# Rotating planes so that one rotationaxis is set to zero

Hello everybody,

I'm fairly new to maxscript but I have some experience with c and java.

My Problem:

Within my scenes there are planes that are placed and rotated by hand. The person who placed them now needs two values from those planes: heading and the pitch

To be more precise: The Values for pitch (or drop as it's an tectonically problem) need to be between 0-90 degrees

The Values for heading need to be between 0-360 degrees. (both eulerangles)

I don't actually need to rotate those planes in the end but I really need those values.

My solution so far:

I don't know if there is an easier way to do this in maxscript. So please point out any stupid stuff I'm doing.

1. collect all planes in the scene and convert them to poly with only one face

2. get normal vector for each plane (normalvector = polyOp.getFaceNormal 1)

3. get the "horizontal" vector for that plane (horizontalVector = normalize (cross [0,0,1] normalvector))

4. get the "vertical" vector (verticalVector = normalize (cross horizontalVector normalvector ))

5. get the vector facing to the front (frontVector = normalize ([normalvector [1], normalvector [2], 0]))

6. after all that I calculate the angle between the vertical vector and the front vector with (theAngle = acos(dot (normalize frontVector ) (normalize verticalVector )))

All the results till now were really strange. In some cases I looked like it worked correctly and in others it really wasn't right at all.

Am I missing something here? Am I using the right approach to this problem?

I can't provide any working code right now because of some strange bug in maxscript. Nevertheless would I be very thankful if anyone has an idea how this could be solved?

If you need any more code I will happily post any "non-working" snippets ;-)

Cheers,

Per

## Comments

## Heading of the drop?

That's exactly what my snippet finds. Did you try it?

Make a plane, rotate it randomly and run the code. Then check the result.

Note that the angle follows the usual convention, i.e. 0° points towards positive X and positive angles are CCW.

## I tried your code but my

I tried your code but my results weren't right.

Nevertheless I found a solution my self. Thank you anyway.

Here is my final code:

## and one more thing...

I'm not looking for the actual object heading (the sections(planes) are randomly placed by hand). I just need the heading of the drop. hopefully that helps a little understanding the problem.

## Hi,

this is what i've got so far:

and I'm using the following script to generate my test enviroment:

As you can see I implemented your samples and now all my drop angles are correct. Thank you very much for that! But ;-) ...my heading is still messed up. It seems if it is giving me less than half the time correct results and the rest is just screwed up.

What am I missing here guys?

Both the atan2 and the acos(dot v1 v2) solutions aren't working correctly.

Thanks in advance for all your help.

## hi

hi fexed , the garp 's solution is right and

work with face normal as well ( just have to convert negative angle in positive value )

i just want to give you a small advice

when you work with maxscript, dont hesitate to create small interface to check

your resutt in real time

quick new script a couple of output field

a timer then you could see really well what s happen in your test case

cut and paste when everithing s fine

obviously your calculation was bad :)

sorry

example :

north = [0,1,0]

rollout unnamedRollout "Untitled" width:388 height:265

(

Timer tmr1 "Timer" pos:[328,220] width:24 height:24 interval:100

edittext drop "" pos:[72,30] width:125 height:22

edittext dir "" pos:[72,75] width:125 height:22

on tmr1 tick do

(

if $ == undefined do return false

nv = polyOp.getFaceNormal $ 1

heading = (atan2 nv.y nv.x )

dropt = acos ( dot nv z_axis )

drop.text = ( dropt as string )

dir.text= ( heading as string )

)

)

createdialog unnamedRollout

shanghalf

## If I understand correctly...

You don't need to convert to anything.

These angles correspond to the pivot, not the geometry. If the pivot has been rotated independently of the object, you need a face normal.

## Hi again, two things that

Hi again,

two things that I've come up with so far.

First I simplified my code a lot:

And second I created a testing setup here:

So what I need now are drop angles between 0-90 degrees and heading angles between 0 and 360 degrees. But what I get are angles between 0 and 180 degrees that are obviously not correct.

Could anybody help me with that? I'm really stuck right now.