pan

tilt

roll

Range:

Type:

Remarks:

• Angles are given in degrees (0 to 360) and counted counter-clockwise. For rotations in three dimensions the so-called Euler angles are used: pan is the horizontal angle (0..360) about the upright Z axis, tilt is the vertical angle (-90..+90) about the rotated Y axis, and roll is the angle (0..360) about the rotated and tilted X axis (see image). For a pan angle, 0 degrees is equivalent to the positive direction of the X-axis coordinate, which points to the east of the map. 90 degrees is north, 180 degrees west, and 270 degrees south.
• By changing any of these values, the entity rotates relative to the world coordinate system. This is not the same as rotating the entity about it's own axes that may be arbitrarily tilted when the entity was rotated byfore. For rotating an entity about it's own axis, which is often required for flight or spaceship simulators, use the ang_add or ang_rotate functions.
• For orienting the entity in a certain direction or towards a certain point in space, use the vec_to_angle function.
• Angles have a special meaning with sprites. If all angles are at zero, the sprite will stand upright and horizontally face the camera. If its pan or tilt angle is nonzero, the sprite is oriented in world space according to its angles. If pan and tilt both are 0, but the roll angle is nonzero, the sprite is always perpendicular to the camera. This is useful for spherical objects, like fireballs or explosions. For an angle to be nonzero it's sufficient to set it at a small amount, like 0.01.
• Exceeding the angle ranges given above is possible. But be aware of ambiguities in entity orientation, and of 'gimbal lock' problems. If you don't know what angle ambiguities and gimbal lock problems are and how to deal with them, better do not exceed the angle limits.
• Don't change entity angles more than once per frame. This could otherwise cause problems with intermediate rotations because Euler angles are internally converted to a rotation matrix resp. a quaternion.

Example:

action rotator()
{
	while(1)
	{
		my.pan += time_step;
 		wait(1);
 	}
}

See also: