Newton & Irrlicht Terrain ?

[the_user as guest]

Hi,
have anybody a sample code for collisions with Newton and Irrlicht Terrain?!
or an idea have i can release this?

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Hat jemand ein Beispiel code für collisions mit Newton und dem Irrlicht Terrain??
Oder eine Idee wie man das machen könnte?

[the_user as guest]

Hi, i write a function for Newten & Irrlicht Terrain based on an Newten Tutorial and an post in Newton Game Dynamics Forum
http://newtondynamics.com/forum/viewtop ... hlight=nwt.
But i have a problem nothing collision with the terrain.
Can anybody help me?
Or see anybody a bug?

PS: I waiting since 2 days for an email with my password for the irrlicht forum.

Sorry for my bad english.

Code: Select all

#include "StdAfx.h"

core::stringw               wStr1; 
const float IrrToNewton = 1.0f / 1024.0f; 
const float NewtonToIrr = 1024.0f;

void CGame::CT2()
{
    //scene::ITerrainSceneNode* terrain;
    char meshName[255] ="XYZ"; 
    core::dimension2d<f32>      stretchSize; 
    //scene::IAnimatedMesh*       terrainMesh; 
    //scene::ISceneNode*          terrainNode; 
    video::IImage*              heightMapImage; 
    video::IImage*              texture;
    
    stretchSize = core::dimension2d<f32> ( 32.125f, 32.125f ); 
    
    texture        = driver->createImageFromFile ( "../../media/terrain-texture.jpg" );
    heightMapImage = driver->createImageFromFile ( "../../media/terrain-heightmap.bmp" );
    
    driver->beginScene ( true, true, video::SColor ( 0, 0, 0, 0 ) ); 
    wStr1 = L"Loading Terrain..."; 
    guienv->getBuiltInFont ( )->draw ( wStr1.c_str ( ), core::rect<s32> ( 0, 0, 200, 150 ), video::SColor ( 128, 255, 0, 0 ), true, true ); 
    driver->endScene ( ); 
    
    g_map = smgr->addTerrainMesh ( meshName, texture, heightMapImage, stretchSize, 256.0f, core::dimension2d<s32> ( 64, 64 ) ); 

    g_mapnode = smgr->addOctTreeSceneNode ( g_map, smgr->getRootSceneNode ( ), -1, 128 ); 
    
	//g_mapnode->setMaterialTexture(1, driver->getTexture("../../media/detailmap3.jpg"));
	
	g_mapnode->setMaterialType(video::EMT_DETAIL_MAP);
		
	driver->beginScene ( true, true, video::SColor ( 0, 0, 0, 0 ) ); 
    wStr1 = L"Loading Newton..."; 
    guienv->getBuiltInFont ( )->draw ( wStr1.c_str ( ), core::rect<s32> ( 0, 0, 200, 150 ), video::SColor ( 128, 255, 0, 0 ), true, true ); 
    driver->endScene ( ); 
	
	
	/*light = smgr->addLightSceneNode(0, core::vector3df(0,30,0), 
           video::SColorf(1.0f, 1.0f, 1.0f, 1.0f), 6000.0f); */

	//////////////////////////////////////////////////////////////////////////
	//
	// Create the newton collision tree from the map mesh
	//
	// Remember to use (video::S3DVertex) if you are loading a mesh without lightmaps
	// for your level. (Like a .x or .3ds level)
	//
	//////////////////////////////////////////////////////////////////////////
	g_newtonmap = NewtonCreateTreeCollision(nWorld, NULL);
	NewtonTreeCollisionBeginBuild(g_newtonmap);
	int cMeshBuffer, j;
	int v1i, v2i, v3i;
	scene::IMeshBuffer*  mb                   = NULL; 
	core::vector3df      vArray[3], e0, e1, area; // vertex array (3*3 floats)
    float                mag                  = 0.0f; 

	int tmpCount = 0;

	for (cMeshBuffer=0; cMeshBuffer<g_map->getMesh(0)->getMeshBufferCount(); cMeshBuffer++)
	{	
		mb = g_map->getMesh(0)->getMeshBuffer(cMeshBuffer);

		video::S3DVertex2TCoords* mb_vertices = (irr::video::S3DVertex2TCoords*)mb->getVertices();

		u16* mb_indices  = mb->getIndices();

		// add each triangle from the mesh
		for ( j = 0; j < mb->getIndexCount ( ); j += 3 ) 
            { 
               //printf("Ding Dong\n");
               
               v1i = mb_indices[j]; 
               v2i = mb_indices[j + 1]; 
               v3i = mb_indices[j + 2]; 

               vArray[0] = mb_vertices[v1i].Pos * IrrToNewton; 
               vArray[1] = mb_vertices[v2i].Pos * IrrToNewton; 
               vArray[2] = mb_vertices[v3i].Pos * IrrToNewton; 

               e0 = vArray[1] - vArray[0]; 
               e1 = vArray[2] - vArray[0]; 

               area = e0.crossProduct ( e1 ); 
               mag = area.dotProduct ( area ); 

               if ( mag > -0.00001 ) 
                  NewtonTreeCollisionAddFace ( g_newtonmap, 3, &vArray[0].X, 12, 1 ); 
            } 

