Hello, At first... sorry for my english... Well... I'm trying to develop a directx application to move a simple object (like a square) in the world space... This movement consist of all kind of rotation (yaw, pitch and roll) and the translation. I created an object class which contains some methods, variables and four versores (vPos, vUp, vRight, vLook) to store transformations object's informations... When user pushes the left and right keys I want to execute yaw rotation around the square's local Y-axis... I associated left key with this method:

void CObject::YawLeft(void)
{
	yaw -= rotationSpeed;
	D3DXMATRIX m;
	D3DXMatrixRotationAxis(&m, &vUp, -rotationSpeed);
	// rotate another axis around Y-axis
	D3DXVec3TransformCoord(&vRight, &vRight, &m);
	D3DXVec3TransformCoord(&vLook, &vLook, &m);

}
//°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°

Similarly for right key:

void CObject::YawRight(void)
{
	yaw += rotationSpeed;
	D3DXMATRIX m;
	D3DXMatrixRotationAxis(&m, &vUp, rotationSpeed);
	// rotate another axis around Y-axis
	D3DXVec3TransformCoord(&vRight, &vRight, &m);
	D3DXVec3TransformCoord(&vLook, &vLook, &m);
}
//°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°

When user pushes the 'A' and 'D' keys I want to execute roll rotation around the square's local Z-axis... for A key:

void CObject::RollLeft(void)
{
	roll += rotationSpeed;
	D3DXMATRIX m;
	D3DXMatrixRotationAxis(&m, &vLook, rotationSpeed);
	// rotate another axis around Z-axis
	D3DXVec3TransformCoord(&vUp, &vUp, &m);
	D3DXVec3TransformCoord(&vRight, &vRight, &m);
}
//°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°

and for D key:

void CObject::RollRight(void)
{
	roll -= rotationSpeed;
	D3DXMATRIX m;
	D3DXMatrixRotationAxis(&m, &vLook, -rotationSpeed);
	// rotate another axis around Z-axis
	D3DXVec3TransformCoord(&vUp, &vUp, &m);
	D3DXVec3TransformCoord(&vRight, &vRight, &m);
}
//°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°

For pitch:

void CObject::PitchUp(void)
{
	pitch -= rotationSpeed;
	D3DXMATRIX m;
	D3DXMatrixRotationAxis(&m, &vRight, -rotationSpeed);
	// rotate another axis around X-axis
	D3DXVec3TransformCoord(&vUp, &vUp, &m);
	D3DXVec3TransformCoord(&vLook, &vLook, &m);

	rota=2;
}
//°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°

void CObject::PitchDown(void)
{
	pitch += rotationSpeed;
	D3DXMATRIX m;
	D3DXMatrixRotationAxis(&m, &vRight, rotationSpeed);
	// rotate another axis around X-axis
	D3DXVec3TransformCoord(&vUp, &vUp, &m);
	D3DXVec3TransformCoord(&vLook, &vLook, &m);

	rota=2;
}
//°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°

For movements I tried this:

void CObject::MoveRight(void)
{
	vPos += vRight * movementSpeed;  
}
//°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°

void CObject::MoveLeft(void)
{
	vPos -= vRight * movementSpeed; 
}
//°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°

void CObject::MoveForward(void)
{
	vPos += vLook * movementSpeed;  
}
//°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°

void CObject::MoveBackward(void)
{
	vPos -= vLook * movementSpeed; 
}
//°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°

Finally this is the code in the render function:

......
D3DXMATRIX world;
D3DXMATRIX trans;
D3DXMATRIX rot,rot2,rot3;

D3DXMatrixTranslation(&trans, vPos.x, vPos.y, vPos.z);
D3DXMatrixRotationAxis(&rot, &vUp, yaw);
D3DXMatrixRotationAxis(&rot2, &vRight, pitch);	
D3DXMatrixRotationAxis(&rot3, &vLook, roll);

world = rot * rot2 * rot3 * trans;

pD3DDevice->SetTransform(D3DTS_WORLD, &world);
......

Well... this code works fine for one rotation... but for other rotations the code doesn't work as I want!!! Please, how can I fix this problem? thx.

Two questions:

1) What is the second object doing? If the first one works, try commenting that one out and see if the second works, if so, then I would make sure your not sharing values or parenting one's world to another.

2) Why not just use a single matrix for the object... your transformation matrix, which contains all the rotations, scale, and translations. It seems like this way your doing a lot more calculations than you have to. Plus, even if the object doesn't move, on render your recalculating the world matrix.

Look at functions like:
D3DXMatrixRotationY
D3DXMatrixRotationX
D3DXMatrixRotationZ
etc...

Jeff.

Thx for your reply...

1) In my project there is only one object... for this object I need to implement all kind of rotations and translations... my problem is that I managed to make only one rotation at time (ex. yaw), if I try to add another kind of rotation for the same object (ex. roll and pitch) the actions together don't work.
Perhaps is it because I call this statements for every frame:
......
D3DXMATRIX world;
D3DXMATRIX trans;
D3DXMATRIX rot,rot2,rot3;

D3DXMatrixTranslation(&trans, vPos.x, vPos.y, vPos.z);
D3DXMatrixRotationAxis(&rot, &vUp, yaw);
D3DXMatrixRotationAxis(&rot2, &vRight, pitch);
D3DXMatrixRotationAxis(&rot3, &vLook, roll);

world = rot * rot2 * rot3 * trans;

pD3DDevice->SetTransform(D3DTS_WORLD, &world);
......

2)I don't know how to do it using only one matrix...

those functions:
D3DXMatrixRotationY
D3DXMatrixRotationX
D3DXMatrixRotationZ

I think they allow the rotations concerning the same local axis of the object... instead if I have to make rotation around Y-axis, the other 2 axis must rotate in operation of the first one... like the airplane's movements.

I hope you understand my english... ^^'

When you update the orientation you only need to apply the latest change. So, using YawLeft as an example, try replacing "yaw -= rotationSpeed;" with "yaw = -rotationSpeed;".

Also, you may find this rotation tutorial interesting.