can you delete polys or select polys based on alpha or mask?

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  11 November 2004
can you delete polys or select polys based on alpha or mask?

can you delete polys or select polys based on alpha or mask?
  11 November 2004
Arrow Everything you wanted to know and more. :)


While your model is in Edit mode, you can press Tool>Masking>Alp to apply the currently-selected alpha as a mask. The quality of what you get will depend on the resolution of the mesh (In other words, the more polygons your mesh has, the less jaggy the edges will be.) , or how well the alpha follows the flow of the mesh. The alpha is applied based upon the model's UV coordinates. This means that you can even use Projection Master to paint a black and white texture that shows your selection area (letting PM handle the process of unwrapping it), press Texture>Make Alpha to convert it to an alpha, and then use the steps above to apply it as a mask. Very handy, under the right circumstances!

Once the mask is created from the alpha, you can now press Tool>Masking>HidePt to hide the unmasked portions. If you are working with a parametric object, that's as far as you can go, but if you have a polymesh then you can press Tool>Geometry>Delete Hidden to remove those polygons completely. Feel free to clear the mask.

Another way that you can work is to paint your mask by holding down the Ctrl/Cmd key and painting on your model. You can then use the steps above to hide and delete the unmasked portions.

One really cool thing here is that you can use alphas as a way to store polygon selections. Let's say that you use ZBrush 2's partial mesh visibility controls to hide all but part of the mesh and you know that you'll want to return to this particular selection at a later time. Simply press Ctrl/Cmd and click anywhere on the empty canvas. The visible portions of the model will be masked. Now press Tool>Masking>Create Alpha to convert the mask to an alpha, which you can recall later using the Tool>Masking>Alp button. You can use this easy technique to quickly build up a set of saved selections and swap between them at will. If you save the alpha after creating it, the interface will then show the name of the selection, too, making it easy to find the one that you need later.

Hope that helps!
  11 November 2004
Oh Man, that's excellent! I never knew any of that stuff. Thanks Aurick!!

Galen Beals
CG Animation
  01 January 2006
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