Re: [Plib-users] Intersection Testing / 3ds loading

[Steve B. <sjb...@ai...>]

> Thomas Gahr wrote:
> 
> I am writing a game with PLIB it's a kind of 3d jump n run (like "tux a quest fo herring"). First I used heightmaps (modified majik-example), but now I wanted to use models for my terrain.
> I made some models using anim8or and tried to load them.

What file format does anim8or write?

> Most of them were white, although I applied materials and if i applied textures
> they were stretched over the whole model (but I think that's a problem in anim8or).

...or the PLIB file loader for whatever format you are using.

> Can I apply states to ssgEntities?

No - only ssgLeaf nodes.

> How can I modify the VtxTables (or whatever the loader uses to store
> the veritces) of the model I loaded?

RTFM!  There is API for ssgVtxTable that allows access to the vertex tables
themselves.

> Now (that I have models for the terrain with some walls and steep planes) I wanted to use the
> LOS-intersection testing for checking if I am running against a wall.

TuxAQFH and TuxKart both use bounding sphere intersection tests for that - it works much better
than the alternatives.

> Then I tried the Isect-method with a sphere:
> 
>     sgVec3 test_vec ;
>     sgMat4 invmat ;
>     sgMakeIdentMat4 ( invmat ) ;
>     sgSphere *sphere;
> 
>     invmat[3][0] = -pos[0] ;
>     invmat[3][1] = -pos[1] ;
>     invmat[3][2] = -(pos[2]+1.5) ;
> 
>     sphere = new sgSphere;
> 
>     sphere->setCenter(0.0,0.0,1.2);
>     sphere->setRadius(1.0);
> 
>     ssgHit *results ;
>     int num_hits = ssgIsect ( tscene, sphere, invmat, &results ) ;
> 
>     float ehot = -1000000.0f ;
> 
>     for ( int i = 0 ; i < num_hits ; i++ )
>     {
>       ssgHit *eh = &results [ i ] ;
> 
>       float ehgt = - eh->plane[3] / eh->plane[2] ;
>       if ( ehgt >= ehot )
>         ehot = ehgt ;
>     }
> The Program crashes when I increase the sphere's radius

That's rather suprising - where exactly does it die?

----------------------------- Steve Baker -------------------------------
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