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Polygon Splitting – For Use With Object Buffer
I’ve been struggling with this for a while now, and it’s been a huge problem. I’m hoping somebody out there has the answer to this, I’ve been unable to find the solution so far.
I have a model that I’ve downloaded, it’s of an airplane. I’m new to c4d, so before diving into modeling I wanted to make sure that c4d works the way I need it to in order to output to after effects.
I’ve created an short animation, and then added an object buffer to my polygon group. I used two lights inside the engines to use with particular for smoke/heat haze in after effects. I created an object buffer for the plane so that it renders a matte pass for compositing in After Effects. It works great, and it does what it’s supposed to do; create an alpha channel for my model so that I can keep it in the foreground within After Effects
The Problem
I need to select part of the polygon and use it as a separate object buffer pass, for a total of two passes. One is for the entire model, and one is for a section of the model (part of the fuselage). The fuselage is one polygon with this model, and I haven’t been able to ‘cut out’ or ‘disconnect’ the part I need a separate object buffer pass for.
Things I’ve tried
I have tried to use ‘disconnect’ under functions while having the section of the fuselage highlighted. This does separate it from the polygon, and I can move it away while retaining the textures. The problem comes when I render the object buffer. Instead of a solid white piece, on both passes the section I disconnected is rendered as black and white triangles, instead of a solid white piece.
How do I cut out this section of the fuselage polygon, simply to use the new section as a separate object buffer pass?I realize this was a long post, but I hope that my question came across clearly enough for somebody kind enough to offer a solution.
Thanks!
-Andrew -
4 Replies
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I’m not sure I understand. In some places it sounds like your model is one polygon and in other places it sounds like a full 3D model.
If it’s the latter, select the polygons you want to separate and then run the Functions>Split command. That will create a separate object composed of just those polygons, but it won’t delete them from the original model. Go ahead and delete them from the original model. Then group both objects under a null and assign a compositing tag to the null, and another one to the object you split off. Create two object buffer passes for those tags and you should be good to go. You’ll have one alpha for the whole plane and another for smaller section you split off.
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Thanks for the quick response Adam.
I don’t think I was explaining myself right in my original post. Imagine I have a tube (a single polygon) and I want to mask off only a section of it (object buffer). But I only want to select a portion of the tube, and assign it a buffer object number.
The part of the plane I am trying to do this to is part of the fuselage, which is one big polygon(model). I tried doing what you suggested, but I’m still getting the black and white triangles on the section of the plane that I’ve split from the polygon.
Does this make more sense?
EDIT: If I have a sphere, and I want to cut out only a 1/4 of it and assign it a buffer object pass, how would I do that?
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Maybe it’s easier to explain this way.
I’d like to select just a portion of the face of a polygon, and give it an object buffer value for export.
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You can only assign an object buffer to an object, which has to consist of at least one polygon, so you would have to use the knife tool, or some other modeling tool(s) to subdivide your one-polygon object.
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