Ray: Difference between revisions
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{{ | {{Map|Scripting|Data Types}} | ||
__TOC__ | |||
A Ray is a half-line, that is finite in one direction, but infinite in the other. It can be defined by a 3-D point, where the line originates from, and a direction vector, which is the direction it goes in. The direction is similar to the lookVector of [[CFrame#Properties|CFrame]]. | |||
Often, it is useful to construct a Ray at one point directed toward another. There is no [[constructor]] defined for this intent, but it can be be done as follows: | |||
== | local start = Vector3.new(...) | ||
local lookAt = Vector3.new(...) | |||
local ray = Ray.new(start, (lookAt - start).unit) | |||
The Ray | The Ray object's main purpose is to act as a basis for Ray casting. Its methods allow comparison of Ray against other 3-D points. Rays are also used in the [[FindPartOnRay (Method)|FindPartOnRay]] method of the Workspace. | ||
For example you can detect if a Ray intersects a sphere: | For example you can detect if a Ray intersects a sphere: | ||
= | function intersectsSphere(ray, position, radius) | ||
return ray:Distance(position) <= radius | |||
end | |||
{| | To check if the mouse is pointing at a sphere (even if other things are in the way): | ||
if intersectsSphere(mouse.UnitRay, sphere.Position, sphere.Size.X/2) then | |||
-- handle collision | |||
end | |||
{| class="wikitable" | |||
|+Constructors | |||
! Constructor !! Description | ! Constructor !! Description | ||
|- | |- | ||
| Ray.new('''Origin''', '''Direction''') || Creates a new Ray with given '''Origin''' and '''Direction'''. | | Ray.new(Vector3 '''Origin''', Vector3 '''Direction''') || Creates a new Ray with given '''Origin''' and '''Direction'''. | ||
|} | |} | ||
{| class="wikitable" | |||
{| | |+Methods | ||
! | ! Method !! Description | ||
|- | |- | ||
| ''Ray'':ClosestPoint(Vector3 '''point''') || Returns the closest point on the Ray to '''point'''. Note Rays are unidirectional. | | ''Ray'':ClosestPoint(Vector3 '''point''') || Returns the closest point on the Ray to '''point'''. Note Rays are unidirectional. | ||
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|} | |} | ||
== | == Properties == | ||
All of these properties are | |||
All of these properties are read-only: | |||
{| | {| class="wikitable" | ||
|+Properties | |||
! Property !! Type !! Description | ! Property !! Type !! Description | ||
|- | |- | ||
| | | ''Ray''.'''Origin''' || [[Vector3]] || The Origin position | ||
|- | |||
| ''Ray''.'''Direction''' || [[Vector3]] || The Direction vector | |||
|- | |- | ||
| | | ''Ray''.'''Unit''' || [[Ray]] || The Ray with a normalized Direction | ||
|} | |} | ||
== Limitations == | == Limitations == | ||
Technically, the length of the direction vector does not matter. However most Ray methods assume it is 1, so direction is a unit vector. As a result, you will get incorrect results if you do not make the direction a unit vector, or use Ray.Unit. | |||
== See Also == | == See Also == | ||
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*[[Vector3]] | *[[Vector3]] | ||
*[[UnitRay (Property)|UnitRay]] | *[[UnitRay (Property)|UnitRay]] | ||
[[Category:Data types]] | |||
Latest revision as of 17:55, 7 April 2012
< Scripting | Data Types
A Ray is a half-line, that is finite in one direction, but infinite in the other. It can be defined by a 3-D point, where the line originates from, and a direction vector, which is the direction it goes in. The direction is similar to the lookVector of CFrame.
Often, it is useful to construct a Ray at one point directed toward another. There is no constructor defined for this intent, but it can be be done as follows:
local start = Vector3.new(...) local lookAt = Vector3.new(...) local ray = Ray.new(start, (lookAt - start).unit)
The Ray object's main purpose is to act as a basis for Ray casting. Its methods allow comparison of Ray against other 3-D points. Rays are also used in the FindPartOnRay method of the Workspace.
For example you can detect if a Ray intersects a sphere:
function intersectsSphere(ray, position, radius)
return ray:Distance(position) <= radius
end
To check if the mouse is pointing at a sphere (even if other things are in the way):
if intersectsSphere(mouse.UnitRay, sphere.Position, sphere.Size.X/2) then
-- handle collision
end
| Constructor | Description |
|---|---|
| Ray.new(Vector3 Origin, Vector3 Direction) | Creates a new Ray with given Origin and Direction. |
| Method | Description |
|---|---|
| Ray:ClosestPoint(Vector3 point) | Returns the closest point on the Ray to point. Note Rays are unidirectional. |
| Ray:Distance(Vector3 point) | Returns the distance from point to ClosestPoint(point) |
Properties
All of these properties are read-only:
| Property | Type | Description |
|---|---|---|
| Ray.Origin | Vector3 | The Origin position |
| Ray.Direction | Vector3 | The Direction vector |
| Ray.Unit | Ray | The Ray with a normalized Direction |
Limitations
Technically, the length of the direction vector does not matter. However most Ray methods assume it is 1, so direction is a unit vector. As a result, you will get incorrect results if you do not make the direction a unit vector, or use Ray.Unit.
