Bullet Engine

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Bullet Engine

Post  LuisLee on Thu Sep 24, 2009 3:35 am

How to determine Two objects collide in Bullet Engine?
Should have a Boolean value, but I did not find,
Because I do not Familiar with the bullet engine.
I hope you can help me, thank you! Very Happy

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Re: Bullet Engine

Post  sio2interactive on Thu Sep 24, 2009 3:38 am

Humm this have been answered before... you can either use a SIO2sensor or directly the contact points... Check the forum for more info. You can also try your luck on the Bullet forum as Bullet issues are totally out of the scope of SIO2.

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Re: Bullet Engine

Post  LuisLee on Thu Sep 24, 2009 3:57 am

sio2interactive wrote:Humm this have been answered before... you can either use a SIO2sensor or directly the contact points... Check the forum for more info. You can also try your luck on the Bullet forum as Bullet issues are totally out of the scope of SIO2.

OK! Thank you for your reply!

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Re: Bullet Engine

Post  cgen2 on Thu Sep 24, 2009 8:07 pm

I've just got bullet collision working after a few days of swotting tutorial09, 061 and sio2physic/object code and trial and error testing. I use tut09 as my basic framework.

The Bullet user guide is terse. Rom must have figured it out but he's got a big brain. Mine is size of squirrel's ...

Nevertheless my collision detection callbacks are working reliably. I like collision callbacks because I can let Bullet manage interaction of objects and I just code collision reactions.

What I learned is that collisions happen between pairs of objects. Collisions may trigger many callbacks every main loop. (One for each colliding object and possibly per contact point if you are using a triangle mesh collision shape???). Triangle meshes seem to work well. Use a triangle mesh if your world is inside e.g. a skybox, making the collision shape tri mesh not box. Be very careful with the order of calls to physic/object functions if you are duplicating physic objects like in tut061. A big world is OK e.g. 700 x 700 x 350 for my flightsim. The Bullet user guide cautions against making object dimensions too small ( < 0.1 ). And as I want to count bullets/particles hits I scaled up. Bullet drains your fps big time. I found many issues with my Blender model; selecting actors and setting the right object types and bounds, centering object origin data with Blender's "control new" button and applying scaling and rotation (cntrl A) to objects. Other than that, it's a doddle ...

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Re: Bullet Engine

Post  LuisLee on Thu Sep 24, 2009 8:28 pm

cgen2 wrote:I've just got bullet collision working after a few days of swotting tutorial09, 061 and sio2physic/object code and trial and error testing. I use tut09 as my basic framework.

The Bullet user guide is terse. Rom must have figured it out but he's got a big brain. Mine is size of squirrel's ...

Nevertheless my collision detection callbacks are working reliably. I like collision callbacks because I can let Bullet manage interaction of objects and I just code collision reactions.

What I learned is that collisions happen between pairs of objects. Collisions may trigger many callbacks every main loop. (One for each colliding object and possibly per contact point if you are using a triangle mesh collision shape???). Triangle meshes seem to work well. Use a triangle mesh if your world is inside e.g. a skybox, making the collision shape tri mesh not box. Be very careful with the order of calls to physic/object functions if you are duplicating physic objects like in tut061. A big world is OK e.g. 700 x 700 x 350 for my flightsim. The Bullet user guide cautions against making object dimensions too small ( < 0.1 ). And as I want to count bullets/particles hits I scaled up. Bullet drains your fps big time. I found many issues with my Blender model; selecting actors and setting the right object types and bounds, centering object origin data with Blender's "control new" button and applying scaling and rotation (cntrl A) to objects. Other than that, it's a doddle ...

Thank you for your experience, I have great help. Cheers!
Very Happy

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