[ODE] Bounce and trimesh

[Tim Rightnour]

On 05-Dec-2004 Eike Decker wrote:
>  * Use dTerrain objects instead of trimeshs (wish I knew how to use them)

It's not as hard as it seems..

This is basically how I load my map:

 maph->mapspace = dHashSpaceCreate(maph->mapg->space);
 map->terrh = safer_malloc(sizeof(dReal) * square(maph->width));
 for (i=0, k=0; i<maph->width; i++) {
     for (j=0; j<maph->width; j++) {
         map->terrh[k] =
             groundheight_at_xz(map->elevation,
              (float)j*SCALE_XZ, (float)i*SCALE_XZ,
              maph->width, maph->width);
             k++;
         }
     }
 map->terrgeom = dCreateTerrainY(maph->mapspace, map->terrh,
                                 maph->width*SCALE_XZ, maph->width,
                                 1, 1);
 dGeomSetPosition(map->terrgeom, maph->x, maph->y, maph->z);

My map is stored internally as an (int8_t **) for historical purposes.  The
groundheight_at_xz just gives the height value at a specific x,z coordinate. 
That is stored in a big array of dReals (map->terrh) and passed as an argument
to dCreateTerrainY(). The maph->width*SCALE_XZ argument sets the size of my map
to 2560.0 x 2560.0.  Then I use dGeomSetPosition() to move it to the
appropriate spot.

Some hints when using dTerrain:

1) Don't attach the terrain to a body, lots of annoying things happen, like
your terrain being affected by gravity.
2) You will probably have to do a few checks in your collide callback for the
ground, to react differently to it.  In my case, I'm using multiple terrain
geoms to make a full world.  So I make the collision callback ignore
terrain/terrain hits.

---
Tim Rightnour <root at garbled.net>
NetBSD: Free multi-architecture OS http://www.netbsd.org/
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