DTS Rendering VS DIF Rendering
by Cinder Games · in Artist Corner · 05/26/2005 (9:57 pm) · 6 replies
OK, i wanna first say i plan for the most part to use DTS objects for building and just about everything else for a few reasons. I want to know more about how the engine handles them. I thought i read that regardless of how much of the DTS object is visible, it has to do a visibility check for every poly in that DTS object.
Is that true? For DTS objects with no transformation VS a DIF that's the exact same poly structure..... anyone have any comparision of performance? Also.... i was thinking for more complicated structures.... or even levels... instead of using on large DTS file, just use several broken up dts files and just place them next to eachother to reduce the strain on the engine if it needs to do all sorts of visibility checks. I plan on a 3rd person 3/4 birds eye view for the most part so draw distance is not going to be a factor for the most part..... anyone able to shed some light on my questions or point me in the right way? Hope it makes sense.
Is that true? For DTS objects with no transformation VS a DIF that's the exact same poly structure..... anyone have any comparision of performance? Also.... i was thinking for more complicated structures.... or even levels... instead of using on large DTS file, just use several broken up dts files and just place them next to eachother to reduce the strain on the engine if it needs to do all sorts of visibility checks. I plan on a 3rd person 3/4 birds eye view for the most part so draw distance is not going to be a factor for the most part..... anyone able to shed some light on my questions or point me in the right way? Hope it makes sense.
#2
05/26/2005 (11:13 pm)
That's true... portals would definately help in the calculation process... but DTS can have LOD. i'm sure that's not a much of a performance boost though. 
#3
No
Portals are the main advantage that dif's have over dts's with regards to rendering speed. Both have LOD. Dts's can get very slow if they are animated. No animations on a dif so can't really compare there. Dts's also allow blended alpha textures which can get slow if overused.
Rendering-wise there isn't a huge performance gain either way aside from being able to portal off sections and even that isn't that big a deal on modern video cards.
Now lighting and physics...there are *huge* differences with those.
FAQ: What is the difference between .dif and .dts shapes?
05/26/2005 (11:29 pm)
Quote:
I thought i read that regardless of how much of the DTS object is visible, it has to do a visibility check for every poly in that DTS object. Is that true?
No
Portals are the main advantage that dif's have over dts's with regards to rendering speed. Both have LOD. Dts's can get very slow if they are animated. No animations on a dif so can't really compare there. Dts's also allow blended alpha textures which can get slow if overused.
Rendering-wise there isn't a huge performance gain either way aside from being able to portal off sections and even that isn't that big a deal on modern video cards.
Now lighting and physics...there are *huge* differences with those.
FAQ: What is the difference between .dif and .dts shapes?
#4
05/26/2005 (11:41 pm)
I plan on having my DTS objects just serve for mostly static items walls and what not. I was mainly concerend with how slow it'd be cause i "thought" i remember reading somehting about visibility checks for the whole DTS object even it's its partially viewable. 
#5
I'm doing something similar to you and my old Geforce 3 was doing fine with 100,000 polys and no occlusion or LOD in the scene at all.
the things you have to consider is whether you mind losing some of the lighting benefits that BSP geometry offer. With DTS I think the lighting pack can aleviate a lot of those lighting and shadow problems, but to what extent, I'm not sure. Thats something I'm going to have to look into in the not too distant future.
I believe you can do a lot with the work methology your talking about, but there's a good chance that you will have to dig into the source somewhat if you want to get optimize the performance.
The birds eye view should make things a lot simpler. I worked on a baldurs gate style 3d RPG a while back using a tile system that had the entire world built of interchangeable tiles with unique areas of interest.
The same tiles were all instances of one another, and each was frustrum culled by their local bounding box so you only drew the chunks that were visible. (tiles were made up 1, 2, or 4 meter square geometry chunks, was surprising how much varierty you could get.
One nice thing is you don't need a lot of detailed collsions in this type of game, and no ceiling if its a birds eye view.
Couple of examples I found on my HD of tiled birds eye type stuff.
Polycount wise these kinds of tiles would typicaly draw 20,000 to 70,000 polys on screen at a time.
If you have the tools and your not afraid to try it, you could try DTS for visuals and Dif for collisions, collisions don't need to be more than really simple smooth walled shapes, since you want your units to move around without getting caught on the details, might be a lot faster, but a bit more fiddly.
05/26/2005 (11:53 pm)
I'm not sure how big a problem its going to be on modern computers. someone had over 100,000 polys of animated characters in their game (obviously DTS, and it ran fine on their system just with the characters alone)I'm doing something similar to you and my old Geforce 3 was doing fine with 100,000 polys and no occlusion or LOD in the scene at all.
the things you have to consider is whether you mind losing some of the lighting benefits that BSP geometry offer. With DTS I think the lighting pack can aleviate a lot of those lighting and shadow problems, but to what extent, I'm not sure. Thats something I'm going to have to look into in the not too distant future.
I believe you can do a lot with the work methology your talking about, but there's a good chance that you will have to dig into the source somewhat if you want to get optimize the performance.
The birds eye view should make things a lot simpler. I worked on a baldurs gate style 3d RPG a while back using a tile system that had the entire world built of interchangeable tiles with unique areas of interest.
The same tiles were all instances of one another, and each was frustrum culled by their local bounding box so you only drew the chunks that were visible. (tiles were made up 1, 2, or 4 meter square geometry chunks, was surprising how much varierty you could get.
One nice thing is you don't need a lot of detailed collsions in this type of game, and no ceiling if its a birds eye view.
Couple of examples I found on my HD of tiled birds eye type stuff.
Polycount wise these kinds of tiles would typicaly draw 20,000 to 70,000 polys on screen at a time.
If you have the tools and your not afraid to try it, you could try DTS for visuals and Dif for collisions, collisions don't need to be more than really simple smooth walled shapes, since you want your units to move around without getting caught on the details, might be a lot faster, but a bit more fiddly.
#6
05/26/2005 (11:57 pm)
Yeah, looks alot like what i'm planning. RPG. so nothing needs to be too complex as far as lighting and all that. I guess i'll go full steam ahead on the project using DTS until i hit snags. 
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