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Elnof
 Post subject: Get Vertex Location
PostPosted: 12.12.2011, 04:24 
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Joined: 14.07.2011, 02:18
Posts: 20
I'm hoping to use collision meshes for a game engine that I'm working on and I was curious if Horde3D has some method for retrieving vertex locations. I'm guessing that I'd use h3dFineNode(Mesh), though I don't know if I can get specific vertices from that. Thank you in advance!

On a side not, if anyone could point me to a good tutorial on content creation for Horde, I'd appreciate it.
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Irdis
 Post subject: Re: Get Vertex Location
PostPosted: 12.12.2011, 09:00 
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Joined: 17.11.2009, 17:00
Posts: 205
Location: Russia, Moscow
Hi, Elnof.
If you wish to get vertex data from mesh, you can find the code here.
I should warn you that the code is untested. You can find more detailed code in Horde Bullet Physics Integration.
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Elnof
 Post subject: Re: Get Vertex Location
PostPosted: 12.12.2011, 21:50 
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Joined: 14.07.2011, 02:18
Posts: 20
Sweet. Thank you. I'll look this over as soon as I have time.

I glanced at it and noticed that the code assumed that there would only be one mesh per model. Getting the handle for various meshes is just a matter of changing the index in h3dGetNodeChild(model, index), right?
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Irdis
 Post subject: Re: Get Vertex Location
PostPosted: 13.12.2011, 08:31 
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Joined: 17.11.2009, 17:00
Posts: 205
Location: Russia, Moscow
Yes. You can do something like that:
Code:
   h3dFindNodes(H3DRootNode, "model_name", H3DNodeTypes::Mesh); // find your mesh
   H3DNode mesh = h3dGetNodeFindResult(0);   
       
   int i = 0;
   H3DNode childMesh = 0;
   while( ( childMesh = h3dGetNodeChild( mesh, i++ ) ) != 0 )
   {
        // your code here
   }
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Elnof
 Post subject: Re: Get Vertex Location
PostPosted: 15.01.2012, 09:04 
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Joined: 14.07.2011, 02:18
Posts: 20
I have that code mostly working now (just some simple problems I should be able to figure out). Thank you for linking it to me.
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Elnof
 Post subject: Re: Get Vertex Location
PostPosted: 15.01.2012, 23:29 
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Joined: 14.07.2011, 02:18
Posts: 20
Quick question:
Code:
unsigned int numVertices = h3dGetNodeParamI(mesh, H3DMesh::VertREndI) - h3dGetNodeParamI(mesh, H3DMesh::VertRStartI) + 1;
In my model with 40 verticies, numVertices is equal to 120. I assume that's because the vertex index is only a single dimension so numVertices = vertices * 3? However, when I loop through to put nodes a the vertices, I have to multiply numVertices by three again or I don't get them all.
Code:
for(int i = 0; i < numVertices * 3; i += 3) {
    H3DNode newbox = h3dAddNodes(holder, boxres);
    h3dSetNodeTransform(newbox, sx * vertexBase[i], sy * vertexBase[i + 1], sz * vertexBase[i + 2], 0, 0, 0, .1, .1, .1);
}


Why is that? All the vertices are correct, so I'm not sure whether I'm using the vertex index incorrectly or whether the geometry resource has duplicates.
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Irdis
 Post subject: Re: Get Vertex Location
PostPosted: 16.01.2012, 10:10 
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Joined: 17.11.2009, 17:00
Posts: 205
Location: Russia, Moscow
In the Bullet Physics module getting vertices from mesh was handled like this:
Code:
// Create new mesh in physics engine
            m_btTriangleMesh = new btTriangleMesh();
            int offset = 3;
            //if (triangleMode == 5) // Triangle Strip
            //   offset = 1;

            // copy mesh from graphics to physics
            bool index16 = false;
            if (TriangleBase16)
               index16 = true;

            for (unsigned int i = 0; i < numTriangleIndices - 2; i+=offset)
               {
                  unsigned int index1 = index16 ? (TriangleBase16[i]   - vertRStart) * 3 : (TriangleBase32[i]   - vertRStart) * 3;
                  unsigned int index2 = index16 ? (TriangleBase16[i+1] - vertRStart) * 3 : (TriangleBase32[i+1] - vertRStart) * 3;
                  unsigned int index3 = index16 ? (TriangleBase16[i+2] - vertRStart) * 3 : (TriangleBase32[i+2] - vertRStart) * 3;

                  m_btTriangleMesh->addTriangle(
                     btVector3(vertexBase[index1], vertexBase[index1+1], vertexBase[index1+2] ),
                     btVector3(vertexBase[index2], vertexBase[index2+1], vertexBase[index2+2] ),
                     btVector3(vertexBase[index3], vertexBase[index3+1], vertexBase[index3+2] )
                  );
               }   

So basically your first step is to get triangle indices and only then you can get the vertex.
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Elnof
 Post subject: Re: Get Vertex Location
PostPosted: 19.01.2012, 01:52 
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Joined: 14.07.2011, 02:18
Posts: 20
I'm getting the correct number of faces now, and I suppose that's what really matters. Thank you.
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Elnof
 Post subject: Re: Get Vertex Location
PostPosted: 24.01.2012, 23:51 
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Joined: 14.07.2011, 02:18
Posts: 20
The geometry resource will not change based on animations, correct?

Edit:

The geometry does have duplicate vertices. Is there a reason for this?
Code:
Vertex Location @ Index:

(1, 1, -1) @ 0
(-1, 1, 1) @ 3
(0.999999, 1, 1) @ 6
---
(1, 1, -1) @ 0
(-1, 1, -1) @ 9
(-1, 1, 1) @ 3
---
(1, -1, 1) @ 12
(0.999999, 1, 1) @ 15
(-1, 1, 1) @ 18
---
(1, -1, 1) @ 12
(-1, 1, 1) @ 18
(-1, -1, 1) @ 21
---
(1, -1, -1) @ 24
(1, -1, 1) @ 27
(-1, -1, 1) @ 30
---
(1, -1, -1) @ 24
(-1, -1, 1) @ 30
(-1, -1, -1) @ 33
---
(1, -1, -1) @ 36
(0.999999, 1, 1) @ 39
(1, -1, 1) @ 42
---
(1, -1, -1) @ 36
(1, 1, -1) @ 45
(0.999999, 1, 1) @ 39
---
(-1, -1, 1) @ 48
(-1, 1, 1) @ 51
(-1, 1, -1) @ 54
---
(-1, -1, 1) @ 48
(-1, 1, -1) @ 54
(-1, -1, -1) @ 57
---
(1, 1, -1) @ 60
(-1, -1, -1) @ 63
(-1, 1, -1) @ 66
---
(1, 1, -1) @ 60
(1, -1, -1) @ 69
(-1, -1, -1) @ 63
---
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