書いた線の上にボールを転がすアプリのサンプル
(XcodeのiOS6 Simulatorで試しています。)
ポイント
・物理エンジンにBox2dを使う （手順はページ末尾）
・２点から、UIViewで直線を作成する。
サンプルコード
#import “ViewController.h”
#import <Box2D/Box2D.h>
#import <QuartzCore/QuartzCore.h>
#define PixelToMeterRatio 16
typedef enum{
FingerTypeCreateBall = 1,
FingerTypeCreateLine,
} FingerType;
@interface ViewController () {
b2World *world;
NSTimer *timer;
FingerType type;
CGPoint start;
CGPoint end;
}
@end
@implementation ViewController
– (void)viewDidLoad
{
[super viewDidLoad];
[self createFingerWorld];
[self start];
[self createTypeSelector];
}
– (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *t = [touches anyObject];
CGPoint p = [t locationInView:self.view];
// ボタンがある場所をクリックした場合はスキップ
if (CGRectContainsPoint(CGRectMake(270, 0, 50, 150), p)) {
[self touchesCancelled:touches withEvent:event];
return;
}
// ボールのときはタッチした場所にボールを生成
if (type == FingerTypeCreateBall) {
[self addBall:p];
}
// ラインのときは、タッチしたところを開始点として保持
if (type == FingerTypeCreateLine) {
start = p;
}
}
– (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *t = [touches anyObject];
CGPoint p = [t locationInView:self.view];
// ボタンがある場所をクリックした場合はスキップ
if (CGRectContainsPoint(CGRectMake(270, 0, 50, 150), p)) {
[self touchesCancelled:touches withEvent:event];
return;
}
// ラインのとき、離したところまでViewを生成
if (type == FingerTypeCreateLine) {
end = p;
[self addLine];
}
}
– (void)start
{
timer = [NSTimer scheduledTimerWithTimeInterval:1.0/60.0 target:self selector:@selector(tick:) userInfo:nil repeats:YES];
}
– (void)createFingerWorld
{
CGSize screenSize = self.view.bounds.size;
b2Vec2 gravity;
gravity.Set(0.0f, –9.8f);
world = new b2World(gravity);
world->SetContinuousPhysics(true);
b2BodyDef groundBodyDef;
groundBodyDef.position.Set(0, 0);
b2Body* groundBody = world->CreateBody(&groundBodyDef);
b2EdgeShape groundBox;
// bottom
groundBox.Set(b2Vec2(0,0), b2Vec2(screenSize.width/PixelToMeterRatio,0));
groundBody->CreateFixture(&groundBox, 0);
// left
groundBox.Set(b2Vec2(0,screenSize.height/PixelToMeterRatio), b2Vec2(0,0));
groundBody->CreateFixture(&groundBox, 0);
// right
groundBox.Set(b2Vec2(screenSize.width/PixelToMeterRatio,screenSize.height/PixelToMeterRatio), b2Vec2(screenSize.width/PixelToMeterRatio,0));
groundBody->CreateFixture(&groundBox, 0);
}
– (void)createTypeSelector
{
// ball type button
UILabel *ballBtn = [[UILabel alloc] initWithFrame:CGRectMake(280, 50, 30, 30)];
ballBtn.text = @”○”;
ballBtn.textAlignment = NSTextAlignmentCenter;
ballBtn.layer.cornerRadius = 5.0;
ballBtn.layer.borderWidth = 2.0;
ballBtn.tag = FingerTypeCreateBall;
ballBtn.userInteractionEnabled = YES;
ballBtn.backgroundColor = [UIColor grayColor];
[self.view addSubview:ballBtn];
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(change:)];
[ballBtn addGestureRecognizer:tap];
// line type button
UILabel *lineBtn = [[UILabel alloc] initWithFrame:CGRectMake(280, 100, 30, 30)];
lineBtn.text = @”—“;
lineBtn.textAlignment = NSTextAlignmentCenter;
lineBtn.layer.cornerRadius = 5.0;
lineBtn.layer.borderWidth = 2.0;
lineBtn.tag = FingerTypeCreateLine;
lineBtn.userInteractionEnabled = YES;
lineBtn.backgroundColor = [UIColor lightGrayColor];
[self.view addSubview:lineBtn];
