Cut off png

How would I go about drawing half a png for example?

Like so

You would use this.

surface.DrawTexturedRectUV. UV ranges from 0 to 1, so use it like a percentage in a way.

[editline]29th April 2015[/editline]

Or if you are really lazy, you could use this

render.SetScissorRect

surface.DrawTexturedRectUV works for me, Thanks