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fitfool

Calculating movement

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So, i now have a camera that is able to: move forward / back / left / right / turnleft / turnright. My problem is this situation... Say the user turns the camera to the left or right then wants to move forward based on were the camera is pointing. He pushes the key to move forward, but instead of the camera moving forward based were the camera is pointing, it moves forward into the z-axis. This is a obviously bug / flaw / whatever you want to call it and i have some questions on how to fix this. Would the easiest way to do this is to *somehow* calculate were the camera is poiting at, then calculate that into A translation? heres my code on how im moving my camera
void D3D_CUSTOMMATRIX::SetView( void )
{
	static float CamX = 0.0f;
	static float CamY = 1.0f;
	static float CamZ = 30.0f;
	static float CamRotX = 0.0f;

	if( KEY_DOWN('A') )
	{
		CamX += 0.5f;
	}

	if( KEY_DOWN('D') )
	{
		CamX -= 0.5f;
	}

	if( KEY_DOWN('W') )
	{
		CamZ-= 0.5f;
	}
	
	if( KEY_DOWN('S') )
	{
		CamZ += 0.5f;
	}

	if( KEY_DOWN(VK_LEFT) )
	{
		CamRotX += 1.0f;
	}

	if( KEY_DOWN(VK_RIGHT) )
	{
		CamRotX -= 1.0f;
	}
	
	D3DXMatrixLookAtLH( &View,
                       &D3DXVECTOR3(CamX, CamY, CamZ),    
                       &D3DXVECTOR3(CamX + CamRotX, 0.0f, 0.0f),    
                       &D3DXVECTOR3(0.0f, 1.0f, 0.0f) );
	
	return;
}


Thanks, fitfool

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[Source]

//here is a camera class set it up like this

Camera::Camera()
{
_cameraType = AIRCRAFT;

_pos = D3DXVECTOR3(0.0f, 0.0f, 0.0f);
_right = D3DXVECTOR3(1.0f, 0.0f, 0.0f);
_up = D3DXVECTOR3(0.0f, 1.0f, 0.0f);
_look = D3DXVECTOR3(0.0f, 0.0f, 1.0f);
}

Camera::Camera(CameraType cameraType)
{
_cameraType = cameraType;

_pos = D3DXVECTOR3(0.0f, 0.0f, 0.0f);
_right = D3DXVECTOR3(1.0f, 0.0f, 0.0f);
_up = D3DXVECTOR3(0.0f, 1.0f, 0.0f);
_look = D3DXVECTOR3(0.0f, 0.0f, 1.0f);
}

Camera::~Camera()
{

}

void Camera::getPosition(D3DXVECTOR3* pos)
{
*pos = _pos;
}

void Camera::setPosition(D3DXVECTOR3* pos)
{
_pos = *pos;
}

void Camera::getRight(D3DXVECTOR3* right)
{
*right = _right;
}

void Camera::getUp(D3DXVECTOR3* up)
{
*up = _up;
}

void Camera::getLook(D3DXVECTOR3* look)
{
*look = _look;
}

void Camera::walk(float units)
{
// move only on xz plane for land object
if( _cameraType == LANDOBJECT )
_pos += D3DXVECTOR3(_look.x, 0.0f, _look.z) * units;

if( _cameraType == AIRCRAFT )
_pos += _look * units;
}

void Camera::strafe(float units)
{
// move only on xz plane for land object
if( _cameraType == LANDOBJECT )
_pos += D3DXVECTOR3(_right.x, 0.0f, _right.z) * units;

if( _cameraType == AIRCRAFT )
_pos += _right * units;
}

void Camera::fly(float units)
{
// move only on y-axis for land object
if( _cameraType == LANDOBJECT )
_pos.y += units;

if( _cameraType == AIRCRAFT )
_pos += _up * units;
}

void Camera::pitch(float angle)
{
D3DXMATRIX T;
D3DXMatrixRotationAxis(&T, &_right, angle);

// rotate _up and _look around _right vector
D3DXVec3TransformCoord(&_up,&_up, &T);
D3DXVec3TransformCoord(&_look,&_look, &T);
}

void Camera::yaw(float angle)
{
D3DXMATRIX T;

// rotate around world y (0, 1, 0) always for land object
if( _cameraType == LANDOBJECT )
D3DXMatrixRotationY(&T, angle);

// rotate around own up vector for aircraft
if( _cameraType == AIRCRAFT )
D3DXMatrixRotationAxis(&T, &_up, angle);

// rotate _right and _look around _up or y-axis
D3DXVec3TransformCoord(&_right,&_right, &T);
D3DXVec3TransformCoord(&_look,&_look, &T);
}

void Camera::roll(float angle)
{
// only roll for aircraft type
if( _cameraType == AIRCRAFT )
{
D3DXMATRIX T;
D3DXMatrixRotationAxis(&T, &_look, angle);

// rotate _up and _right around _look vector
D3DXVec3TransformCoord(&_right,&_right, &T);
D3DXVec3TransformCoord(&_up,&_up, &T);
}
}

void Camera::getViewMatrix(D3DXMATRIX* V)
{
// Keep camera's axes orthogonal to eachother
D3DXVec3Normalize(&_look, &_look);

D3DXVec3Cross(&_up, &_look, &_right);
D3DXVec3Normalize(&_up, &_up);

D3DXVec3Cross(&_right, &_up, &_look);
D3DXVec3Normalize(&_right, &_right);

// Build the view matrix:
float x = -D3DXVec3Dot(&_right, &_pos);
float y = -D3DXVec3Dot(&_up, &_pos);
float z = -D3DXVec3Dot(&_look, &_pos);

(*V)(0,0) = _right.x; (*V)(0, 1) = _up.x; (*V)(0, 2) = _look.x; (*V)(0, 3) = 0.0f;
(*V)(1,0) = _right.y; (*V)(1, 1) = _up.y; (*V)(1, 2) = _look.y; (*V)(1, 3) = 0.0f;
(*V)(2,0) = _right.z; (*V)(2, 1) = _up.z; (*V)(2, 2) = _look.z; (*V)(2, 3) = 0.0f;
(*V)(3,0) = x; (*V)(3, 1) = y; (*V)(3, 2) = z; (*V)(3, 3) = 1.0f;
}

void Camera::setCameraType(CameraType cameraType)
{
_cameraType = cameraType;
}
[/Source]

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Simple. Build a rotation matrix for your camera, then multiply the point {0, 0, z, 0} by it, where z is the speed that you want your camera to move forwards. Then add the resulting vector with your camera's position.

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