java如何在处理过程中使弹跳球与矩形阵列碰撞？

1 周，4 日 Questions & Answers 506

我试图让反弹的球在矩形阵列上反弹。我看过其他各种代码，但似乎找不到解决方案。非常感谢您的帮助

基本上，我想让弹跳的球意识到那里有矩形，并且能够跳到矩形上

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); }

# 1 楼答案

以下是一些建议：

最好使用矩形类。这样，就不必将位置存储在数组中，collide函数可以是该类的一个方法。只调用矩形的位置“x”和“y”更容易，但这显然与您在代码顶部声明的x和y全局变量相冲突。假设你想让球在碰撞时反弹，你需要一个“ballLastx”和一个“ballLasty”来跟踪球来自哪个方向。您还需要将矩形存储在数组或arrayList中。应该是这样的：

PVector lastLocation;
Rectangle[] rects;

至于矩形类，下面是它可能的样子：

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))
  }
}

然后，在设置函数中，可以在for循环中声明矩形类：

//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;
}

为了检测碰撞并弹起球，您需要在所有矩形中循环，查看球是否应从其中任何一个矩形中弹起：

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;

最后，在移动当前位置之前，不要忘记将lastLocation PVector设置为当前位置：

lastLocation = location.copy();

//move the ball...

希望这有帮助

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java如何在处理过程中使弹跳球与矩形阵列碰撞？

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