Bullet performance on iPhone & iPod Touch

[sio2interactive]

Is there anyway too speed up the performance of bullet at the cost of less precision. I got a game level running on iPhone when physic is OFF Im around 20+ FPS, as soon as I start stepping in the simulation "btDiscreteDynamicsWorld->stepSimulation( dtime, 0 )" the FPS goes down at like 5+.

I don't really care if the simulation is like "super precise" I just want to speed up the overall physic calculation. Im already using #define USE_APPROXIMATION 1 and have modify the following parameters in btDefaultCollisionConfiguration.h:

// To use less memory...
m_defaultMaxPersistentManifoldPoolSize( 1638 ), //65536
m_defaultMaxCollisionAlgorithmPoolSize( 1638 ), //65536
m_defaultStackAllocatorSize( 131072 ) // 5 * 1024 * 1024

Is there anything else I can do to speed it up?

Tks in advance!

Cheers,

[sparkprime]

You haven't given any information about the simulation. How many bodies? Are they sparse or dense? What collision shapes? How many are static? What broadphase are you using? Can you run a profiler of some kind?

[sio2interactive]

Well take a look: http://www.youtube.com/watch?v=0vmgNJWJ1ug&fmt=18

It's pretty basic...

The terrain is divided in 3 static meshes and the monkeys are ConvexHull all the rest are their respective shapes. For the broadphase I use:

const btVector3 worldAabbMin( -1000.0, -1000.0, -1000.0 );
const btVector3 worldAabbMax( 1000.0, 1000.0, 1000.0 );

btBroadphaseInterface = new btAxisSweep3(worldAabbMin, worldAabbMax, 1638 );

[sparkprime]

i suppose you'll have to get some kind of profiling in there, even if it's just some hacked up debug output

you could try using the bvh broadphase instead but otherwise there's no point in guess

do some experiments

try just one dynamic body

try removing the terrain

try removing half the terrain

etc

[sio2interactive]

Is there any tutorials, can't seems to find anything in demos....

[sio2interactive]

What I mean is "is there a tutorial out there on the different broadphase that you can use?"

[sio2interactive]

Allright forget about all the fuss I got it

[Erwin Coumans]

Are you using a btConvexHullShape for the monkeys?

How many vertices are the moneys?
If there are more than 32 vertices, please try to reduce the number of vertices, by using the btShapeHull utility:

Code: Select all

btShapeHull shapeHull( originalMonkeyShape );
shapeHull.buildHull(0.01);
btConvexHullShape* newSimplifiedMonkeyShape = new btConvexHullShape(shapeHull.getVertexPointer(),shapeHull.numVertices());

Also, you can use the btDbvtBroadphase instead of btAxisSweep3 broadphase.
Hope this helps,
Erwin

[sio2interactive]

Allright good stuff, I definetly see an improvement!

Cheers!

[rubenjavier]

very cool indeed... did you used a dynamic or a kinematic charactercontroller? I havent been able to get the kinematic character to interact with the dynamic objects, and your character seems to lack the inhertia problems of a dynamic character controller but it collided with the cones... so I was wondering, did you found a way to collide the kinematic character with the dynamic objects?