TypeFunction ObjectParticleSystem Libraryphysics.* Return valueArray RevisionRelease 2021.3646 KeywordsrayCast, physics, LiquidFun See alsophysics.newParticleSystem() object:queryRegion()

This function is used to find the particles that collide with a line. It returns an array of tables describing each hit.

If the starting position is inside a particle, no hit will be registered for that particle.

ParticleSystem:rayCast( from_x, from_y, to_x, to_y, behavior )

*Number.* The starting **x** position of the ray.

*Number.* The starting **y** position of the ray.

*Number.* The ending **x** position of the ray.

*Number.* The ending **y** position of the ray.

*String.* The collision test behavior, in increasing order of performance cost:

`"any"`

— Return one result, but not necessarily the closest one.`"closest"`

— Return only the closest hit from the starting point, if any. This is the default behavior.`"unsorted"`

— Return all results in no particular order.`"sorted"`

— Return all results, sorted from closest to farthest.

`hits`

will be an array of elements containing these properties:

`x`

— The**x**collision position in content space.`y`

— The**y**collision position in content space.`normal.x`

— The**x**component of the normal of the surface hit in local space.`normal.y`

— The**y**component of the normal of the surface hit in local space.`fraction`

— The fraction (`0`

..`1`

) along the ray where the hit is located.`0`

is the start point of the ray cast and`1`

is the end point.

local hits = ParticleSystem:rayCast( 0, 0, 200, 300, "closest" ) if ( hits ) then -- There's at least one hit print( "Hit count: " .. tostring( #hits ) ) -- Output the results for i,v in ipairs( hits ) do print( "Hit: ", i, " Position: ", v.x, v.y, " Surface normal: ", v.normal.x, v.normal.y ) end print( "The first particle hit at position: ", hits[1].position.x, hits[1].position.y, " where the surface normal is: ", hits[1].normal.x, hits[1].normal.y, " and where the fraction along the ray is: ", hits[1].fraction ) else -- No hits on raycast end