Newbie question: best way to fill in 45 degree angle that snaps to object?
It's a totally newbie question-but I'm trying to figure out the best way to do this. I have this:
and I want to do this:

Currently the best way I found is to use a polygon lasso tool and hold down shift to get the first 45 degree angle and then fill with the paint bucket. The problem is that the lasso doesn't snap right to the point, so if I want to do it right I need to zoom way in and manually select. Is there a way to get it to snap to the point and still let me quickly do a 45 degree thing to fill? How would you handle this? Thank you!

