View Full Version : objects intersection problem

06 June 2009, 04:54 AM
Hi all,

I'm modeling a boat so I have a hull (which has some thickness so it's not just one surface) and water around it.

The problem is that I have water inside the hull and I'm looking for the easiest way to keep it outside.

I know I can make a boolean difference between water and the hull and make a water with an appropriate depression in it but it's not convenient for many reasons (the boolean operation gives a complicated shape as the hull is a 3D mesh; I have double surfaces where water meets the hull and rendering goes weird; I need to change the hull's shape and I don't want to change water each time; when I add noise to the water surface it goes inside the hull and so on..)

So I will appreciate it if anyone will suggest any other/better way to do it.


06 June 2009, 09:31 AM
The boolean is a good approach... but given that your boat hull has a thickness you should use that to hide the join!

rather than using the boat hull to intersect try using another simpler object set in the middle of that thickness and set it to not render ( un-check the "render" icon next to this object in the outliner) but still use it for the boolean.

Are you using the boolean modifier? that way it can be dynamic, frame by frame... so will give less problems when animating.

Other approaches are:

1)to use a mask texture (bitmap of the boat hull shape)that uses map input of "object"... and set it to alpha the water material......can get messy, I'd use an empty rather than the boat itself and try point and orient constraining it to the hull, but use "scale" to tweak it to shape...

...nicer in my opinion,,,, render the water and the boat as separate render layers and build a matte somehow to combine them... probably I'd use another model of the boat that doesn't have the insides carved out and rendeing a pass of this object and the water.......The "index" pass should give you a nice matte in this case.

you could put the "compositor" version of the boat on another layer and either make it a child of your boat or point and orient constrain it to your boat.

06 June 2009, 11:09 AM
Thanks! I need time to digest it though

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06 June 2009, 11:09 AM
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