Geodesic Vs Polar
"B. Isherwood" <[email protected]> Tue, 28 May 2013 19:42:41 -0400
| Newsgroups | gmane.comp.graphics.crystalspace.devel |
|---|---|
| Message-ID | <CAMrLf9kCY84MdVJrwF2tfdduo4=xHpLFSTJEd9yN+TE+0R5yRQ@mail.gmail.com> |
Hello Stefano So I will just explain the logistical differences Geodesics: Essentially a geodesic dome or sphere is a structure that is built from equilateral triangles where all the corners are projected onto an outer sphere. So for this project since all the vertices are separated by exactly the same distance and have exactly the same angle of attack all of the cells will even and therefore in theory should remove all distortions. I am going to link a gif from wikipedia so you can see what I mean. http://en.wikipedia.org/wiki/File:G%C3%A9ode_V_3_1.gif The main problem is this form of sphere requires a recursive building procedure and there is no defined equator or dateline, meaning the divisions appear to be less organized Polar Coordinates: Polar coordinates have an LOD issue and that is the farther you are from the poles the more more stretched the cells you are working with are. The main advantage of polar coordinate systems are they are simple to use for less complicated structures such as plain spheres since the appearance. Essentially you can think of a polar sphere as a series of circles drawn 1 after the other rotating around a single point, because the poles of the sphere are closer to the rotational axis the distance between each circle is less than they would be at the equator. This form leaves well to matching up with and XYZ system by replacing it with a phi, radius, theta system, this is the main advantage, since I can map directly from the existing terrain functions with a very small amount of work. However the cost will be stretching at the poles. I am linking an image that illustrates this problem. http://content.answcdn.com/main/content/img/McGrawHill/Encyclopedia/images/CE160600FG0020.gif As you can see the longitudinal lines begin to stretch out as you approach the equator. I am leaning towards developing a geodesic version over the polar version, however it is the difficulty of converting the XYZ of the terrain generators to the geodesic one seems daunting, however I think that I will solve this problem by figuring out how to layout the geodesic sphere as a flat 2D plane finding the relation to the proper XYZ plane. So which system do you think will be preferable? One last thing, when it comes to geometric programming I tend to make a lot of notes, I think it would be easier for me to keep on track if I were to send my notes every couple of days and perhaps you can comment on them and give advice? ------------------------------------------------------------------------------ Introducing AppDynamics Lite, a free troubleshooting tool for Java/.NET Get 100% visibility into your production application - at no cost. Code-level diagnostics for performance bottlenecks with <2% overhead Download for free and get started troubleshooting in minutes. http://p.sf.net/sfu/appdyn_d2d_ap1 _______________________________________________ Crystal-develop mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/crystal-develop