Ahh, sounds close to what I was wanting to do... geesh, ya didn't have to
include the source but it's *highly* appreciated!

Scott
----- Original Message -----
From: "David Yazel" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, April 25, 2002 6:31 AM
Subject: Re: [JAVA3D] Need a solution for road/path "decals" on terrain.


> We are doing roads and paths by baking them into the ground textures.  It
> sounds like this won't be possible for you if you want it all downloadable
> on the fly.  We do have another version for places where we want super
high
> density roads / paths over terrain.  I am attaching the relevent code.
You
> won't be able to compile it since it references a lot of code I am not
> including.  Check out getGeometry(). and work backwards from there.  The
> trick is to build the path to a sufficient density that it can mold itself
> to work over the terrain, and then use the z polygon offset to deal with
any
> tiny mistakes.  This algorithm takes a series of path points, builds a
> spline, then builds geometry to flow along the path according to a density
> you define.
>
> David Yazel
> http://www.magicosm.net
>
> ----- Original Message -----
> From: "Scott" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Thursday, April 25, 2002 1:02 AM
> Subject: [JAVA3D] Need a solution for road/path "decals" on terrain.
>
>
> I've been scratching my head over this one for weeks now.
>
> I want to be able to specify "roads" or "paths" in my 3D engine with a
> series of 2D lines.  That would give me the flexibility to have roads any
> any angle, any direction, and any number/combination of intersections.
>
> There's two ways I see of doing it.
>
> First, I would start with a quad that would represent the section of road,
> and it would be "dropped" down onto the terrain.  Of course, the quad
would
> need to be broken up into as many polys neccessary to follow the shape of
> the terrain, and then these polys would be rendered as part of an ordered
> group on top of the terrain, and/or as a decal texture.
>
> Second method that I'm sure would be the obvious response, would be to
> rotate the U/V for the road  texture to whatever angle is needed, and do
> another texture pass on my polys.  The problem I see with this is I don't
> want an entire terrain "block"  (a simple 4x4 mesh) handled with two
texture
> stages for performance reasons, and second, roads/paths would be created
> separately from the terrain heightmap, and I won't know when I'm creating
> the terrain mesh if there's a road there or not.  Also, if there's an
> intersection of 2 or more roads, each would require an additional texture
> stage.
>
> Seems to me that an extra 30-40 polygons in a "modelled" road would be
> insignificant, performance-wise, compared to getting into multiple texture
> passes (and I do want to add a detail texture pass later, so we'd be up to
3
> passes).  Early tests I've done with multitexturing hasn't resulted in
very
> good performance on decent 3D hardware (1.8GHz CPU, GeForce2 and better).
>
> FYI, the terrain is created completely on-the-fly as height data is
> delivered from the server.  No pre-created geometry, or this would be a
> little easier.
>
> Seems like there has to be a simpler solution for this sort of thing, not
> much different than applying pre-calc'd  lightmaps or shadowmaps or decals
> like bullet holes in walls (ala Q3, Half-Life, etc).  The obvious low-end
> solution is a series of say 16 (or more) textures representing various
> combinations of the road textures AND the terrain textures, and using
those
> instead of the normal terrain texture.  But that limits how freely the
roads
> can be designed, and would duplicate the number of terrain textures I'm
> loading already (which is more than I should be as it is).
>
> The first method makes the most sense to me, but breaking an initial quad
up
> into all the needed polygons is a bit beyond me, at least without spending
> months developing spme really ugly code for it.
>
> If anyone has even the slightest suggestion I'm all ears.
>
> Scott
> Virtopia 2 3D Project
> http://vp2.onebigvillage.com
>
>
>
>

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