Thread: Is the point over my ray? Confusing...

Define "not working". Also, I'm not sure what kind of degrees cos() and sin() take in input. Euler or Radians ? Your code sounds about right if we're talking about radians.

Well, comparing the x coordinate to cos ( rayrot ) makes no sense to me.

Good point.

Just a guess, and it might not be the most efficient way to solve this, but couldn't you check if the inverse tangent of y/x is greater than rayrot? Essentially, if the angle that the position vector (x,y) makes with the x axis is greater than the angle the ray makes with the x axis, then the point must be above the ray.

Of course, you'd have to be careful to make adjustments if the point or ray is not in the first quadrant.

Did anyone say 'array' ? No. We did mention a ray though.

Originally Posted by Queatrix

I am trying to detect if my point (x & y) are over my ray (rayrot).
This is the best I could come up with, but it's not working. How should I do this?

Code:

if ( x > cos ( rayrot ) * y && y > sin ( rayrot ) * x )

Ray - what ray?
A Ray consists of a point and a direction, where the direction would normally be a vector. However this 'rayrot' seems to be just a single value, therefore it is just an angle.

The problem would however make sense, if you state that the ray happens to cross through (0, 0) for example (which I'll assume). However since you're using angles instead of vectors, you also need to state which direction an angle of zero points in. (I'll assume that increasing angle turns clockwise, and that zero is straight up, for now).

This would mean that a point (x, y) is on the ray if:

Code:

(x * cos(rayrot) == y * sin(rayrot))

However since floating point math isn't exact you'll need to use something like this:

Code:

if (fabs(x * cos(rayrot) - y * sin(rayrot) < EPSILON)

Where EPSILON is a small fraction.

Oh, I took "over" to mean "on" rather than "above".
Yes that'll do it.