Vector from camera to X axis

[Alexey Vanzhula]

I have origin and direction (perpendicular to camera) from mouse pointer.

I want to transform the direction somehow to intersect it with global X axis. 

http://i.imgur.com/tr7s0I4.png

[Alexey Vanzhula]

It works well for free moving in screen space with using of dot product. But I dont understand how to transform the mouse pointer direction to X or any other axis...

 

Another simple example of what i want to get
https://youtu.be/UlRcRHgyAwY

Edited August 26, 2015 by Alexey Vanzhula

[MrScienceOfficer]

Maybe I misunderstand, but it sounds like your just overthinking it.

 

What I would do is snap the object to the corresponding axis.  i.e. project from camera origin by camera direction at the XY plane, then set Y to zero.  Thus it sticks flat to the Y axis, and is projected at the X axis.

[Alexey Vanzhula]

Thanx for the right direction 

So, my solution is:
 

1. Move in XY plane

 

P = p - d * (dot(p - p1, n) / dot(d, n))

Where:

  p - pointer position

  d - pointer direction
  p1 - position of plane normal

  n - normal to plane

2. Then set Y to 0 if need

Edited August 27, 2015 by Alexey Vanzhula

[MrScienceOfficer]

Yeah, that looks about right.  Might be p+d*scalar though

 

And to nitpick a little more, I should have said intersect with XY plane, not project.  intuitively projection sounds right but its not the same. 

[Alexey Vanzhula]

And to nitpick a little more, I should have said intersect with XY plane, not project.  intuitively projection sounds right but its not the same

 

Yes, but it works as I need

Edited August 27, 2015 by Alexey Vanzhula

[Alexey Vanzhula]

p+d*scalar

 

yes, it is