polygon_idx is only supported by some objects. Not all. On what kind
of mesh object are you trying this?
Greetings,
On 2/20/06, Amir Taaki <[EMAIL PROTECTED]> wrote:
> Hi,
>
> Apparently csHitBeam result stores the polygon index (polygon_idx) of the
> face that was hit. My goal is to get the normal vector of the face that has
> been hit by my csHitBeam test.
>
> iPolygonMesh* wpolymesh = world_mesh->GetMesh ()->GetMeshObject ()->
> GetObjectModel ()->GetPolygonMeshBase ();
> csTriangle* wtris = wpolymesh->GetTriangles ();
> csVector3* wverts = wpolymesh->GetVertices ();
>
> printf("index: %i\n",res.polygon_idx);
> if ((res.polygon_idx > 0) && (res.polygon_idx < wpolymesh->GetTriangleCount
> ()))
> {
> csTriangle tri = wtris [res.polygon_idx];
> int vertc = wpolymesh->GetVertexCount ();
>
> if ((tri.a < vertc) && (tri.b < vertc) && (tri.c < vertc))
> {
> csVector3 a = wverts [tri.a],
> b = wverts [tri.b],
> c = wverts [tri.c];
> printf("(%f, %f, %f) (%f, %f, %f) (%f, %f, %f)\n",a.x,a.y,a.z,b.x,b.y,
> b.z,c.x,c.y,c.z);
> csPoly3D poly;
> poly.AddVertex (a);
> poly.AddVertex (b);
> poly.AddVertex (c);
> csVector3 upthrust = poly.ComputeNormal () * force;
> ship_mech->AddForceDuration(upthrust, false,
> csVector3 (0,0,0), 0.1f);
> //pcmechobj->AddForceOnce (csVector3 (0,force,0), false, csVector3
> (0,0,0));
> //pcmechobj->SetLinearVelocity (pcmechobj->GetLinearVelocity () + csVector3
> (0,force,0));
> }
> }
>
> Here I'm basically getting the triangles and using the index to get the
> triangle, and get the verts for that face, construct a csPoly3D then use the
> ComputeNormal function.
>
> When I run it, I get some extreme negative value for res.polygon_idx!, so
> looking in the docs I see that polygon_idx is only valid for HitBeamObject
> (and not HitBeam for some strange reason).
> csReversibleTransform rt = world_mesh->GetMesh ()->GetMovable
> ()->GetFullTransform ();
> start = rt.Other2ThisRelative (start);
> end = rt.Other2ThisRelative (end);
> csHitBeamResult res = world_mesh->GetMesh ()->HitBeamObject (start, end);
>
>
> As above I'm converting the start and end to the mesh which I'm testing on
> into its local co-ordinates.
>
> Re-running the first piece of code, and now I see that even though I have a
> valid res.r (the hitbeam is working), that now res.polygon_idx is always -1
> ... What is going on here?
>
> Is there an easy way I can get the normal vector of the face that the
> hitbeam has intersected on the mesh?
>
> Thanks.
>
> Amir Taaki
>
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