确定用于渲染文本的字符的y位置

I have been working on my own bitmap font renderer and while I believe I may have the character spacing correctly, I am not sure how I can determine the the y placement of the character. For example, if the letter 'a' had a y placement of 0, then what would '*' or ',' have? I have been using the winapi function I have been working on my own bitmap font rende