UITapGestureRecognizer *tapLine = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(change:)];
[lineBtn addGestureRecognizer:tapLine];
}
– (void)change:(UIGestureRecognizer*)gr
{
// ボタンの色を初期化
[self.view viewWithTag:FingerTypeCreateBall].backgroundColor = [UIColor lightGrayColor];
[self.view viewWithTag:FingerTypeCreateLine].backgroundColor = [UIColor lightGrayColor];
// 選んだボタンを濃くする
type = (FingerType)gr.view.tag;
gr.view.backgroundColor = [UIColor grayColor];
}
// タイマーで時間を進める
– (void)tick:(NSTimer*)sender
{
int32 velocityIterations = 8;
int32 positionIterations = 1;
world->Step(1.0f/60.0f, velocityIterations, positionIterations);
for (b2Body* b = world->GetBodyList(); b; b = b->GetNext())
{
if (b->GetUserData() != NULL)
{
UIView *v = (__bridge UIView *) b->GetUserData();
float x = b->GetPosition().x * PixelToMeterRatio;
float y = self.view.bounds.size.height – b->GetPosition().y * PixelToMeterRatio;
CGPoint newCenter = CGPointMake(x,y);
v.center = newCenter;
v.transform = CGAffineTransformMakeRotation(-b->GetAngle());
}
}
}
// ぼーる
– (void)addBall:(CGPoint)point
{
UIView *ball = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 10, 10)];
ball.center = point;
ball.backgroundColor = [UIColor orangeColor];
ball.layer.cornerRadius = 5.0;
[self.view addSubview:ball];
b2BodyDef bodyDef;
bodyDef.type = b2_dynamicBody;
CGPoint dimensions = CGPointMake(ball.bounds.size.width/PixelToMeterRatio/2.0, ball.bounds.size.height/PixelToMeterRatio/2.0);
bodyDef.position.Set(ball.center.x/PixelToMeterRatio, (460-ball.center.y)/PixelToMeterRatio);
bodyDef.userData = (__bridge void *)ball;
b2Body *body = world->CreateBody(&bodyDef);
b2PolygonShape box;
box.SetAsBox(dimensions.x, dimensions.y);
b2FixtureDef fixtureDef;
fixtureDef.shape = &box;
fixtureDef.density = 10.0f; // 密度
fixtureDef.friction = 0.1f; // 摩擦
fixtureDef.restitution = 0.3f; // 反発
body->CreateFixture(&fixtureDef);
body->SetType(b2_dynamicBody);
}
// ２点を結ぶ線をUIViewで作成する
– (void)addLine
{
float w = hypotf(end.x – start.x, end.y – start.y);
UIView *line = [[UIView alloc] initWithFrame:CGRectMake(0, 0, w, 3)];
line.backgroundColor = [UIColor blackColor];
line.center = CGPointMake(start.x + (end.x – start.x) * 0.5, start.y + (end.y – start.y) * 0.5);
[self.view addSubview:line];
float th = atan2f(end.y – start.y, end.x – start.x);
line.transform = CGAffineTransformMakeRotation(th);
b2BodyDef groundBodyDef;
groundBodyDef.position.Set(0, 0); // bottom-left corner
b2Body* groundBody = world->CreateBody(&groundBodyDef);
b2EdgeShape groundBox;
CGSize screenSize = self.view.bounds.size;
groundBox.Set(b2Vec2(0,0), b2Vec2(screenSize.width/PixelToMeterRatio,0));
groundBody->CreateFixture(&groundBox, 0);
groundBox.Set(b2Vec2(start.x/PixelToMeterRatio, (460 – start.y)/PixelToMeterRatio), b2Vec2(end.x/PixelToMeterRatio, (460 – end.y)/PixelToMeterRatio));
groundBody->CreateFixture(&groundBox, 0);
}
– (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end
Box2d導入メモ
1. Box2Dをプロジェクトに組み込む
Xcodeメニューの File -> Add File
svnでチェックアウトしたなかから、Box2D.hが入ってるフォルダをAdd
2. C++ で書く。Fileの拡張子を変更
Box2dを使うソースの拡張子を mm に
今回は、ViewControler.mm に変更
3. Box2Dを import できるように Search Pathを追加
Build Settings (All) の Search Pathsのなかの Header Search Paths をクリック
Box2Dをおいた場所のパスを入れておく