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升级到 cocos2d-iphone 2.0 版后，我在绘制对象的坐标时遇到了问题。据我所知，我已经正确升级了所有模板，但仍然存在问题。例如，在“Learning Cocos2D”一书中（第 10 章 box2D）中，我已经实现了几个简单的方法来首先 createGround 和 createBoxAtLocation。第一个方法是从init调用的，如下：

- (void)createGround {
    CGSize winSize = [[CCDirector sharedDirector] winSize];     

    // Set up the Box2D coordinates that correspond to the four corners of the ground boundary
    float32 margin = 10.0f;
    b2Vec2 lowerLeft = b2Vec2(margin/PTM_RATIO, margin/PTM_RATIO);
    b2Vec2 lowerRight = b2Vec2((winSize.width-margin)/PTM_RATIO, margin/PTM_RATIO);
    b2Vec2 upperRight = b2Vec2((winSize.width-margin)/PTM_RATIO,
                           (winSize.height-margin)/PTM_RATIO);
    b2Vec2 upperLeft = b2Vec2(margin/PTM_RATIO,
                          (winSize.height-margin)/PTM_RATIO);
    // Define the static container body, which will provide the collisions at screen borders.
    b2BodyDef screenBorderDef;
    screenBorderDef.position.Set(0, 0);
    b2Body* screenBorderBody = world->CreateBody(&screenBorderDef);
    b2EdgeShape screenBorderShape;

    // Create fixtures for the four borders (the border shape is re-used)
    screenBorderShape.Set(lowerLeft, lowerRight);
    screenBorderBody->CreateFixture(&screenBorderShape, 0);
    screenBorderShape.Set(lowerRight, upperRight);
    screenBorderBody->CreateFixture(&screenBorderShape, 0);
    screenBorderShape.Set(upperRight, upperLeft);
    screenBorderBody->CreateFixture(&screenBorderShape, 0);
    screenBorderShape.Set(upperLeft, lowerLeft);
    screenBorderBody->CreateFixture(&screenBorderShape, 0);
}

这应该在屏幕边缘周围绘制一个绿色边界，边距为 10 点。但是，我只能看到底部和左侧边缘的绿色边界。上边缘和右边缘分别以屏幕高度和宽度的 2 倍绘制。

在同一个 Box2D 示例中，将在用户触摸屏幕的点绘制一个框。当用户触摸屏幕时，方法 createBoxAtLocation 会调用触摸的位置。触摸位置坐标在 cocos2d 点坐标中，并且在您期望的范围内。下面是 createBoxAtLocation 方法：

- (void)createBoxAtLocation:(CGPoint)location
               withSize:(CGSize)size
{

    // First create a body
    b2BodyDef bodyDef;
    bodyDef.type = b2_dynamicBody;                      // This box is a dynamic body (movement handled by box2d)
    bodyDef.position = b2Vec2(location.x/PTM_RATIO,     // convert the point location to meters location
                          location.y/PTM_RATIO);
    bodyDef.allowSleep = false;
    b2Body *body = world->CreateBody(&bodyDef);

    // Now create one or more fixtures to add to the body.
    // To do this, you must first create a shape. In this case, we are creating a square box
    b2PolygonShape shape;
    shape.SetAsBox(size.width/2/PTM_RATIO, size.height/2/PTM_RATIO);    // SetAsBox takes half dimensions as parameters

    b2FixtureDef fixtureDef;
    fixtureDef.shape = &shape;
    fixtureDef.density = 1.0;           // set density. The higher the number, the heavier it is

    body->CreateFixture(&fixtureDef);
}

例如，如果触摸位置是点坐标 193、190.5（在 iphone 视网膜显示器上），则 createBoxAtLocation 方法将在点坐标 386、381 处绘制一个框，即使 location.x = 193 和 location.y = 190.5。请注意，bodyDef.position 的 box2d 坐标为 3.86、3.81，因为 PTM_RATIO 为 50。

我也可以说，当我运行模拟器并选择 iphone（非视网膜）作为硬件时，框会在正确的位置创建，并且 createGround 在屏幕空间内生成正确的边界。我也可以说代码可以识别所有设备的正确尺寸屏幕（例如 cocos2d 打印出 cocos2d：表面尺寸：iPhone 的 480x320 和 cocos2d：表面尺寸：iPhone 3.5 视网膜的 960x640）。最后，我运行了调试器并深入研究了绘图程序。据我所知和理解，绘图程序知道正确的 box2d 坐标。但是该框只是显示在一个 2X 的坐标上，它应该是视网膜显示器的坐标。

我怀疑 createGround 的问题和 createBoxAtLocation 的问题是相同的。我确信有一个简单的解决方案，但我无法弄清楚。有什么建议么？

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