Type Function Object ParticleSystem Library physics.* Return value Array Revision Release 2022.3683 Keywords rayCast, physics, LiquidFun See also physics.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