Do you mean raycasting?
Example
//this checks for colliion between an object with any other object and returns its id
width#=(GetObjectSizeMaxX(object)-GetObjectSizeMinX(object))/2
height#=(GetObjectSizeMaxY(object)-GetObjectSizeMinY(object))/2
depth#=(GetObjectSizeMaxZ(object)-GetObjectSizeMinZ(object))/2
x#=getObjectX(object)
y#=GetObjectY(object)
z#=getObjectZ(object)
// calculate the start of the ray cast
start_x# = x#-width#
start_y# = y#+height#
start_z# = z#-depth#
// calculate the end of the ray cast
end_x# = x#+width#
end_y# = y#-height#
end_z# = z#+depth#
// determine which object has been hit
object_hit = ObjectRayCast(0,start_x#,start_y#,start_z#,end_x#,end_y#,end_z#)
There is alsorts of raycasting commands that basically cast a ray through an object to see if there is a collision
there is even
ObjectSphereSlide( objID, oldx, oldy, oldz, newx, newy, newz, radius ) which may be used for sliding collisions
for some reason the code tags don't seem to want to work
fubar