This is a small post about a method for figuring out collision_line's "contact point" in GameMaker - in other words, obtaining not just whether there's something on the way, but also the nearest point on the nearest matching entity.
Most commonly asked about for "hitscan" weapons and laser-sights, but has many uses.
HaxeNME version. Love2d version works equally to this.
Click and drag different parts for interaction.
By user request on Love2d IRC channel, yesterday I've made this nice function to do intersection/collision check between a ray (for clearance, here, a ray is a infinite line with starting point but no end point) and a circle.
Underlying code is fairly simple, though it does not even require understanding to use the function.
Love2d version takes advantage of multi-return values.
Haxe version has slightly longer code due for more optimal implementation of interface.
While working with GameMaker, you might have noticed that all collision_ functions return only first instance to intersect given collision shape, while in some cases you'd want to get all instances that collide with one.
This set of simple scripts adds such missing functionality...
You might have met such situations where you need to find nearest coordinate at object's edge towards a point, or find actual (non-bounding box) distance between objects, or other things of this kind. If so, you may find this example useful.
Used method is relatively simple - first find approximate distance with distance_to_point function, and then 'fix precision' by using a 'while not position_meeting' loop.
This way maximum amount of calculations will be limited to cP * iR + dP, where
cP is time needed to check object for collision against a single point
iR is instance 'radius' (maximum distance from origin to corner of bounding box)
dP is time needed to find distance between object's bounding box and point
So it should be acceptable for many cases of usage. If you need to reduce amount of calculations further, could alter distance decrementation 'rate' in two while loops. Removing while() loops entirely would give rather approximate distance calculation.