IrrToNewton

[mrsquare]

Hi all - new member here, got a couple of questions for you clever people

I'm trying to integrate Newton physics together with a terrain heightmap. Its nothing too fancy - at the moment I'm just ripping out the terrain from the terrain tutorial and adding the physics from the Newton tutorial to a model.

The gravity works fine on the model, but it doesn't collide with the terrain at all - just falls into nothingness. Reading through lots of threads about this topic on here has given me some pointers, and it looks like the collision map isn't being built correctly. At the moment my code looks like:

Code: Select all

pxMesh = mpxLevel_TerrainNode->getMesh();

// Now create a collision tree using all the triangles in our mesh
mpxLevel_NewtonCollisionMap = NewtonCreateTreeCollision( mpxLevel_NewtonWorld, NULL );

NewtonTreeCollisionBeginBuild( mpxLevel_NewtonCollisionMap );

nMeshBufferCount = pxMesh->getMeshBufferCount();

for( nLoop = 0; nLoop < nMeshBufferCount; nLoop++)
{	
//etc etc

The problem seems to be that nMeshBufferCount always comes out as zero, so nothing is ever actually added to the collision map by the loop One thread (http://irrlicht.sourceforge.net/phpBB2/ ... rrtonewton) I found mentioned something about using getMeshBufferForLOD instead - if correct I don't really get how that would work - do you then use the resulting SMeshBufferLightMap in place of the terrain mesh buffer?


Also... in loads of Newton threads I keep seeing references to some mysterious variable called 'IrrToNewton'. This doesn't seem to be defined anywhere that I can see - what is its value and where (if anywhere) can it be found? Am I missing some important #include file?

[MikeR]

I can't tell you why it isn't working, I've never got Newton integrated into any of my apps.

But, the irrtonewton is: a convertor.

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// use scale factor between Newton and IRR
const float NewtonToIrr = 32.0f;
const float IrrToNewton = (1.0f / NewtonToIrr);

Hope that helps a bit at least.

Edit to add: It's found in the global.h files in the demos.

[pfo]

The problem seems to be that nMeshBufferCount always comes out as zero, so nothing is ever actually added to the collision map by the loop

That's strange, there should be at least 1 mesh in there. The terrain is loading properly (apart from collision)? Yeah, you could also use getMeshBufferForLOD, you are correct in that you use that in place of the mesh buffer (actually, an SMeshBufferLightMap is very similar to a mesh buffer).

Also... in loads of Newton threads I keep seeing references to some mysterious variable called 'IrrToNewton'. This doesn't seem to be defined anywhere that I can see - what is its value and where (if anywhere) can it be found?

It's a scaling constant that some people apply. I don't understand why, some people think it gets better results w/ Newton. You are not required to use it, in my opinion if my units in my graphics and physics engines were of different sizes for the same object, I'd probably go insane.

[Guest]

mrsquare how do you get the gravity thing working for the terrain.......

can u pls show the code to me

thxs alot for helping me