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Re: Quesa Polyhedrons SOLVED

To: REALbasic NUG <realbasic-nug at lists dot realsoftware dot com>
Subject: Re: Quesa Polyhedrons SOLVED
From: Thomas Moore <tmoore at pomona dot edu>
Date: Sun, 31 Jul 2005 15:06:24 -0700
Delivered-to: realbasic-nug at lists dot realsoftware dot com
References: <F89A5776-385B-4C44-AC65-BF740B35C198 at frontiernet dot net> <003901c594a5$df74dde0$1501010a at johntoshiba> <97B61972-032F-4E03-8A42-DF3BFF6081F5 at pomona dot edu> <2DE337D4-CD01-44C3-819E-3E193951E2DA at chaoticbox dot com>
On Jul 30, 2005, at 5:25 PM, Frank Condello wrote:

There's two ways to do this:

1) Don't share vertexes, and submit normals with your mesh. So instead of 4 vertexes to define the pyramid use 12 (3 per triangle) and assign normals to each equal to the facet normal.

2) Apply a "none" interpolation style to the geometry (with declares).

Thank you very much, Frank: the first method (though it is tedious to load everything up) works just fine. I really appreciate the suggestion!

PS. I wanted to use pyramids for the vector tip because I guessed that an object having only five faces would render more quickly than something more complicated like a cone. Am I correct about this?

Depends - a highly subdivided cone may take more time to render, but performance in Quesa tends to degrad more as the object count goes up rather than the triangle count. So 100 pyramids may actually render at the same speed as 100 cones using 3 times the triangles.

Also, you can create a 3-sided cone using the built-in cone primitive and a subdivision style. Grab my Quesa Wrappers project (here: <http://developer.chaoticbox.com/>) and check the "StylesAndIllumination.rb" example project. It creates a cylinder where you can dynamically alter the mesh resolution with a slider. It works the same way for a cone, and if you use this approach you can allow people to change the resolution at runtime to trade visual quality for performance, or even have the mesh modify itself dynamically depending on the distance from the camera (continuous LOD).

This is a really interesting idea! I had no idea one could do this. Your Quesa Wrappers classes look *very* interesting and useful. I wish that I had known about them earlier before I had so much invested in code! I will look forward to studying them more closely.

Thanks again,

Tom Moore

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