Getting point between two vectors help math experts!

In a Vector3 world, I have point A and point B, and all I want to do is get point C as you can see in this image, I know it's possible but may require advanced math techniques that I don't have, The only reason I want to do this is because I want to rotate a gameobject in pont A in the direction of point B but only in his local Y axis, thanks guys!



This is the code I'm using to rotate game object in pont A in the direction of point B:

pointA.rotation = Quaternion.Slerp(
pointA.rotation,
Quaternion.LookRotation((pointB - pointA).normalized),
Time.deltaTime
);

 

Im not 100% sure, but I think you might be looking for cross...

http://docs.unity3d.com/ScriptReference/Vector3.Cross.html

 

@JamesLeeNZ Yup if you want to get point C in world space like the diagram states, you should use Cross like James has listed.

 

Maybe the ClosestPointsOnTwoLines method found here can help.
http://wiki.unity3d.com/index.php/3d_Math_functions

Ill paste it here in case the link dies

Spoiler: Click for code

Code (CSharp):

1.     public static bool ClosestPointsOnTwoLines(out Vector3 closestPointLine1, out Vector3 closestPointLine2, Vector3 linePoint1, Vector3 lineVec1, Vector3 linePoint2, Vector3 lineVec2){
2.         closestPointLine1 = Vector3.zero;
3.         closestPointLine2 = Vector3.zero;
4.         float a = Vector3.Dot(lineVec1, lineVec1);
5.         float b = Vector3.Dot(lineVec1, lineVec2);
6.         float e = Vector3.Dot(lineVec2, lineVec2);
7.         float d = a*e - b*b;
8.         //lines are not parallel
9.         if(d != 0.0f){
10.             Vector3 r = linePoint1 - linePoint2;
11.             float c = Vector3.Dot(lineVec1, r);
12.             float f = Vector3.Dot(lineVec2, r);
13.             float s = (b*f - c*e) / d;
14.             float t = (a*f - c*b) / d;
15.             closestPointLine1 = linePoint1 + lineVec1 * s;
16.             closestPointLine2 = linePoint2 + lineVec2 * t;
17.             return true;
18.         }
19.         else{
20.             return false;
21.         }
22.     }    

You may want to edit that code to instead of returning bool and using out, to just return what you want.

 

The cross product returns a vector that is perpendicular to both the vectors passed in. Not sure this will help you.

I'm struggling to see how A, B and C are related to each other...

 

http://answers.unity3d.com/questions/566152/lookat-locked-at-y-axis-but-in-local-space.html

--Eric