Calculate Angles (in LDCad)

[Roland Melkert]

There's another way to do this, by finding the intersection of two circles. This might be handy if you need to do it in a program that doesn't have LDCad's triangle calculation feature (or if, as I did, you forgot that feature exists and spent an hour figuring it out for yourself and are feeling all clever about it). 

I setup the selection info stuff before the scripting existed and didn't want to force a certain way to apply the angles etc.

But you could script your method, and apply the angles in one go if wanted.

FYI: This is what the selection info does internally:

Code:

       
const double a=relPnt[0].length(relPnt[1]);
const double b=relPnt[1].length(relPnt[2]);
const double c=relPnt[2].length(relPnt[3]);

const double angAB=rad2Deg(acos((a*a+b*b-c*c)/(2*a*b)));
const double angBC=rad2Deg(acos((b*b+c*c-a*a)/(2*b*c)));

TGLVector3d BADir=relPnt[0]-relPnt[1];
BADir.normalize();
TGLVector3d BCDir=relPnt[2]-relPnt[1];
BCDir.normalize();
TGLVector3d CBDir=BCDir*-1.0;
TGLVector3d CDDir=relPnt[3]-relPnt[2];
CDDir.normalize();

TGLVector3d planeNor(true);
planeNor.comp[sCompIdx]=1.0;

const double intAngAB=rad2Deg(planeNor.calcSignedAngleBetween(BCDir, BADir));
const double intAngBC=rad2Deg(planeNor.calcSignedAngleBetween(CBDir, CDDir));

const double angABCor=intAngAB+angAB;
const double angBCCor=intAngBC-angBC;

const double angABCorInv=intAngAB-angAB;
const double angBCCorInv=intAngBC+angBC;