Recenter World Space?

Z

ZHaDoom

Newcomer
Joined
Jul 12, 2003
Messages
4
Location
Southfield, Michigan USA
I am rendering multiple X Meshes. Each requires me to move the world and rotate before I Render the object. I can rotate and move back to the center of the world for my point of referance, but eventualy i get a roundering error with a visual byproduct.

They must be an easier way to recenter the object world. What am i missing?:confused:

Thanks
ZHaDoom
Code: 
void cXObject::Render(D3DXVECTOR3 m_dvPosition,D3DXVECTOR3 m_dvRotation)
{
	
	D3DXMATRIXA16 matWorld;
	D3DXMATRIXA16 matWorldY;
	
	//Move to object location
	D3DXMatrixTranslation(&matWorld,m_dvPosition.x,m_dvPosition.y,m_dvPosition.z);
	l_pd3dDevice->MultiplyTransform(D3DTS_WORLD, &matWorld);

	//Rotate object
	D3DXMatrixRotationY( &matWorldY, m_dvRotation.y );
	l_pd3dDevice->MultiplyTransform(D3DTS_WORLD, &matWorldY);

	//Render Object
	for( DWORD i=0; i<NumMaterials; i++ )
	{
		// Set the material and texture for this subset
		l_pd3dDevice->SetMaterial( &Materials[i] );
		l_pd3dDevice->SetTexture( 0, Textures[i] );

		// Draw the mesh subset
		Mesh->DrawSubset( i );
	}
	
	//Unrotate 
	D3DXMatrixRotationY( &matWorldY, -m_dvRotation.y );
	l_pd3dDevice->MultiplyTransform(D3DTS_WORLD, &matWorldY);

	//Move back to center of world space
	D3DXMatrixTranslation(&matWorld,-m_dvPosition.x,-m_dvPosition.y,-m_dvPosition.z);
	l_pd3dDevice->MultiplyTransform(D3DTS_WORLD, &matWorld);

	return;
}
 
I usually start with an identity matrix and multiply by the rotation for each object (or have each object store it's current world matrix). Having to "unturn" the world matrix so the next mesh can use it is bound to cause problems.

I've seen references where others use a counter and re-initialize the world matrix to an identity only after x number of iterations. Never tried it myself though.

-Ner
 
hmm.

Sounds right. Now i just need to figure out how to have seperate "world_matrix" for each object.
Ive try setting the world matrix to the identy matrix but it seems to be from the last rendered object. I'll play around and get back with you.

Thanks
ZHaDoom


:-\Nerseus, Thanks for the quick repley.
 
Still Dazed and Confused

Ok help me out. I setup what i think are sepearte world matrixs for each module. But when i render them it still moves based on the last render location. I only call CalcMatrix when I Create the object. Ack.

ZHaDoom.

Code: 
//Call To Create an object
	cModuleptr	m_ptrModule;
	D3DXVECTOR3 m_D3DXVECTOR3(0,0,0);
	D3DXVECTOR3 m_D3DXVRotation (0,0,0);

	m_ptrModule=new cModule();
	m_ptrModule->Vector=m_D3DXVECTOR3;
	m_ptrModule->Rotation=m_D3DXVRotation;
	m_ptrModule->ptrMesh=&g_PowerStation;
	m_ptrModule->CalcMatrix();

	g_StartModule=m_ptrModule;
		
	
// Module Class

cModule* ptrNext;
cXObject* ptrMesh;
D3DXMATRIXA16 matModule;
	
void cModule::CalcMatrix(void)
{

	//Create World matrix for this module
	D3DXMatrixIdentity(&matModule);
	D3DXMatrixTranslation(&matModule,Vector.x,Vector.y,Vector.z);

}


void cModule::Render(void)
{

	D3DXMATRIXA16 matWorld;


	//Try to recenter world (dosen't appear to do anything )
	D3DXMatrixIdentity(&matWorld);
	ptrMesh->l_pd3dDevice->MultiplyTransform(D3DTS_WORLD, &matWorld);

	//Move to Modual World space (still moving from last render =( 
	ptrMesh->l_pd3dDevice->MultiplyTransform(D3DTS_WORLD, &matModule);


	//Render Module
	for( DWORD i=0; i<ptrMesh->NumMaterials; i++ )
	{
		// Set the material and texture for this subset
		ptrMesh->l_pd3dDevice->SetMaterial( &ptrMesh->Materials[i] );
		ptrMesh->l_pd3dDevice->SetTexture( 0, ptrMesh->Textures[i] );

		// Draw the mesh subset
		ptrMesh->Mesh->DrawSubset( i );
	}

	return ;
}
 
Got it.

Something simple =) I should have been using SetTransform instead of MultiplyTransform.

Code: 
void cModule::Render(void)
{

	ptrMesh->l_pd3dDevice->SetTransform(D3DTS_WORLD, &matModule);

	for( DWORD i=0; i<ptrMesh->NumMaterials; i++ )
	{
		// Set the material and texture for this subset
		ptrMesh->l_pd3dDevice->SetMaterial( &ptrMesh->Materials[i] );
		ptrMesh->l_pd3dDevice->SetTexture( 0, ptrMesh->Textures[i] );

		// Draw the mesh subset
		ptrMesh->Mesh->DrawSubset( i );
	}

	return ;
}
 
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