Should lose momentum when hitting walls or ceilings

[Skaruts]

There are some undesirable behaviors caused by movement momentum not being lost when hitting walls or ceilings:

• if you move into a wall that is low enough to jump over it, and release the forward key and jump right after, you'll be propelled forward onto the wall due to the leftover momentum

  • this will also cut the jump short (as short as the wall), which is also undesirable

• when jumping and hitting a low ceiling, you'll remain in the air for as long as it takes for the jump momentum to wear out, instead of falling as soon as you hit the ceiling

[mrezai]

These issues could be fixed but are out of scope of this project to keep code simple as possible.
Based on Godot documents maybe someone can change current implementation to achieve desired behavior:
Modifies velocity if a slide collision occurred. To get the latest collision call get_last_slide_collision(), for more detailed information about collisions that occurred, use get_slide_collision().

this will also cut the jump short (as short as the wall), which is also undesirable

You can use these parameters to tweak current behavior:
https://github.com/mrezai/GodotStairs/blob/master/Player/Player.gd#L33-L34

[Skaruts]

I'm not entirely sure of what I'm doing, but seems like this is working. I added it after move_and_slide.

var coll := get_last_slide_collision()
if coll:
	var normal := coll.get_normal(0) 
	if is_in_air:
		# if bumping on ceiling
		if gravity_direction.y >= 0 and normal.dot(Vector3.DOWN) > 0:
			gravity_direction.y = 0
		# if bumping on a wall
		elif normal.dot(main_velocity) < 0:
			main_velocity = main_velocity.slide(normal)

I suppose I should be checking for all the collisions in a loop, instead of just one, but so far this seems to be resulting in the behaviors I wanted.

I didn't make any changes to SPEED_CLAMP_AFTER_JUMP_COEFFICIENT or SPEED_CLAMP_SLOPE_STEP_UP_COEFFICIENT, as that didn't seem make any difference to the behavior.

[mrezai]

Thanks for sharing your solution, maybe someone will find it useful.

I didn't make any changes to SPEED_CLAMP_AFTER_JUMP_COEFFICIENT or SPEED_CLAMP_SLOPE_STEP_UP_COEFFICIENT, as that didn't seem make any difference to the behavior.

You can change is_enabled_stair_stepping_in_air flag to see difference.

[Skaruts]

No problem. :)

Here's my updated version, where I test all the collisions that might happen:

var coll := get_last_slide_collision()
if coll:
    var normal:Vector3
    var last_normal:Vector3

    for i:int in coll.get_collision_count():
        normal = coll.get_normal(i)

        # if this collision's normal is the same, no need to test it
        if normal == last_normal:
            continue

        last_normal = normal
        
        if is_in_air:
            # if bumping on a ceiling
            if gravity_direction.y >= 0 and normal.dot(Vector3.DOWN) > 0:
                gravity_direction.y = 0
            # if bumping on a wall
            if normal.dot(main_velocity) < 0:
                main_velocity = main_velocity.slide(normal)

[Skaruts]

There's an issue in my code, though. The part where I detect if I'm bumping on a wall, sometimes makes is_on_floor() start alternating between true and false every frame. That will make it unresponsive to the jump key and movement becomes a little floaty.

I'm not sure why it happens, but it may be because the way I'm detecting walls may also be true when hitting the floor. Not sure how to fix that...

EDIT: since the floor is always below the player, I check if the collision happened above the base of the player, but the issue still remains. It's probably caused by sliding the main_velocity. I don't know what else I could do there.

If I change the velocity to zero, to fix that issue with momentum, I'll then get stuck on walls whenever I jump. I added the slide to prevent that, but it seems to be the cause of this issue. I'm clueless now...

[Skaruts]

I just realized all the code above could've been greatly simplified like this:

if is_on_wall_only():
    main_velocity = main_velocity.slide(get_wall_normal())
elif is_on_ceiling():
    gravity_direction.y = 0

---

Anyway, I found the issue I'm having, but not the solution yet...

The part where I detect if I'm bumping on a wall, sometimes makes is_on_floor() start alternating between true and false every frame.

The reason I'm having that bug is because gravity is being reset to zero whenever is_on_floor() is true. If I always apply a bit of gravity (which is what people usually do), then the bug is gone, but... it disrupts the stairs algorithm.

if is_on_floor():
    (...)
    gravity_direction = Vector3.DOWN * gravity * delta     # can't do += here or it will accumulate as if you're falling
else:
    (...)
    gravity_direction += Vector3.DOWN * gravity * delta