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opengl euler angle camera problem

Started by xg0blin Jan 2, 2003 at 12:51 AM 2 replies 950+ views

Original Post

Jan 2, 2003 at 12:51 AM

I know, euler angles suck, but I''m doing a project on them (and quaternions) for school, so I have to demonstrate an euler angle camera. I have an axis-angle camera already, and I am trying to convert it to euler angle and quaternion. My euler angle cam is all screwy. It''ll work okay for a second, but then it does wierd stuff, like invert the mouse, or lock for a second and then unlock. I borrowed *some* of the camera code from gametutorials to do my testing, cause I figured maybe I had my mousemove function done badly. Here it is.

  
void Camera::RotateCamera(double Yaw, double Pitch, double Roll)
{
	Vector OriginView = View - Position, NewView;

	Yaw = (Yaw * PI)/180;
	Pitch = (Pitch * PI)/180;
	Roll = (Roll * PI)/180;

	double SinYaw = sin(Yaw);
	double CosYaw = cos(Yaw);
	double SinPitch = sin(Pitch);
	double CosPitch = cos(Pitch);
	double SinRoll = sin(Roll);
	double CosRoll = cos(Roll);

	NewView.x =  CosRoll * CosYaw * OriginView.x;
	NewView.x += (-SinRoll * CosPitch + CosRoll * SinYaw * SinPitch) * OriginView.y;
	NewView.x += (-SinRoll * -SinPitch + CosRoll * SinYaw * CosPitch) * OriginView.z;

	NewView.y =  (SinRoll * CosYaw) * OriginView.x;
	NewView.y += (CosRoll * CosPitch + SinRoll * SinYaw * SinPitch) * OriginView.y;
	NewView.y += (CosRoll * -SinPitch + SinRoll * SinYaw * CosPitch) * OriginView.z;

	NewView.z =  -SinYaw * OriginView.x;
	NewView.z += (CosYaw * SinPitch) * OriginView.y;
	NewView.z += (CosYaw * CosPitch) * OriginView.z;

	View = Position + NewView;
}

void Camera::SetViewByMouse(void)
{
	int MouseX, MouseY;
	int CenterX = SCREENWIDTH / 2;
	int CenterY = SCREENHEIGHT / 2;
	int DirectionX;
	int DirectionY;
	static double CurrentRotationY = 0.0;

	SDL_GetMouseState(&MouseX, &MouseY);

	if(MouseX == CenterX && MouseY == CenterY)
		return;

	SDL_WarpMouse(CenterX, CenterY);

	DirectionX = (CenterX - MouseX)/10;
	DirectionY = (CenterY - MouseY)/10;
	
	CurrentRotationY -= DirectionY;

	if(CurrentRotationY >= 50.0)
		CurrentRotationY = 50.0;
	else if(CurrentRotationY <= -50.0)
		CurrentRotationY = -50.0;
	else
		RotateCamera(DirectionX, DirectionY, 0);
}

anybody got a fix?

xg0blin

Jan 2, 2003 at 2:30 AM

Ok, I got part of it fixed. It no longer inverts the camera, as I added a check to see what quadrant the view vector is in in regards to the origin on the x/z plane. The camera is still very jerky though, and sometimes it will keep me from going too far on the y-plane. Kind of irritating. The rotatecamera function is the same. HEre is the new mousemove function

  
void Camera::SetViewByMouse(void)
{
	int MouseX, MouseY;
	int CenterX = SCREENWIDTH / 2;
	int CenterY = SCREENHEIGHT / 2;
	double DirectionX;
	double DirectionY;
	static double CurrentRotationY = 0.0;

	SDL_GetMouseState(&MouseX, &MouseY);

	if(MouseX == CenterX && MouseY == CenterY)
		return;

	SDL_WarpMouse(CenterX, CenterY);

	DirectionX = (MouseX - CenterX)/9;
	DirectionY = (MouseY - CenterY)/9;
	
	CurrentRotationY += DirectionY;

	if(CurrentRotationY >= 60.0)
		CurrentRotationY = 60.0;
	else if(CurrentRotationY <= -60.0)
		CurrentRotationY = -60.0;
	else if(View.z - Position.z <= 0) 
		RotateCamera(-DirectionX, -DirectionY, 0);
	else if(View.z - Position.z > 0)
		RotateCamera(-DirectionX, DirectionY, 0);
}

Any ideas on how to fix these last coupla problems, since I don''t need to worry about the inverted mouse?

zedzeek

Jan 2, 2003 at 11:23 AM

perhaps youre seeing gimbal lock?

>>The camera is still very jerky though<<
perhaps smooth it out, see a paul nettle flipcode artcile

http://uk.geocities.com/sloppyturds/kea/kea.html
http://uk.geocities.com/sloppyturds/gotterdammerung.html

xg0blin

Jan 2, 2003 at 12:00 PM

It may be gimbal lock, but I''m not losing a degree of freedom, what is happening is that at z = 0 and z = PI, the camera will not move up and down *very far*. It still moves somewhat and is rather jerky, but I don''t think it''s gimbal lock. Thank you very much for the reply and the links though

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