Determine angle of a straight line in 3D space

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I have a straight line in space with an start and end point (x,y,z) and I am attempting to get the angle but I cannot figure out the formula for this. I am using VB.NET

Here is a picture of the line in my 3d environment (the one that is circled in red)

If someone can help, it would be appreciated. Again, i have the values of the start and end points (x,y,z)

It is set to an angle of 70 degrees right now.

Posted 20-Jan-15 5:48am

jk0391

Updated 20-Jan-15 7:53am

v2

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Comments

Sergey Alexandrovich Kryukov 20-Jan-15 12:43pm

Angle between what and what? If you want to get direction relative to coordinate system, this is not one angle but two.
Just learn a bit of vector algebra; if someone write some code for you, it won't help you. Do I even have to explain why?
—SA

2 solutions

Solution 1

That is a mathematical question, nothing to do with VB.NET, or any other language. As far as I recall it has something to do with the length of the sides, and sines, cosines etc.

Posted 20-Jan-15 6:00am

Richard MacCutchan

Comments

jk0391 20-Jan-15 12:34pm

Well I'd like to get the proper code to execute the formula which at the same time I am trying to find.

Richard MacCutchan 20-Jan-15 12:45pm

The code is easy once you know the formula. And Google will find that for you.

jk0391 20-Jan-15 12:55pm

Would you be able to help? I've been searching google for hours :(

Richard MacCutchan 20-Jan-15 13:04pm

Seriously? You couldn't work out https://www.google.coM/search?q=calculate+angle?

jk0391 20-Jan-15 13:38pm

It's more complicated than that. You also don't have to be rude.

Richard MacCutchan 21-Jan-15 2:59am

More complicated? Then perhaps you should make it clear in your question exactly what problem you are trying to solve. The only information you have given us is that you want to "get the angle".

jk0391 27-Jan-15 10:49am

Maybe you should read the post as I have given enough detail in there and not just my title. :) Someone was able to assist me with the exact same wording on another site.

Richard MacCutchan 27-Jan-15 11:04am

Well, I have read the post again, and it makes no more sense than it did last week. All you have said (I repeat again) is that you want to "get the angle", but what angle do you want to get? And, as I said earlier, this is a purely mathematical problem, using the lengths of the sides of the triangle and the various geometric functions. If this is not what you are trying to calculate then please edit your question and explain exactly what you are trying to do.

jk0391 27-Jan-15 11:07am

I have solved this problem as someone was able to figure it out from the information I provided. Solution is posted. :)

Richard MacCutchan 27-Jan-15 11:21am

So where is the link to the question?

jk0391 27-Jan-15 11:30am

http://stackoverflow.com/questions/28050682/determine-angle-of-a-straight-line-in-3d-space

Richard MacCutchan 27-Jan-15 12:14pm

I have a straight line in space with an start and end point (x,y,z) and I am attempting to get the angle between this vector and the plane defined by z=0. I am using VB.NET
Do you notice the information you put in the SO question that you omitted here?

jk0391 27-Jan-15 11:34am

Perhaps you might know the answer to my next question:

http://www.codeproject.com/Questions/870050/Determine-true-Axis-of-object-D-environment?arn=0

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jk0391 · Accepted Answer · 2015-01-20T07:54:00

Solution 2

VB

Dim x, y, z As Double

        x = EndPoint.X - StartPoint.X
        y = EndPoint.Y - StartPoint.Y
        z = EndPoint.Z - StartPoint.Z

        'a = arcsin(v.z / sqrt(v.x²+v.y²+v.z²))
        MsgBox((Math.Asin(z / Math.Sqrt((x ^ 2) + (y ^ 2) + (z ^ 2)))) * (180 / Math.PI))

Is the solution. Someone was kind enough to assist me on another site!

Posted 20-Jan-15 7:54am

jk0391

Comments

[no name] 20-Jan-15 15:57pm

Then it would be nice for the autrhor of the other site to give a link to it!

Richard MacCutchan 27-Jan-15 11:23am

Well that's clearly mathematics rather than programming.