         // yarray[i]-=850;
       }

    }


   // changing Position
  x=x+speed*directionX;
  y=y+speed*directionY; 
  // check boundaries
  if ((x>width-radius) || (x<radius))
  {   
    directionX=-directionX;
  }
  if ((y>height-radius) || (y<radius))
  {   
    directionY=-directionY;
  } 
  // draw
  // if(direction==1)

  // Add velocity to the location.
  location.add(velocity);
  // Add gravity to velocity
  velocity.add(gravity);

  // Bounce off edges
  if ((location.x > width) || (location.x < 0)) {
    velocity.x = velocity.x * -1;
  }
  if ((location.y > height) || (location.y < 0)){
    // We're reducing velocity ever so slightly 
    // when it hits the bottom of the window
    velocity.y = velocity.y * -0.95; 
    location.y = height;
  }

  // Display circle at location vector
  stroke(255);
  strokeWeight(0);
  fill(255);
  ellipse(location.x,location.y,30,30);

}

 void keyPressed()
        { 
         velocity.add(upwardForce);
        }

Answer 1

The best advice we can give you is to break your problem down into smaller steps and to take those steps on one at a time.

For example, can you create a simple sketch that just shows a single hard-coded circle and a single hard-coded rectangle? Now add some code that prints a message to the console if they're colliding. You're going to have to do some research into collision detection , but here's a hint: a common technique is to treat the ball as a rectangle, so you can do rectangle-rectangle collision detection.

Get that working perfectly by itself, and then work your way forward in small steps. Can you add a second rectangle to your sketch? How about a third?

Then if you get stuck, you can post a MCVE (not your whole project, just a small example) along with a more specific question. Good luck.

Answer 2

Here's a few suggestions:

You're best off using a Rectangle class. That way, you don't have to store the locations in an array, and the collide function can be a method of the class. It's easier to just call the positions of the rectangles "x" and "y", but this would obviously conflict with the x and y global variables which you declared at the top of the code. Assuming that you would want to make the ball bounce if it collided, you would need to have a "ballLastx" and a "ballLasty" in order to keep track of which direction the ball came from. You would also need to store the Rectangles in an array or arrayList. It would be something like this:

PVector lastLocation;
Rectangle[] rects;

As for the rectangle class, here's how it would probably look like this:

class Rectangle {
  float x, y;
  Rectangle(float x_, float y_) {
    x = x_;
    y = y_;
  }

  void show() {
    //Displays rectangle
    if (x < 100 && x+100 > 100) fill(255,0,0); 
    else fill(255); 
    rect(x,y,100,1200);

    fill(255);
    x=x-4;
    if (x + 100 < 0) x+=2000; 
  }

  private boolean insideX(PVector pos) {
    return (pos.x + 15 >= x && pos.x - 15 <= x+100);
  }

  private boolean insideY(PVector pos) {
    return (pos.y + 15 >= y && pos.y - 15 <= x + 1200);
  }

  boolean collidedX() {
    //Detects if the ball has collided along the x-axis
    return ((insideX(location) && !insideX(lastLocation)) && insideY(location))
  }

  boolean collidedY() {
    //Detects if the ball has collided along the y-axis
    return ((insideY(location) && !insideY(lastLocation)) && insideX(location))
  }
}

And then, in your setup function, you could declare the Rectangle classes in a for-loop:

//declare the rects array
rects = new Rectangle[20];

//declare each item of the rects array to be a Rectangle
for(int i = 0; i < rects.length; i++) {
  rects[i] = new Rectangle(i*100, 750-int(random(0,10))*50;
}

In order to detect the collision and to bounce the ball, you would need to loop through all of the Rectangles and see if the ball should bounce off any of them:

boolean bouncex = false;
boolean bouncey = false;

//see if any of the rects are colliding with the ball
for(Rectangle r : rects) {
  if(r.collidedX()) bouncex = true;
  if(r.collidedY()) bouncey = true;
}

//if any are colliding, bounce the ball
if(bouncex) velocity.x = -velocity.x;
if(bouncey) velocity.y = -velocity.y;

Finally, don't forget to set the lastLocation PVector to the current location, just before moving the current location:

lastLocation = location.copy();

//move the ball...

Hope this was helpful!