如何在Cocos2D物理世界中定义不规则形状的精灵

Question

我想用26个英文字符创建精灵，让它们在框架内相互碰撞（例如，如下图中的X和E）。

创建26个形状的推荐方法是什么？

Answer 1

你为字母表的每个字符拍摄26张图像精灵（优先选择.png图像），然后定义每个角色的固定点，（借助于vertexHelper参考THIS链接了解更多关于 vertextHelper ），就像“我”一样：

 //OBSTACLE_Adjustments
    {
        CCSprite *sprite = [CCSprite spriteWithFile:@"I.png"];
        sprite.position = ccp(96,96);
        sprite.tag = 2;
        [self addChild:sprite];

        //SHAPE 1:
        {
            b2BodyDef bodyDefinition;
            bodyDefinition.type = b2_dynamicBody;
            bodyDefinition.position.Set(96/PTM_RATIO, 96/PTM_RATIO);
            bodyDefinition.userData = sprite;

            obstacle_AdjustmentsBody= world->CreateBody(&bodyDefinition);

            // Create body shape
            b2PolygonShape bodyShape;
            //row 1, col 1
            int num = 4;
            b2Vec2 verts[] = {
                b2Vec2(6.5f / PTM_RATIO, -25.0f / PTM_RATIO),
                b2Vec2(6.5f / PTM_RATIO, 27.0f / PTM_RATIO),
                b2Vec2(-7.5f / PTM_RATIO, 27.0f / PTM_RATIO),
                b2Vec2(-7.5f / PTM_RATIO, -26.0f / PTM_RATIO)
            };

            bodyShape.Set(verts, num);

            // Create shape definition and add to body
            b2FixtureDef bodyFixtureDefinition;
            bodyFixtureDefinition.shape = &bodyShape;
            bodyFixtureDefinition.density = 100.0f;
            bodyFixtureDefinition.friction = 0.01f;
            bodyFixtureDefinition.restitution = 0.50f;              
            obstacle_AdjustmentsFixture=obstacle_AdjustmentsBody->CreateFixture(&bodyFixtureDefinition);            
        }
}

此处obstacle_AdjustmentsBody为b2Body，obstacle_AdjustmentsFixture为b2Fixture。

这里是X的形状：

 //OBSTACLE_ALPHABATE
    {
        CCSprite *sprite = [CCSprite spriteWithFile:@"X.png"];
        sprite.position = ccp(96,96);
        sprite.tag = 2;
        [self addChild:sprite];

        //SHAPE FIRST LEG OF X:
        {
            b2BodyDef bodyDefinition;
            bodyDefinition.type = b2_dynamicBody;
            bodyDefinition.position.Set(96/PTM_RATIO, 96/PTM_RATIO);
            bodyDefinition.userData = sprite;

            obstacle_AdjustmentsBody= world->CreateBody(&bodyDefinition);

            // Create body shape
            b2PolygonShape bodyShape;
            //row 1, col 1
            int num = 4;
            b2Vec2 verts[] = {
                b2Vec2(108.0f / PTM_RATIO, -71.5f / PTM_RATIO),
                b2Vec2(56.0f / PTM_RATIO, 2.5f / PTM_RATIO),
                b2Vec2(47.0f / PTM_RATIO, -3.5f / PTM_RATIO),
                b2Vec2(96.0f / PTM_RATIO, -75.5f / PTM_RATIO)
            };

            bodyShape.Set(verts, num);

            // Create shape definition and add to body
            b2FixtureDef bodyFixtureDefinition;
            bodyFixtureDefinition.shape = &bodyShape;
            bodyFixtureDefinition.density = 100.0f;
            bodyFixtureDefinition.friction = 0.01f;
            bodyFixtureDefinition.restitution = 0.50f;              
            obstacle_AdjustmentsFixture=obstacle_AdjustmentsBody->CreateFixture(&bodyFixtureDefinition);            
        }

        //SHAPE SECOND LEG OF X:
        {
            b2BodyDef bodyDefinition;
            bodyDefinition.type = b2_dynamicBody;
            bodyDefinition.position.Set(96/PTM_RATIO, 96/PTM_RATIO);
            bodyDefinition.userData = sprite;

            obstacle_AdjustmentsBody= world->CreateBody(&bodyDefinition);

            // Create body shape
            b2PolygonShape bodyShape;
            //row 1, col 1
            int num = 4;
            b2Vec2 verts[] = {
                b2Vec2(117.0f / PTM_RATIO, -4.5f / PTM_RATIO),
                b2Vec2(113.0f / PTM_RATIO, -1.5f / PTM_RATIO),
                b2Vec2(54.0f / PTM_RATIO, -51.5f / PTM_RATIO),
                b2Vec2(61.0f / PTM_RATIO, -56.5f / PTM_RATIO)
            };

            bodyShape.Set(verts, num);

            // Create shape definition and add to body
            b2FixtureDef bodyFixtureDefinition;
            bodyFixtureDefinition.shape = &bodyShape;
            bodyFixtureDefinition.density = 100.0f;
            bodyFixtureDefinition.friction = 0.01f;
            bodyFixtureDefinition.restitution = 0.50f;              
            obstacle_AdjustmentsFixture=obstacle_AdjustmentsBody->CreateFixture(&bodyFixtureDefinition);            
        }
}