Author Topic: To Z-Buffer or not to Z-Buffer?  (Read 466 times)

Offline Raubvogel

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To Z-Buffer or not to Z-Buffer?
« on: March 18, 2001, 03:26:00 PM »
That is the question   Just installed new mobo and 1Ghz T-Bird, so I decided to play around with some settings. What exactly is Z-Buffering? If I check it, it cuts my frame rate almost in half. Also, whats the deal with triple buffering?

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Raubvogel
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Offline Skuzzy

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To Z-Buffer or not to Z-Buffer?
« Reply #1 on: March 19, 2001, 08:14:00 AM »
I am not sure how HTC uses Z-buffer, but it basically is a function of controlling the level of detail in the distance.
The Z-buffer depth (8,16,24,32 8 bit stencil) all refer to the largest number for calculating the LOD for any given distance, relative to your camera position in the game.
The lower the number of bits, the less detail is displayed as objects move further away from you.
Generally speaking, the higher Z-buffer depth you use, the lower your frame rates will be, as the video card must do more calculations for each given texel is needs to render.  The tradeoff is the detail level of all images that are in the distance.  Distance is all relative and pretty much up to the software that is running on your computer.
Again, I do not know how HTC/AH uses the z-buffer, but that is generally what it is.

Triple buffering: Modern day video cards have 2 frame buffers on-board.  One is the frame that is currently being sent to the monitor, the other is the one that the video card is currently rendering and will be displayed next once the other frame is done (this action depends on how v-sync is setup) done.
With triple-buffering, another frame is created in system memory, which is comprised of all the unrendered objects for that frame.  This allows software to prepare a frame of data to blast to the video card once the video card has a free frame buffer.
Generally speaking, for slower video cards it helps increase performance, as the software/CPU is no longer waiting for the video card to clear a frame buffer for the next frame draw.
Faster video cards, particularly the ones that are faster than the CPU can take a frame hit when triple buffering is enabled, as the CPU is spinning its wheels preparing a frame, instead of firing off the data to the card.
Again, I do not know how HTC/AH handle this, as there are many ways it could be handled.
This is usually an option you need to try, before determining which (on or off) gives the best display performance.  Performance, in this sense is regarding the frame draws, not the frame rate (i.e. is panning smooth? is movement of images smooth?).

Hope that helps.


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Offline SKurj

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To Z-Buffer or not to Z-Buffer?
« Reply #2 on: March 19, 2001, 11:20:00 AM »
Z-Buffer in aces is for 3dglasses I believe, so don't use it


SKurj