Take a look on at the image on the right.I need to find y and x distances between two dots (points) that lie on this plane i know the y and x directions and the points poisition, surface normal is also known.

I need this to find angle between these two points (and i need it to e between 0..360) maybe someone knows better formula to achieve this.

Adding to Brother Bob's post (thumbs up):

You can't determine an angle between two points. An angle would be between two lines or vectors. You haven't provided enough information to determine what "angle" you're looking for.

Brother Bob:

Project the vector between the two points onto the X and Y vectors. Just ensure that the X and Y vectors are normalized.

The projections are the component along the X and Y directions, respectively - ? you mean after projection i take the vector length? X len = veclength(Xvec* Projected(B-A))

I will take a guess that you don't need the angle, but rather that you want the angle because you don't know a solution in linear algebra. You have a vector-based problem, and solutions rarely involve angles. Describe your problem instead and we'll propose a vector solution that isn't dependent on angles.

Brrrrp wrong i need to output the angle after getting this new x y

Buckeye

Oh indeed i can

template <class type> long double __fastcall GetLongitudeLD(t3dpoint<type> cpos, t3dpoint<type> pos)   //poludniki (Dlugosc)
{
 long double       angle;
 angle = n2dGetPolarCoordAngleAD((long double)cpos.x-(long double)pos.x,(long double)cpos.z-(long double)pos.z) / (pild*2.0);
		//

angle = -360.0*angle;
angle = VALIDUJ(angle)+90.0; //this may show the error since i copied wrong function that required 90 degree rotation in order to get proper angles
angle = VALIDUJ(angle);
	   return angle;


}

long double __fastcall n2dGetPolarCoordAngleAD(double x,double y)
{
if ( (x == 0) && (y > 0) )  { 	return 3.1415926535897932384626433832795/2.0;                   }

if ( (x == 0) && (y < 0) )  { 	return 3.0*3.1415926535897932384626433832795/2.0;                 }

if (x == 0) return - 1000.0;
long double k; k = (long double)y / (long double)x;
if ( (x > 0) && (y >= 0) ) { 	return atanl(k);        }

if ( (x > 0) && (y < 0) )  { 	return atanl(k)+2.0*3.1415926535897932384626433832795;  	  }

if  (x < 0)                {	return atanl(k)+3.1415926535897932384626433832795;   	  }




//last versions were without .0 just simple 2 division
return - 1000.0;
}

template <class type> type __fastcall VALIDUJ(type angle2)

{
				   type angle = angle2;

int kat=(int)angle2;

kat=kat/360;

if (angle < 0 )

   {

   angle = angle + (type)(kat+1)*360.0;

   }

if (angle >= 360)

   {

   angle = angle - (type)kat*360.0;

   }



return angle;

}

where cpos is blue point position, and pos is red dot position

heres a helper drawing:

thanks