AngleBetweenPoints Function Stops Working on Points that have a Height

[BlueBerryWizard]

When I set the height of a point

Jass:

PointSetHeight(point a, fixed height);

then try to use

Jass:

AngleBetweenPoints(point a, point b);

The AngleBetweenPoints function no longer works and always returns 0. :(

Why does it do this? To work around it I had to get the angle between the points before I set the height of the points. x.x

[Daelin]

This works just fine for me.

Jass:

lv_p1 = Point(0.0,0.0);
lv_p2 = Point(2.5,5.0);
UIDisplayMessage(PlayerGroupAll(), c_messageAreaSubtitle, FixedToText(AngleBetweenPoints(lv_p1,lv_p2), c_fixedPrecisionAny));
PointSetHeight(lv_p1, 3.14);
UIDisplayMessage(PlayerGroupAll(), c_messageAreaSubtitle, FixedToText(AngleBetweenPoints(lv_p1,lv_p2), c_fixedPrecisionAny));
PointSetHeight(lv_p2, 7.12);
UIDisplayMessage(PlayerGroupAll(), c_messageAreaSubtitle, FixedToText(AngleBetweenPoints(lv_p1,lv_p2), c_fixedPrecisionAny));

[Dr Super Good]

Do make sure that both points you are using exist. It is very easy to accidenly lose track of references so you end up comparing a point with null (which probably would yield this behaviour).

Additionally, the function mechanics might not consider the Z demention (only X/Y) so trying to compare the angle of 2 points which only have different Z positions may result in this behaviour.

[Daelin]

It does work that way. This function places the two points in a polar coordinates system (radius and angle). The resulting system is in fact centered in the first point, and the function computes the angle coordinate of the second point (with the Z coordinates ignored upon the translation).

In 3D, the problem is obviously expanded to three dimensions - more specifically a spherical coordinate system (radius, elevation angle, and azimuth angle). Because of the two distinct angles, separate functions would be needed to compute their values, with the radius remaining the classical euclidean distance between the two (the Azimuth Angle is the same as the 2D angle).

The Wiki article on the subject is very neat, and offers much more information, including conversion formulas (just in case you need something like this for your 3D solution).