qtrollip wrote:Jonnycakes, can you say that in English please?
angrydemon wrote:Sorry Jonnycakes, I have absolutely no idea what the heck you're talking about!
Haha sorry about that. Sometimes I get carried away and make absolutely no sense. I can't even use the excuse that it was late at night. Actually, I think I was getting in over my head trying to explain something like that in such a short amount of space.
Let me try to reword the parts that haven't been explained already by others:
Hinge creases are not necessary to understand a CP, but it can help the viewer to see the flap arrangement if you add them in. If you want to draw your CP so that it can be folded flat from the creases shown, you have to draw hinge creases, too. Toshikazu Kawasaki presents some basic rules that a CP must satisfy to fold flat: all crease intersections (points where several creases meet) must have an even number of creases coming together, and the difference between mountain and valley folds at a crease intersection must equal 2. For example, if 4 creases meet at a crease intersection, then with 3 mountain folds and 1 valley fold, that crease intersection would fold flat (3 mountain-1 valley=2). An intersection with only 3 creases would not, no matter what arrangement of valley and mountain folds it used.
As in the case with the rabbit ear that origamimasterjared explained, some hinge creases will not be used when you fold a CP. With the rabbit ear, for example, only 1 hinge crease is needed to fold the rabbit ear flat, while there are 3 possible hinge creases in the rabbit ear.
You need to be careful which hinge creases to add in if you want your CP to fold flat exactly how it is, but I personally add most or all of the hinge creases to my CPs. Hinge creases form the outlines of flaps (look back to the rabbit ear example) and clearly show where each flap lies. I think a CP that uses more hinge creases than necessary to fold flat can be clearer than one that shows less hinge creases(or none).
I tried to be as clear as possible, but this was a rather long-winded response. I find myself using a lot of mathematical language, and that is probably because I learned all of this stuff from reading Lang's
Origami Design Secrets. I suppose I ended up giving a little mini-lesson on CPs

. Good luck with your CP-drawing (and hopefully understanding my post

).