the angle from point A to point B (where the mouse is)

[Jon Moyles]

i'm trying to figure out the angle between a point in my sceane and the
point at which the mouse has been clicked. i've been looking at 3dD
world ([url]http://www.dmu.com/[/url]) but my maths skills arent strong enough to
figure it out from the starting point that gives me.

so i have something like:

mousePlace = the mouseLoc - point(sprite(1).left, sprite(1).top)

tRollOverModel = sprite(1).camera.modelUnderLoc(mousePlace)

if tRollOverModel <> 0 and _mouse.mouseDown then
targ = sprite(1).camera.spriteSpaceToWorldSpace(mousePlac e)
put "mouseover " & targ
end if

this tells me if ive clicked on the model and gives me "a" reading on
where the mouse is. i want to rotate a model to point at where the mouse
is.

any help would be much apreciated.

jon

[walfridson]

Check out pointat()
and if you need, anglebetween()

[juroo]

so, time for a little math :)

A, B -> points
v = B-A ->vector from A to B
vx -> x axis
alpha -> angle between v and vx

v . vx
--------- = cos alpha
|v| . |vx|

[Jon Moyles]

thanks guys

i havent solved it yet though. i apologise for my ignorance.

heres whats going on. i have a pendulum hanging in my sceane, i want to
point the pendulum towards a mouse click (and then have it swing, the
swinging part works fine). pointing it at a mouse click is proving a lot
harder.

i want the pendulum to only move on one plane (it rotates on its x axis).

heres what i'm trying to do. i find the place where the user has clicked
(targ) i find the location of the fulcrum (fulcrumLoc) and i find the
location of the camera (cameraLoc). then i try to get the angle from the
fulcrumLoc to the point on the sightLine (targ - cameraLoc) on the yz
plane (where to turn the pendumlum to point at the mouse).

mousePlace = the mouseLoc - point(sprite(1).left, sprite(1).top)
cameraLoc = sprite(1).camera.worldPosition
fulcrumLoc = member("pendulum04").model("fulcrum01").worldPosit ion
targ = sprite(1).camera.spriteSpaceToWorldSpace(mousePlac e)
sightLine = targ - cameraLoc
pendulumAngle =
member("pendulum04").model("fulcrum01").transform. position.angleBetween(sightLine)


as you can see i dont know what i'm doing. for one thing i dont know how
to work on a point in the yz plane. for another
transform.position.angleBetween is throwing a "method not found" error.
So i still need help. I apreciate the efforts already made and would
really like it if somebody can explain what i'm doing wrong.

thanks
jon