### Welcome, Unregistered.

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

 21-Nov-2002, 12:26 #1 Axl Registered   Join Date: Aug 2002 Posts: 4 BSP build and shared vertices I'm trying to build an adequate axis aligned BSP tree for my raytracer that only uses triangles. Usually the stop criteria for the build is when the amount of triangles is less than a number (usually 2 or 3) or when the maximum depth is reached. The problem is with triangles that share verices the build will only stop when reached maximum depth which is very sub-optimal. Usually one vertex is shared by 5 or 6 triangles which is usually higher that you want in a node. The nodes that contains vertices seem impossible to decompose any further. I'm trying to solve this by with either when a node contains one or more vertices recursion stops. Or, if a node contains only one vertex, set split plane at the vertex and look at the other vertices to see what side the triangle is on. Do you have any better way to solve this? Because this is for a raytracer I don't have to care about splitting the triangles.
 21-Nov-2002, 13:55 #2 Saem Senior Member   Join Date: Feb 2002 Posts: 1,532 I don't know much about raytracing, but shared vertices, makes me thinkg of KD-trees. __________________ Regards.
22-Nov-2002, 01:16   #3
Axl
Registered

Join Date: Aug 2002
Posts: 4

Quote:
 Originally Posted by Saem I don't know much about raytracing, but shared vertices, makes me thinkg of KD-trees.
An axis aligned BSP is basically a KD-tree, just a another name for it. Some called it BSP some call it KD-tree.

 23-Nov-2002, 07:13 #4 Saem Senior Member   Join Date: Feb 2002 Posts: 1,532 Out of curiosity, why is 5 to 6 polys considered too many? __________________ Regards.
23-Nov-2002, 15:03   #5
Axl
Registered

Join Date: Aug 2002
Posts: 4

Quote:
 Originally Posted by Saem Out of curiosity, why is 5 to 6 polys considered too many?
I think I have set the number a little too low. The reason I used 2 or 3 is because I got better performance for a few objects. On a second thought I think I have to raise that threshold a bit.

 25-Nov-2002, 09:34 #6 Saem Senior Member   Join Date: Feb 2002 Posts: 1,532 AFAICT, I don't think restricting the number of polygons per node is really necessary. One can only have so many polygons that have a common vertex divider. __________________ Regards.

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home News Forums     Beyond3D News         Press Releases         Beyond3D Articles Core Forums     3D Architectures & Chips         3D Beginner's Questions     3D Technology & Algorithms         3D Programming & Tools     3D Hardware, Software & Output Devices         Video Technology, Displays, & HTPC     3D & Semiconductor Industry     GPGPU Technology & Programming Embedded 3D Forums     Console Forum         Console Technology         Console Games             PC Games     Handheld Gaming     Handheld Technology     CellPerformance@B3D PC Forums     Hardware & Software Talk         Politics & Ethics of Technology         Unix, Mac, & BSD (3D)     Processor & Chipset Technology     Purchase Decisions Help     PC Games         Console Games Site Forums     General Discussion     Folding For Beyond3D Team #32377     Industry Jobs     Site Feedback Beyond3D Hall of Fame     Pre-release GPU Speculation     General 3D Technology     Consoles     Other

All times are GMT +1. The time now is 20:12.

 -- vB3D -- vBulletin Default Style Contact Us - Beyond3D - Archive - Top