How To Create A Ledge Grabbing Mechanic In Unity
Running, jumping, wall jumps, and now “Ledge Grabs”. These are all movement mechanics that can help the game feel more alive and interactable. Running is pretty basic and easy. Jumping is a little more complex as you have to incorporate physics /gravity into the equation. Wall jumps took things into a little more of a complex area with surface normals. But then there are Ledge grabs…
Grabbing a ledge may seem pretty simple and straightforward, but it’s actually pretty technical, and it may take some work to get it to look just right.
First off, I wanna say that a lot of this involves animation, and thus you will need an “Idle Hang” animation, and a “Climb Up” animation as well if you want to follow along accurately. Now you could also get a number of other transitional animations such as a “jump to hang” animation to flesh this out and make it look even better, but I will only be covering the basics for today's article.
If you do not currently have any animations of your own or don’t have the skills to throw some together, you can just check out my other article on how to download and implement free animations! https://adamwreed93.medium.com/how-to-download-and-implement-free-3d-character-animations-for-your-game-in-unity-325c202b99cf
You will also need to have a basic third-person character movement system. I will be using one that uses a “Character Controller” component. You can use my script which covers artificial gravity, jumping, moving left/right, and rotating the player accordingly.
And with that, you should be good.
Ok, now to begin you must first create an empty game object and add a “Box Collider” to it. You can create a cube to do this and make it easier to see for testing, but if you do, just make sure to turn off the mesh renderer in the end.
Stretch the collider out until it looks like a long horizontal bar/ledge that the player can hold onto. This object will be set as a child under the player and oriented to be at the point that the player's hands would be in during their “Idle Hang” animation.
And lastly, “Tag” this object “Ledge_Grab_Checker”.
Next, you’ll need to do something similar and add an empty game object with a box collider to the ledge you are wanting to grab. This is the Ledge Checker.
Make sure this collider is set to “Trigger”, AND has a “Rigidbody” component attached.
Now create a new script, I’m going to call mine “Ledge” and attach it to this new object.
Then add the script additions below to your “Player” script.
By deactivating the “Character Controller” you are able to stop the character from being affected by gravity.
Now, you’re probably wondering what the “Hand Pos” and “Stand Pos” are for. Well, these are going to be waypoint markers to help with the ledge grab “Position Snap” for the player, and the “Ending Position” that the player will be in when they climb up on top of the ledge.
To create the “Hand Pos” object, create an empty game object. Then place your player in their “Idle Hang” animation and move them to the spot on the ledge that you think looks best. Then just copy the “Transform Position” of the player game object and paste it into the “Hand Pos”.
To create the “Stand Pos” object, create an empty game object. Then, with your player’s position set to the “Hand Pos”, activate your climb up animation and note the placement of your character at the end frame. Next, duplicate your player and place your player clone in their regular “Idle” animation and on the position that the animation is ending on. Copy this player clones position and paste it into the “Stand Pos”. Then delete the player clone object.
Creating the “Stand Pos” this way may not work for you depending on if your animation has a fixed position or not. “Apply Root Motion” is a setting in the “Animator” component that will allow you to change whether your animation can move the player or not.
This is the animator component and the Parameters I used. Showing all the individual transitions would be too much but I have confidence that you can figure these out yourself. If not then I’d recommend going back and reviewing my articles on using the Animator! https://adamwreed93.medium.com/using-the-animator-to-make-enemies-explode-after-they-die-2c5a03de85af
Next, you will need to add this behavior script to your “Climb Up” animation inside of the animator.
And lastly, you gotta add these extra additions to your “Player” script.