Planet Chili

I can't figure out how to code a function that returns the direction (in degrees 0=right 90=up 180=right 270=down) between two points.

Example:

int point_direction(x1,y1,x2,y2);

point_direction(0,0,180,0)=90

I need it so bad

If "0=right 90=up 180=right 270=down", why should "point_direction(0,0,180,0)=90"??

It should be "point_direction(0,0,180,0)=0".

Not sure if Chili's answer nail'd it, but you could always use tan(alpha)=(y2-y1)/(x2-x1), if I still remember that one correctly.

Yeah, my post wasn't so much an answer as it was just a confirmation because he seems to be contradicting himself in his question there.

You are right LuX in that that is the math he will need to use, although he'll have to massage it a bit to get it into C code.

Sorry, it was late and I was tired.

I found it btw

int Game::point_direction(int x1, int y1, int x2, int y2)
{
return((int)(atan2((float)y2-(float)y1,(float)x2-(float)x1)*180 / PI));
}

edit: nvm

You got it KPence, good job. I will just add my two cents here and recommend that you consider using radians instead of degrees when programming. Radians are the units used by the functions in the libraries, so if you insist on working in degrees you will be constantly converting between the two. This will introduce unnecessary calculations into your code degrading the performance of your programs.

I know degrees just feel more familiar and easier to conceptualize, but once you learn to think in radians, it will make a bunch of other math that much easier to understand. The training wheels have to come off sometime bro. Let me put it this way: if you can't get your head around radians, don't even THINK about attempting to learn 3D graphics.

Anyways, here is how I would write your function to return radians in float:
And here it is returning degrees in int: