Thread: Helm, plot out a course to the gamma system...

Heres a function snippet straight from an old game. There are a couple custom Macros which you'll have to replace with something equivelant. The Macro names will indicate precisely what they do. I'm not sure its the best implimentaion (as I mentioned, its an old game of mine) but I'm fairly sure it works. It should rotate your source object an "Amount" closer to your target in the closest direction to rotate in. Code Warrantee: As Is.

Code:

C3DEntity & C3DEntity::PlanarLookAt(const D3DXVECTOR3 lookatPoint, float Amount)
{
	float
		RealXTarget = lookatPoint.x - x,	//x is this objects x coordinate
		RealZTarget = lookatPoint.z - z,	//z is this objects z coordinate
		destRot = fRot,					//fRot if this objects Rotion in Radians
		Rd,
		Ld;

	//Get the Effects Rotation value based on its trajectory
	if (RealZTarget != 0.0f)
	{
		destRot = float( atan(RealXTarget / -RealZTarget) );
		if (RealZTarget < 0.0f)
			destRot += _MATH_PI;
	}
	else
	{
		if (RealXTarget < 0.0f)
			destRot = 1.5707f; //Hardcoded for speed //DegreesToRadians(90.0f);
		else
			destRot = 4.7122f; //Hardcoded for speed //DegreesToRadians(270.0f);
	}

	//determine which direction to rotate
	if (fRot > destRot)
	{
		Rd = fRot - destRot;
		Ld = (destRot + 3.14f) - fRot;
	}
	else
	{
		Rd = (destRot + 3.14f) - fRot;
		Ld = fRot - destRot;
	}

	//Make sure Ld is posative
	POSATIVE(Ld);

	//Rotate in the closest direction
	if (Rd < Ld)
	{
		PlanarRotate(-Amount);
		if (fRot < destRot)
			fRot = destRot;
	}
	else
	{
		PlanarRotate(Amount);
		if (fRot > destRot)
			fRot = destRot;
	}

	return (*this);
}

Originally Posted by Bubba

That only rotates around the y axis correct? Essentially in an airplane this would be yaw. I don't see anything for other axes.

Correct. This code isn't valid in a 3D enviroment. For some reason when I read "ship" I assumed sailng ship or whatnot in a 2D game, not a flying craft in a 3D one. Rotating in a 3D envirment using Pitch, Yaw, and Roll is more irritating. Better to use vectors in that case. However, the code given could be expanded to work in a 3D enviroment by applying a second pass with it to cover the other axis.