[API Noob] How to calculate a relative angle in CPP/UE4

[Nsomnia]

@ExtraLifeMatt;527267

This should be doable, I’ll use the names you have in your image.

FVector LineOfSight = SubmarinePosition - TargetPosition;
float BowAngleInDegrees = FMath::RadiansToDegrees(Acos(FVector::DotProduct(Target.Forward, LineOfSight))); // Dot product describes the angle between Target and LineOfSight, taking the Arc Cosine gives you the actual angel in radians (0 - 2PI), we then convert that to degrees.
if (FVector::DotProduct(Target.Right, LineOfSight) < 0.0f) // We need one more dot product to actually figure out our winding
{
    BowAngleInDegrees *= -1;
}

That should give you a relative turning angle in degrees.

I will give it a try I havnt tried using the right vector 0,1,0 doesnt make sense to me in terms of trig with vectors.

I spent all night (and the past 8 days in blueprints) trying to solve this, on these/unity/coding forums, stackoverflow, looking at VictoryPlugin/Engine/C++ examples that calcultae this for open source games and could not get the proper angle… I’ve tested it from all different rotations and world locations.

Edit and correct me if I’m wrong but line of sight (line from players boat to target boat angle independant would just be the vectors multiplied right? or wouldit be the dot product so its scalar. The LoS is the range so i have that, the rotation doesnt really matter at this point that would just be targets course across my boats course sin i think opp/hyp
Just for fun I made two empty actors that are located at 0,0,0 with rotation 0,0,0 and then used every combination of atan2, acos, vector2d, cross-prod, dot-prod, up vector, forwad vector, world rotation, world location, vector multiplication/sub/add/divide (rise/run), delta rotation, find look at at rotation and no avail… they tell me the rotation is 137 degrees… It should be 0 or 180 or 360 since they are the exact same…

I’ve got this saved offline for testing later should be able to figureit out math - Direction of two points - Stack Overflow

Its quite embarressing that I can calculate all the angles needed for fire control with 3 moving targets except a core essential one, this one. Infuriating haha.