将多个精灵作为一个旋转（围绕同一原点）

我有形成 T 形状的精灵数组，我想围绕同一原点旋转它们，在我的例子中是 box2D 主体原点，如下所示：

我的形状在矩阵中定义如下：

int array[][]= {{0,1,1,1,0},
                     {0,0,1,0,0},
                     {0,0,1,0,0},
                     {0,0,0,0,0},
                     {0,0,0,0,0}};

这就是我创建身体的方式：

public void setBody(int[][] blocks){
        BodyDef def = new BodyDef();
        def.type = BodyType.DynamicBody;
        def.position.set(new Vector2(0 * WORLD_TO_BOX, 0 * WORLD_TO_BOX));
        Body body = world.createBody(def);
        body.setTransform(130*WORLD_TO_BOX, 200*WORLD_TO_BOX, -90*MathUtils.degreesToRadians);
        for (int x = 0; x < 5; x++) { // HARDCODED 5
            for (int y = 0; y < 5; y++) { // HARDCODED 5
                if(blocks[x][y] == 1){
                    PolygonShape poly = new PolygonShape();
                    Vector2 v = new Vector2((x*size/BOX_TO_WORLD),(y*size/BOX_TO_WORLD));
                    poly.setAsBox(size/2 * WORLD_TO_BOX, size/2 * WORLD_TO_BOX, v, 0);
                    Sprite sprite = new Sprite(new Texture(Gdx.files.internal("data/block.png")));
                    sprite.setSize(size, size);
                    sprites.add(sprite);
                    orig.add(v);
                    body.createFixture(poly, 1);
                    poly.dispose();
                }
            }
        }
        this.body = body;
    }

这是我的渲染方法：

public void draw(SpriteBatch batch){
        for (int i = 0;i< this.body.getFixtureList().size;i++) {
            Vector2 pos = this.body.getFixtureList().get(i).getBody().getPosition();
            Sprite sprite = sprites.get(i);
            sprite.setOrigin(this.body.getWorldCenter().x,this.body.getWorldCenter().y);
            sprite.setPosition(pos.x*BOX_TO_WORLD+orig.get(i).x*32-16, pos.y*BOX_TO_WORLD+orig.get(i).y*32-16);
            sprite.setRotation(this.body.getAngle()*MathUtils.radiansToDegrees);
            sprite.draw(batch);
        }
    }

正如您在图中的“右侧”示例中所看到的，精灵的位置取决于身体的角度，而您没有考虑到这一点。

b2Vec2 pos = ...; // center of the sprite relative to body (local coords)
float ang = ...;  // angle of the sprite relative to body (probably zero)

//need to rotate image local center by body angle
b2Rot rot( body->GetAngle() );
pos = b2Mul(rot, pos) + body->GetPosition();
ang += -body->GetAngle();

sprite.setRotation( ang * RADTODEG ); // RADTODEG = 57.295779513082320876f
sprite.setPosition( PTM * pos.x,  PTM * -pos.y);

在此之前，我还做过以下工作：

sf::FloatRect rect = sprite.getLocalBounds();
sprite.setOrigin( 0.5 * rect.width, 0.5 * rect.height );