如何用Cocos2d-iPhone绘制一条线

在Cocos2d-iPhone中，要绘制一条线，可以使用CCDrawNode类。CCDrawNode类提供了一系列方法来绘制各种形状，包括绘制线条。以下是一个简单的示例，说明如何使用CCDrawNode类绘制一条线：

首先，导入Cocos2d-iPhone框架：

#import "cocos2d.h"

创建一个CCDrawNode对象：

CCDrawNode *drawNode = [CCDrawNode node];

使用CCDrawNode的drawLineFrom:to:withColor:方法绘制一条线：

CGPoint startPoint = CGPointMake(50, 50);
CGPoint endPoint = CGPointMake(200, 200);
ccColor4F lineColor = ccc4f(1, 0, 0, 1); // 红色
[drawNode drawLineFrom:startPoint to:endPoint withColor:lineColor];

将CCDrawNode对象添加到场景中：

[self addChild:drawNode];

完整的代码示例如下：

#import "cocos2d.h"

@interface DrawLineLayer : CCLayer
@end

@implementation DrawLineLayer

-(id) init
{
    if( (self=[super init])) {
        CCDrawNode *drawNode = [CCDrawNode node];
        
        CGPoint startPoint = CGPointMake(50, 50);
        CGPoint endPoint = CGPointMake(200, 200);
        ccColor4F lineColor = ccc4f(1, 0, 0, 1); // 红色
        [drawNode drawLineFrom:startPoint to:endPoint withColor:lineColor];
        
        [self addChild:drawNode];
    }
    return self;
}

@end

@implementation AppController

-(void) applicationDidFinishLaunching:(UIApplication*)application
{
    CCDirector *director = [CCDirector sharedDirector];
    [director setDisplayStats:YES];
    [director setAnimationInterval:1.0/60];
    [director setView:[[CCGLView alloc] initWithFrame:[[UIScreen mainScreen] bounds]]];
    [director setDeviceOrientation:kCCDeviceOrientationPortrait];
    [director pushScene: [DrawLineLayer scene]];
    [director runWithScene:[DrawLineLayer scene]];
}

@end

这个示例将在屏幕上绘制一条从(50, 50)到(200, 200)的红色线条。你可以根据需要修改线条的颜色和位置。