Subject: Background terrains

From: [email-masked] (Technically Sweet)
Date: Sun, 3 Jan 93 14:32:47 -0800

I've been asked to expound on doing a background terrain alg.
Just shooting off:

Think incrementally.  The viewpoint moves across the landscape,
so you only have to process newly exposed strips at the edges.

If the view angle stays constant, this makes things much easier.

Ground features can obscure other ground features, cast a ray
from each pixel to the height field until you hit.  

Backwards: cast terrain to screen in z-buffer mode from
near part of strip to far part.  Z-buffer in blocks as big
as the height field pixels instead of screen pixels.  Paint
height field averaging across pixels, with neighboring 
height points contributing to a pixel.  Do this pixel by
pixel, adding and removing terrain points as you go across.

As for painting object on top of this, I would attempt this with
a board that has foreground/background bit planes, or with
a video mixer and a separate machine doing the terrain field.

-- 

Lance Norskog
[email-masked]
Data is not information is not knowledge is not wisdom.