Subject: Re: a light swell
From: [email-masked] (Justin Barrett)
To: [email-masked]
Date: Tue, 24 Oct 1995 16:25:00 GMT

On 23 Oct 95, [email-masked] spoke up and said:

Mi> Interestingly, a variation of your theme is just what I started out
Mi> with--but I couldn't get any texture movement in the Y direction. I was
Mi> using a Planar Image as a Displacement Map, and it simply would not move
Mi> up or down in the y-direction, World Coordinates or not, size or not,
Mi> center or not.

If you had it mapped on the Y axis, this is why you couldn't get any
visible change with a Y velocity.  Planar maps have no "depth", whereas
procedurals do.  The Fractal procedurals change patterns in 3D space in
all directions, but planar maps only do so in two directions...the two
that are unselected when planar mapping.

For example, if you mapped your image as a displacement map in the Y axis
(I'm assuming this is the case), then giving it X and Z velocities would
shift the position of the map in the X and Z directions, and eventually you
would see the map repeating, or tiling.  But movement in the Y axis does
nothing, as there is no depth to a 2D image map.

If we could create 3D paintings and map them, then it would work, but it
would take a huge amount of memory since the "image" would have a 3
dimensional resolution.  Take the amount of memory for a 2D map, and
multiply it by the pixel "depth" you want.  An "image" that's 752 wide by
480 high by 20 deep would be 20 times the size of a normal 752x480 image.
If an average image this size is 700K, a 752x480x20 "image" would take
14MEGS of memory!  :-)

Another way to get an image to change over time is to use color cycling. 
It's harder to get a predictable pattern this way, but it works.

Just some food for thought....

         Justin Barrett - [email-masked] - 1:350/401
    Free Spirit Productions   -   Northland Cable   -   Peninsula College

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