Function lineSegmentSide

TheForceEngine/TFE_Polygon/polygon.cpp:317–391

	};

	PointSegSide lineSegmentSide(Vec2f p, Vec2f p0, Vec2f p1)
	{
		f32 dx = p0.x - p1.x;
		f32 dz = p0.z - p1.z;
		if (dx == 0)
		{
			if (dz > 0)
			{
				if (p.z < p1.z || p.z > p0.z || p.x > p0.x) { return PS_INSIDE; }
			}
			else
			{
				if (p.z < p0.z || p.z > p1.z || p.x > p0.x) { return PS_INSIDE; }
			}
			return (p.x == p0.x) ? PS_ON_LINE : PS_OUTSIDE;
		}
		else if (dz == 0)
		{
			if (p.z != p0.z)
			{
				// I believe this should be -1 or +1 depending on if z is less than or greater than z0.
				// Otherwise flat lines always give the same answer.
				return PS_INSIDE;
			}
			if (dx > 0)
			{
				return (p.x > p0.x) ? PS_INSIDE : (p.x < p1.x) ? PS_OUTSIDE : PS_ON_LINE;
			}
			return (p.x > p1.x) ? PS_INSIDE : (p.x < p0.x) ? PS_OUTSIDE : PS_ON_LINE;
		}
		else if (dx > 0)
		{
			if (p.x > p0.x) { return PS_INSIDE; }

			p.x -= p1.x;
			if (dz > 0)
			{
				if (p.z < p1.z || p.z > p0.z) { return PS_INSIDE; }
				p.z -= p1.z;
			}
			else
			{
				if (p.z < p0.z || p.z > p1.z) { return PS_INSIDE; }
				dz = -dz;
				p1.z -= p.z;
				p.z = p1.z;
			}
		}
		else // dx <= 0
		{
			if (p.x > p1.x) { return PS_INSIDE; }

			p.x -= p0.x;
			dx = -dx;
			if (dz > 0)
			{
				if (p.z < p1.z || p.z > p0.z) { return PS_INSIDE; }
				p0.z -= p.z;