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Jappie

Jerky motion in terrain rendering & Rendering techniques

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Hi ppl, I actually have two questions, so here goes: 1) When drawing a landscape I created (some coords from a heightmap crammed into glVertex3f) completely (no viewport culling), and then moving around using glTranslatef, I get smooth animation. But as soon as I add viewport culling, ie. draw only a selected area from that landscape, and the move around, the motion''s all jerky. What exactly is the cause of this, and how can I fix this? I know I came across this subject somewhere... Anyway... 2) What are the big advantages to all those terrain rendering algorithms like quadtrees, octrees, bsp''s etc. Is it the ability to add LOD more easily? Why not just render from a heightmap array? Tnx for any help. ----------------------------- Jappie BabJap Productions "There''s no such things as bugs; they''re just unintentional extra features"

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Guest Anonymous Poster
Your second question basically answers your first.

Turning on viewport culling is in effect turning on
a bunch of math to figure out if you want to draw a given
piece or not.

Octrees, quadtrees and the like speed up this process
by breaking up your "world" into a bunch of pieces that
can be "tossed" out of the current frames render a lot
faster than checking each individual polygon or subojbect.

LODs are for when you are too far away from an object
that uses a lot of polygons so far away that you really cant
tell the difference between the 1000 polygon model and the
50 polygon model. or the difference between the large 256x256
full 32bit textures and the cooresponding 4bit paletted 8x8s.

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Aye, seems logical, but still...

Take a look at these landscapes if you will. No quadtrees or similar algorithms used here, just a set of coordinates of the camera viewpoint. The frustrum is placed around these coords, and a simple for-loop renders all elements inside this bounding box. No checking to see whether elements are inside the frustrum or whatever. My prog works in a similar way, ''tough I don''t see any jerky motion in these samples...

-----------------------------
Jappie
BabJap Productions

"There''s no such things as bugs; they''re just unintentional extra features"

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Guest Anonymous Poster
Got me.

Are you moving your camera?

Bad camera movement, ie not interpolated in some way, can
easily cause jerkyness or pops.




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If you installed directx in debug mode, set it to release mode, it will greatly improve your framerate and get rid of that jerky problem (atleast it did for me).

Possibility

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