Edge Detection from Mouse

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#1

I need to detect and edge of a part from the mouse position, how would I go about doing that exactly, here is a reference image.

edge
edge1128Ă—840 299 KB

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#3

Raycasting would problably get u there.

Every time a player moves there mouse u could make a ray and if the ray hits the edge of the part u could do whatever u want.

#4

Yeah but im asking how do I calculate it, there is no function for getting the edge.

#5

Using rays?, if the ray hits the edge then u could say whatever u want?

#6

The ray doesnt know if the edge is hit, it only returns what it hit and the position and the surface normal

#8

So if the ray hits the position of the edge then u could do whatever u want…

The ray will stay active until it hits the edge of the position u want it to hit

#9

Yeah but I would have to have a part at every edge, which is not the way I want to do it…

#10

No, put a part at the edge and measure the position then delete it, in ur script say if the ray hits the position the part was at then so on…

#11

Thats still very inefficient because if I have parts that are not the same size illl have to do that for every single part, also I doubt that would work properly

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#12

Duplicate the parts?, just scale it to your needs then if the ray hits the position the part was at then so on…

#13

I dont think your understanding what Im trying to achieve, basically I want to get the edge of a part from my mouse position without the need of making parts

#14

@ThoseNamesAreGood Raycasting will help, but not without the use of the surface normal. You can use the surface normal returned to determine the corner.

#15

Hm, could you explain further please

#16

The normal is a vector perpendicular to the tangential surface returned during a raycast operation. For example, (0, 1, 0) is an up vector, (0, -1, 0) is a down vector. You can use the returned normal to get an angle.

#17

Alright but after that what do I do with that angle?

#18

You want to detect the edge, so you can use the angle to determine if the surface is an edge.

#19

Could you give an example of this at least your kinda of just throwing stuff at me

#20

I do not think you can use a normal of or deduce the angle to help figure out if you hit an edge. An edge isn’t part of a face anyways, it defines a face, so it’d be impossible to actually “hit” the edge literally. You’d need to give a range from 0 to X (like 0.01) studs away from the edge to define as the edge.

#21

Basically, if you’re trying to figure out which edge of a part a Vector3 is closest to, I would do something like this:

  1. Get the position in object space - use local localPos = Part.CFrame:ToObjectSpace(mousePosition).p for that
  2. Check the components of that vector.
  3. (for example) If localPos.X is close to Part.Size.X / 2, then you’re on the right-side face. If localPos.Y is also close to -Part.Y / 2, then you’re also on the bottom-side face. Hurray! Now you know you’re on the right-bottom edge!
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#22

This would work just fine. This way, you can set a tolerance of what is accepted as the edge and what is not.