描述形状的尺寸。
仅用于原始形状：球体、胶囊体、盒体。
• Sphere: size is the dimensions of a box enclosing the sphere (i.e., x, y, and z are all equal to the diameter).
• Box: size is the dimensions of the box.
• Capsule: size is the dimensions of a box enclosing the capsule (i.e., x and z are equal to the diameter of the capsule and y is the height).