# Infinitely long 3D model

Let's say that I want to render something like Dimmadome's hat, a hat which has the height of infinity.

A quick answer to this would be to place the top side of the hat high enough for the crown(cylinder) to be cropped(like y=9999999...) half way in the view. I don't like this idea. So what I came up with is using IEEE 754 infinity in vertices.

(-0.5, INF, -0.5)
(0.5, INF, -0.5)
(0.5, INF, 0.5)
(-0.5, INF, 0.5)


(assuming the crown is a cube)

The problem is that after multiplying with the transform matrix, the vertices end up being all (INF, INF, INF), making them unrenderable. I just wrote this to give you an idea.

Is there any technique that can be used to achieve this? rather than using huge number? I wonder how they implemented this.

• Perhaps you could try using homogeneous coordinates with w=0. It's sometimes used to create shadow volumes that extend off to "infinity". – Simon F Sep 3 '18 at 13:23
• In episode "Mission Responsible they mention: "... 80-story hat storage building" - while on other pages they mention regular size and "infinitely tall". – Rob Sep 4 '18 at 21:53
• What if you make the hat normal size but then use vertex shaders to always extend it so that it is barely larger than the screen? – piegames Sep 15 '18 at 9:54