iphone - 如何在box2d iPhone中手动制作一个动态物体(球)进入盒子

Question

由于我是 cocos2d 的新手，而且我很挣扎。任何人都可以建议我如何解决这个问题。

1. 我有 3 个盒子(它们是运动体)

2. 还有多个球(它们是动态物体)，每个球都有一个标签值(盒子编号)。

3. 我在射球位置和盒子之间有一些障碍物(运动体)。

场景是我将随机获得盒子编号，例如:2(第二个盒子)，并将其设置为球的标签值。即使球撞到障碍物，球也应该准确地进入第二个盒子。如果我得到下一个球的盒子编号为 3，则球应该进入第三个盒子。

有人可以推荐我吗

谢谢你， 莫尼什

Answer 1

这是一个简单的辅助类，用于创建球并返回。您可以使用类似的方法来制作盒子。

//
//  Ball.h
//  BouncingBall
//
//  Created by Omar Hussain on 8/12/10.
//  Copyright 2010 __MyCompanyName__. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "cocos2d.h"
#import "Box2D.h"

class Ball : public CCSprite {
public:
    CCSprite *sprite;
    b2BodyDef ballBodyDef;
    b2Body *ballBody;
    b2FixtureDef ballShapeDef;
    b2Fixture *fixture;
    Ball(b2World *world);
    b2Vec2 disp;
    CCSprite *shadowBall;
    b2World *world;
    bool isAnimating;
    void SetBallOverlap(bool willOverlap, int scale);
    void Destroy();
};


#import "Ball.h"

#define Density 1.0f
#define Friction 1.0f
#define Restitution 0.8f
#define PTM_RATIO 32
#define SpriteRadius 40.5


Ball::Ball(b2World *world){
    this->world = world;
    this->sprite = [CCSprite spriteWithFile:@"5.png"];
    [sprite setPosition:ccp(160,460)];  
    this->isAnimating = false;
    //Set up sprite
    ballBodyDef.type = b2_dynamicBody;
    ballBodyDef.position.Set(160/PTM_RATIO, 460/PTM_RATIO);
    ballBodyDef.userData = sprite;
    this->ballBody = world->CreateBody(&ballBodyDef);

    b2CircleShape circle;
    circle.m_radius = SpriteRadius/PTM_RATIO;

    ballShapeDef.shape = &circle;
    ballShapeDef.density = Density;
    ballShapeDef.friction =Friction;
    ballShapeDef.restitution = Restitution;
    this->fixture = this->ballBody->CreateFixture(&ballShapeDef);

    //this->shadowBall = [TSprite spriteWithFile:@"ball_shadow.png"];


}
void Ball::SetBallSize(int scale){
    this->ballBody->DestroyFixture(fixture);
    this->world->DestroyBody(ballBody);

    ballBodyDef.type = b2_dynamicBody;
    ballBodyDef.position.Set(160/PTM_RATIO, 460/PTM_RATIO);
    ballBodyDef.userData = sprite;
    this->ballBody = world->CreateBody(&ballBodyDef);
    float  correctedScale = scale/9.0;
    b2CircleShape circle;
    circle.m_radius = (correctedScale *SpriteRadius)/PTM_RATIO;

    ballShapeDef.shape = &circle;
    ballShapeDef.density = Density;
    ballShapeDef.friction = Friction;
    ballShapeDef.restitution = Restitution;
    this->fixture = this->ballBody->CreateFixture(&ballShapeDef);
    //this->shadowBall.scale = scale;
    this->sprite.scale = correctedScale;
}
void Ball::SetBallOverlap(bool willOverlap, int scale){
    this->world->DestroyBody(ballBody);

    ballBodyDef.type = b2_dynamicBody;
    ballBodyDef.position.Set(160/PTM_RATIO, 460/PTM_RATIO);
    ballBodyDef.userData = sprite;
    this->ballBody = world->CreateBody(&ballBodyDef);
    float  correctedScale = scale/9.0;
    b2CircleShape circle;
    circle.m_radius = (correctedScale *SpriteRadius)/PTM_RATIO;

    ballShapeDef.shape = &circle;
    ballShapeDef.density = Density;
    ballShapeDef.friction = Friction;
    ballShapeDef.restitution = Restitution;
    if(willOverlap)
        ballShapeDef.filter.groupIndex = 1;
    else 
        ballShapeDef.filter.groupIndex = -1;
    this->ballBody->CreateFixture(&ballShapeDef);
}
void Ball::Destroy(){
    this->ballBody->DestroyFixture(fixture);
    this->world->DestroyBody(ballBody);
}