Osprey teleports to world origin if it isn't moving at all

[SamVanheer]

If a monster_osprey isn't moving at all it will teleport to the world origin due to a divide by zero error.

Change this:

halflife/dlls/osprey.cpp

Lines 415 to 424 in c7240b9

	float scale = 1.0 / m_dTime;
	float f = UTIL_SplineFraction( t * scale, 1.0 );
	Vector pos = (m_pos1 + m_vel1 * t) * (1.0 - f) + (m_pos2 - m_vel2 * (m_dTime - t)) * f;
	Vector ang = (m_ang1) * (1.0 - f) + (m_ang2) * f;
	m_velocity = m_vel1 * (1.0 - f) + m_vel2 * f;
	UTIL_SetOrigin( pev, pos );
	pev->angles = ang;

To this:

//Only update if delta time is non-zero. It's zero if we're not moving at all (usually because we have no target).
if (m_dTime != 0)
{
	float scale = 1.0 / m_dTime;

	float f = UTIL_SplineFraction(t * scale, 1.0);

	Vector pos = (m_pos1 + m_vel1 * t) * (1.0 - f) + (m_pos2 - m_vel2 * (m_dTime - t)) * f;
	Vector ang = (m_ang1) * (1.0 - f) + (m_ang2)*f;
	m_velocity = m_vel1 * (1.0 - f) + m_vel2 * f;

	UTIL_SetOrigin(pev, pos);
	pev->angles = ang;
}

This change disables the movement update logic if the time between movement positions is zero. This value is zero if the Osprey isn't moving at all, such as when it has no target or when its speed is 0. It causes the scale variable to become infinity and the calculated vectors to become not-a-number (NaN) values which results in the Osprey moving to the world origin.

This also applies to the Black Ops Osprey in Opposing Force.