Implementing collision physics on dash move

Welcome to the forums @slamjam29!

Looking at the code, I think what is causing the issue is you do not have a condition that moves the KinematicBody2D unless it is colliding with a wall, at least not that I can see.

I think with a little restructuring, you can handle collisions and movement in the air while still detecting wall hits. Something like this I think might work:

if (is_dashing):
	var collision = move_and_collide(motion * delta)
	
	if (is_on_floor()):
		is_dashing = true
	if (is_on_wall()):
		if collision:
			motion = motion.bounce(collision.normal)
		is_dashing = true

With the code above, the KinematicBody2D should move in the air, on the floor, and against walls, which I think is what you are looking for. What I think may be causing the issue is the collision against the wall is leading the KinematicBody2D to be in the air, which was causing it not to move.

@slamjam29 said:

@TwistedTwigleg said: Welcome to the forums @slamjam29!

Looking at the code, I think what is causing the issue is you do not have a condition that moves the KinematicBody2D unless it is colliding with a wall, at least not that I can see.

I think with a little restructuring, you can handle collisions and movement in the air while still detecting wall hits. Something like this I think might work:

if (is_dashing):
	var collision = move_and_collide(motion * delta)
	
	if (is_on_floor()):
		is_dashing = true
	if (is_on_wall()):
		if collision:
			motion = motion.bounce(collision.normal)
		is_dashing = true

With the code above, the KinematicBody2D should move in the air, on the floor, and against walls, which I think is what you are looking for. What I think may be causing the issue is the collision against the wall is leading the KinematicBody2D to be in the air, which was causing it not to move.

The problem isn't the dash itself not working at all, it does detect the walls and floor. It's just the dash doesn't interact with the walls and floor beyond simply either stopping in place or sliding up and down them, when I'm trying to make the KinematicBody2D bounce around like a rubber ball. The suggestion doesn't really help much with that either. Should I post the func physics_process here as well to help with this?

Oh okay! So its not movement but collision response then. It works fine up until hitting a wall or floor, correct?

Do you have scaled RigidBody2D or StaticBody2D nodes? If so, are they scaled uniformly? Godot in 3D gives skewed normal results if the physics node does not have a uniform scale. KidsCanCode has an old article that seems to show the same effect in 2D with skewed normals, so it may be that it is still present in 2D physics.

Looking at code online, it looks like the code you are using should work.

@slamjam29 said:

@TwistedTwigleg said: No, using KinematicBody2D nodes should be fine. What I was asking is whether the KinematicBody2D nodes have a scale applied to them that is non uniform (X != Y), as sometimes that can cause issues with the physics engine in 3D, so I have a hunch that 2D may also have issues with non-uniform scaled objects.

I'm sorry, I'm a bit new to all of this and now I'm a bit lost here. How exactly do you look for non-uniform scaled objects?

No worries! A non-uniform scaled object is an object whose scale on one axis is different than the other. Here's some example values:

vector2(1, 1) # uniform
vector2(0.5, 1) # non-uniform
vector2(4, 4) # scaled but uniform
vector2(3, 4) # scaled but non-uniform

You can check whether a node has a uniform scale or not by clicking the node in the Godot editor and checking the scale property. If the X and Y values are the same, then it has a uniform local scale. Generally, the local scale is all you need to check, but if the node's parent is scaled, then you will want to check it as well to see if the parent node's scale is uniform as it affects the global scale of the node.

@slamjam29 said:

@TwistedTwigleg said:

No worries! A non-uniform scaled object is an object whose scale on one axis is different than the other. Here's some example values:

vector2(1, 1) # uniform
vector2(0.5, 1) # non-uniform
vector2(4, 4) # scaled but uniform
vector2(3, 4) # scaled but non-uniform

You can check whether a node has a uniform scale or not by clicking the node in the Godot editor and checking the scale property. If the X and Y values are the same, then it has a uniform local scale. Generally, the local scale is all you need to check, but if the node's parent is scaled, then you will want to check it as well to see if the parent node's scale is uniform as it affects the global scale of the node.

So I'm assuming that's in the "transform" section, correct? I checked that and they're all (1, 1) so I don't think that's the issue.

Yup, its in the transform section. Okay, so if everything is (1, 1) then its something else.

The next thing I'd probably recommend trying is seeing if setting the motion is working by simply modifying it. That can help determine if the conditions are part of the issue or not. I'd probably try flipping motion on a wall hit:

	if (is_on_wall()):
		var collision = move_and_collide(motion * delta)
		if collision:
			#motion = motion.bounce(collision.normal)
			
			# For testing, just flip motion so it goes the other way.
			# If this works, then the line above may be the issue.
			motion = -motion
		
		is_dashing = true

@slamjam29 said:

@TwistedTwigleg said:

Yup, its in the transform section. Okay, so if everything is (1, 1) then its something else.

The next thing I'd probably recommend trying is seeing if setting the motion is working by simply modifying it. That can help determine if the conditions are part of the issue or not. I'd probably try flipping motion on a wall hit:

	if (is_on_wall()):
		var collision = move_and_collide(motion * delta)
		if collision:
			#motion = motion.bounce(collision.normal)
			
			# For testing, just flip motion so it goes the other way.
			# If this works, then the line above may be the issue.
			motion = -motion
		
		is_dashing = true

I tried it and the dash seems completely unaffected. So it seems like the problem is with the conditions itself, but the question is how do I fix this?

What I would recommend in this case is to add print statements around key points in the code. The first I would add is one that prints is_on_wall to see if it ever becomes true. What I would do is add the statement after if (is_on_wall()): so the console isn't spammed with print statements. If is_on_wall is returning true, then I would delete that print statement and add one that prints collision to see what it returns.

Its slow and tedious, but I have found selectively printing the data you are working with can be a good way to narrow down exactly what part of the code is not working, especially with collisions.