Question

I’m writing a C# game engine for my game, and I’ve hit a problem.

I need to do a XNA.Rectangle drawRectangle for each different type of block.

Blocks are stored in a list of blocks, so the property, to be accessible by draw without casting a lot, must be overriden.

I’ve tried lots of ways of doing it, but none work.

Here’s the current one I’m doing:

Block.cs

protected static Rectangle m_drawRectangle = new Rectangle(0, 0, 32, 32);
public Rectangle drawRectangle
{
    get { return m_drawRectangle; }
}

BlockX.cs

protected static Rectangle m_drawRectangle = new Rectangle(32, 0, 32, 32);

However when creating BlockX and accessing drawRectangle, it still returns 0, 0, 32, 32.

Ideally I could just override the drawRectangle member, however doing this would mean creating a member in every single block class. I only want to adjust m_drawRectangle.

Each block will be created hundreds of times so I don’t want it to be non-static, and it would be silly to do it in the constructor.

Is there any better way other than just putting a static function to initialise static things in every block?

Edit:

So to sum up, my requirements are:

• Minimal extra code in BlockX.cs to override
• Field must stay static
• Preferably not have to override drawRectangle, only m_drawRectangle.
• Not having to create a new rectangle every time the property is accessed

Answer 1

Statics members aren’t called polymorphically – it’s as simple as that. Note that you talk about the property staying static – you don’t have a static property at the moment. You have an instance property, and two static fields.

A couple of options:

• A virtual member which is overridden in each class, even though it doesn’t need any state from the object other than its type
• Pass the rectangle to draw into the constructor of the block, and store it in a field