Cast ray relative to the direction my Object is moving

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Hello, I want to cast a ray to the floor to detect what type of road my car is riding on. I tried something like this: Vector3 direction = -transform.up + new Vector3(1, 0, 0) (because I want my direction to be a little "tilted", not perfectly perpendicular with the road), but if my object is moving from an opposite direction the ray will be wrong; I would need something like Vector3 direction = -transform.up + new Vector3(-1, 0, 0).

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The same problem if I want my ray to always point to the left of my object. I'm pretty sure this is something relative to the front direction of my object and a cross product, but I can't find the exact solution.

Answer 1

Answer by Taylor-Libonati · Apr 09, 2019 at 09:12 PM

Instead of hard coding a vector you need to get the direction the car is already moving. Luckily there is a handy function for that. You can do something like this:

 Vector3 carForward = transform.forward; //Get the direction the transform is facing
 carForward.y = 0;//Ignore the y because you don't want that to influence the height
 Vector3 direction = -transform.up + carForward;
 direction = direction.Normalized() * distanceToCheck; //OPTIONAL: I suggest normalizing and multiplying so that you can control how far you want this check to go

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gabelu979 · Apr 09, 2019 at 10:56 PM 0

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Thanks a lot! In the third line, by forwardDir, did you mean the carForward declared above?

Taylor-Libonati gabelu979 · Apr 10, 2019 at 05:00 PM 0

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Yup! I sure did.

Taylor-Libonati gabelu979 · Apr 10, 2019 at 05:04 PM 0

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I edited my answer to reflect this. Glad it helped!

Cast ray relative to the direction my Object is moving

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