Changing TriMesh geometry on the fly

Troubleshooting graphics
1

Hi,



How do I change the geometry of a TriMesh on the fly?



After I have set the new vertex positions with   


public void reconstruct(FloatBuffer vertices, FloatBuffer normal,
            FloatBuffer color, FloatBuffer texture, IntBuffer indices)



what should I call so that the geometry is updated?

Currently I'm just calling updateModelBound();

Also, is there some other way than calling reconstruct to do this?
2

You can acces the buffers directly too, that's all it takes. Make sure you don't use any locking or VBO though!

3

Ok, cool. 



Are locks or VBO:s automatically activated somehow?  Do I need to turn them off?  If so, how?

4

Not if you just use your own trimesh. Some jME classes use it though (eg TerrainBlock)

5

Ok, thanks.



The reason things don't show up must be some bug in my own code then :slight_smile:

6

I use terrainblocks - but I have to call .updateFromHeightMap() on my TB each time I modify it - I suspect trimesh has something similar after you modify the underlying height array?

7

Terrainblocks use VBO, as mentioned.



Really, for a regular trimesh, all updates should be taken into account for the next rendering.

8

I figured out the problem (unrelated to this, had forgot to initialize something).



I'm doing a TriMesh that changes number of used vertexes (it's a brush stroke in a painting application).  To get it to ignore the vertexes that are not yet used from the buffers, I had to set the limit of the vertex, index, etc. buffers, and then call the reconstruct method of TriMesh, passing in always the same buffers.  This way I can vary the number of vertexes I'm using in the TriMesh (up to the maximum size of the buffers I have allocated).  Setting the limit is a bit tricky (first set position, then call flip…  the buffers have a weird API).



I also called updateModelBound(), as I guess that is needed to recalculate the bounds whenever changing the geometry manually.