	}
	NewtonTreeCollisionEndBuild(g_newtonmap, 0);
	g_newtonmapbody = NewtonCreateBody(nWorld, g_newtonmap);

	
	// set the newton world size based on the bsp size
	float boxP0[3]; 
	float boxP1[3]; 
	float matrix[4][4]; 
	NewtonBodyGetMatrix (g_newtonmapbody, &matrix[0][0]); 
	NewtonCollisionCalculateAABB (g_newtonmap, &matrix[0][0],  &boxP0[0], &boxP1[0]); 
	// you can pad the box here if you wish
	//boxP0.y -= somevalue; 
	//boxP1.y += somevaluef; 
	NewtonSetWorldSize (nWorld, (float*)boxP0, (float*)boxP1);
		
}

[pfo]

Why do you do this ? :

e0 = vArray[1] - vArray[0];
e1 = vArray[2] - vArray[0];

area = e0.crossProduct ( e1 );
mag = area.dotProduct ( area );

if ( mag > -0.00001 )
NewtonTreeCollisionAddFace ( g_newtonmap, 3, &vArray[0].X, 12, 1 );

Maybe take this code out? I have terrain collisions working with Newton, I did not take a step like this. Try replacing with just:

NewtonTreeCollisionAddFace ( g_newtonmap, 3, &vArray[0].X, 12, 1 );

Also, I believe this code is incorrect:

vArray[0] = mb_vertices[v1i].Pos * IrrToNewton;
vArray[1] = mb_vertices[v2i].Pos * IrrToNewton;
vArray[2] = mb_vertices[v3i].Pos * IrrToNewton;

Do it like this:

vArray[0] = mb_vertices[v1i].Pos;
vArray[1] = mb_vertices[v2i].Pos;
vArray[2] = mb_vertices[v3i].Pos;

I don't know why you used the scaling factor. I had a hard time setting this up, it helps to get a feel for where things are being placed, I figured this out by writing all of my vertices in the terrain to a file so I could verify they were being added correctly. It's not pretty nor fun, but it did help. I do not have my code in front of me (I'm at work) but try the fixes I suggested and if they don't work, I'll post my code to setup Newton Terrain using a mesh buffer.

[the_user]

Hi,
thank you for the answer.

I try your tip but my application stop/crash at

Code: Select all

NewtonTreeCollisionAddFace ( g_newtonmap, 3, &vArray[0].X, 12, 1 );

I'm looking forward to your next answer and hope that you post your code.

[pfo]

Again, no code in front of me (sorry)

But I think I know what the problem is now:

Try passing vArray as an array of 9 floats, instead of using the core::vector3df

Newton assumes an array of 9 consecutive floats describing a face, it won't know how to handle a vector3df, and is probably accessing what it thinks is valid memory in a float array but instead causes a segmentation fault.

That SHOULD fix it, if not harass me to post the code

[pfo]

I got the code in front of me, might as well post it becuase I would have found this useful had it existed before I wrote it:

// get terrain mesh buffer for lod 0 (full detail) for collision physics
scene::SMeshBufferLightMap mb;
((scene::ITerrainSceneNode*)m_pNode)->getMeshBufferForLOD(mb, 0);

// these are very important to avoid crashes
mb.Indices.set_free_when_destroyed(false);
mb.Vertices.set_free_when_destroyed(false);

// create newton collision tree with terrain vertices
m_pCollision = NewtonCreateTreeCollision(pWorld, NULL);
NewtonTreeCollisionBeginBuild(m_pCollision);

// get vertex data
video::S3DVertex2TCoords *vertices = (video::S3DVertex2TCoords*)mb.getVertices();
int vi1, vi2, vi3;
int index_count = mb.getIndexCount();
u16 *indices = mb.getIndices();
float vArray[9];

// create collision tree faces
for (int i = 0; i < index_count; i += 3)
{
vi1 = indices;
vi2 = indices[i + 1];
vi3 = indices[i + 2];

// build face data
vArray[0] = vertices[vi1].Pos.X; vArray[1] = vertices[vi1].Pos.Y; vArray[2] = vertices[vi1].Pos.Z;
vArray[3] = vertices[vi2].Pos.X; vArray[4] = vertices[vi2].Pos.Y; vArray[5] = vertices[vi2].Pos.Z;
vArray[6] = vertices[vi3].Pos.X; vArray[7] = vertices[vi3].Pos.Y; vArray[8] = vertices[vi3].Pos.Z;

// add face to tree
NewtonTreeCollisionAddFace(m_pCollision, 3, vArray, 12, 1);
}

// finalize tree, create static body and set material id
NewtonTreeCollisionEndBuild(m_pCollision, 0);
m_pBody = NewtonCreateBody(pWorld, m_pCollision);


// optional for setting material ID (these are really fun)
// get physics material from environment and set
m_matID = m_pEnvironment->GetPhysicsID(m_sPhysics);
NewtonBodySetMaterialGroupID(m_pBody, m_matID);

[the_user]

Hi !
That work !!!!

Very Big Thank you !!!!