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Mesh Racetrack Solid!? HALP! =D

Kristen Coledale

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Hi everyone!  Thanks in advance for reading this!  Today we decided to build a racetrack that we would eventually scale up and have a blast racing our crazy vehicles on!  I made it in blender, uploaded it and it looks great but...it's one big solid.   We can't walk along the track's hills and curves etc.  Making it phantom and filling it with prims would completely defeat the purpose......


Anyone know why, and is there a way to fix / avoid this problem? 


Thanks in advance!






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You need to make and upload a special physics model to make the physics work. It is a pain but you will get it. LOTS of information on this board. I suggest you look for posts by Drongle McMahon  and physics model. That should get you good background.

Sure others will answer too :D. A good board here.

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Hi  :)

1: The largest you could scale your track along any axis would be 64 meters. This would be way too small to race on.

2: For racing you  need barriers along the inner and outer edges of the track.

3: Because it has to be so big you need to work on keeping the the vertice count to a minimum otherwise the LI will be very high.

4: And of course as Chic has already mentioned  it needs to have a physics mesh.

  So you need to create a Low-poly Modular track with barriers included.

  This means the minimum will be:
                                  1 length of straight track mesh,         for example: 50m x 10m.
                                  1 Physics/collision mesh for the above.
                                  1 length of 90° curve track ,             for example: based on a circle with radius 25m.
                                  1 Physics/collision mesh for the curve track mesh.

Rather than explain it in picture form I have posted a .blend file here:  http://www.pasteall.org/blend/24375
for you to have a look at and try uploading.

                                 On layer 1 is the 50 meters of straight track.
                                 On layer 6 (below layer 1) is the physics shape mesh for the straight track mesh, simple Planes

                                 On layer 2 is the 90° curve.
                                 On layer 7 is the physics mesh for the curve track.

There are basically two types of physics mesh that would work for your track, 1 using non overlapping box shapes and the second using simple planes.
I have used the simple planes method in the .blend file because in this case it was quicker to model and when tested was working well at collisions of over 100km/h .
Note for high speeds the box method would be better better, see this thread:
but I leave  that to you experiment with. Also higher Physical barriers are often used on outside curves on many tracks.
This would involve creating hidden geometry in the track mesh so that the collision mesh would be a lot higher than the visible mesh. Again if you are interested another thing to look into .

This morning Using 6 lengths of straight track and 8 curves I created a working 600m+ long track for less than LI=50.

track test.png

Ok how to Upload:
  Select and export to Collada the Straight track mesh, (layer1) then do the same for the straight track Physics mesh (layer 6) so that you have , for example

            1  Straight.dae file
and      1  Straight Phys.dae file

In the Mesh Uploader panel Upload the Straight.dae as you normally would for the High LOD mesh :

Uploader Track mesh.png

Then hit the Physics tab in the Uploader and in Step 1, upload the Physics mesh ( do NOT hit the Analyze button ) 

Uploader Track Physics mesh.png

Calculate Weights and fees and then Upload.

Rez the mesh and edit it. From the Edit panel go to the Features tab and change the Physics Shape type: from Convex Hull to Prim.


You should now be able to use the track and collide with the barriers.

Upload in the same way the curved piece of track along with its Physics mesh.

As Chic said if you do a search in these forums you will find many threads covering Physics for  meshes  . The above is only to give you some idea of what you need to do to get your track to be drivable .

Note: Be carefull when rezzing large mesh items , if you rez it on top of yourself or another Avatar, even when you set the Physics shape to Prim it may well seem to be Phantom !

Note: On layer 3 is a Fly-over straight for figure of 8 tracks.

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