c++ - 如何使用Box2D分配器？

这里有两个问题。首先，如果我需要在b2BlockAllocator之前创建Clone，然后在克隆后删除(哪里？)？ Xcode分析工具未显示C++泄漏...

b2FixtureDef fixd = fix->fixture;
const b2Shape *shape = fixd.shape;
if(shape->GetType()== b2Shape::e_polygon && flip)
{
    b2PolygonShape* ps = (b2PolygonShape*)shape->Clone(new b2BlockAllocator());
    for(int i=0;i<ps->m_vertexCount;i++)
    {
        ps->m_vertices[i].x *= -1;
        ps->m_vertices[i].y *= -1;
    }

    ps->Set(&ps->m_vertices[0], ps->m_vertexCount);
    body->CreateFixture(ps, 1.0f);
...

在这段代码中，我将缓存的形状对象，克隆它，修改顶点，设置为计算法线并将其分配给主体。问题-这合法吗？

更新:

-(void) addFixturesToBody:(b2Body*)body forShapeName:(NSString*)shapeName flip:(BOOL)flip
{
    BodyDef *so = [shapeObjects_ objectForKey:shapeName];
    assert(so);

    FixtureDef *fix = so->fixtures;
    while(fix)
    {
        b2FixtureDef fixd = fix->fixture;
        const b2Shape *shape = fixd.shape;
        if(shape->GetType()== b2Shape::e_polygon && flip)
        {
            b2BlockAllocator allocator;
            b2PolygonShape* ps = (b2PolygonShape*)shape->Clone(&allocator);
            for(int i=0;i<ps->m_vertexCount;i++)
            {
                ps->m_vertices[i].x *= -1;
                ps->m_vertices[i].y *= -1;
            }

            ps->Set(&ps->m_vertices[0], ps->m_vertexCount);
            body->CreateFixture(ps, 1.0f);
        }
        else
        {
            NSLog(@"noflip...%@", shapeName);
            body->CreateFixture(&fix->fixture);
        }
        fix = fix->next;
    }
}

最佳答案

我试图找到类似答案时晚了4年才回复。似乎很少有人在Box2D方面付出更多的努力。

因此，您肯定在泄漏，因为new b2BlockAllocator不会在任何地方被您或克隆函数删除。

只需创建一个本地b2BlockAllocator，以便在超出范围时将其销毁。就是这样。

    b2BlockAllocator cloneHelper;
    b2PolygonShape* ps = (b2PolygonShape*)shape->Clone(&cloneHelper);