How do I use collision masks?

Gamero

I have a robot, that is a CharacterBody3D, with a RayCast3D attached.
I have walls, that are 3d staticbodies.
I have pickups, that are 3d staticbodies.
I want the robot to collide with the walls, but not the pickups.
I want the raycast to collide with walls and the pickups.
I assumed that I should put the robot and walls in layer 1 and collisionmask to layer 1, the pickups in layer 2 and collisionmask to layer 2, and set the raycast collisionmask to both layers.
Thats not working, the rays collide with walls but not pickups.
How do I do this?

Jesusemora

Gamero I have pickups, that are 3d staticbodies.

no. static bodies are static. use them for the world.
for pickups use either RigidBody3D or Area3D

Gamero I want the robot to collide with the walls, but not the pickups.
I want the raycast to collide with walls and the pickups.
I assumed that I should put the robot and walls in layer 1 and collisionmask to layer 1, the pickups in layer 2 and collisionmask to layer 2, and set the raycast collisionmask to both layers.
Thats not working, the rays collide with walls but not pickups.
How do I do this?

world on layer 1, collide with doesn't matter
player on layer 2, collide with layer 1 (this means it can walk and hit walls)
pickups on layer 3, (collide with layer 4?). collide with layer 2 will make them be moved by the player but the player will not react to them.
raycast on layer 4, collide with layer 3. if you are using an Area3D you have to enable detect areas.

DaveTheCoder

An approach I've used:

For each type of object:

Specify its collision layer as a power of 2:
object type A: layer 1
object type B: layer 2
object type C: layer 4
object type D: layer 8
object type E: layer 16

Specify its collision mask as the sum of the collision layers of the object types with which it can collide:
object type A: mask 2 + 16 = 18 (can collide with object types B and E)
object type B: mask 1 + 8 = 9 (can collide with object types A and D)
object type C: mask 4 (can collide with object type C)
object type D: mask 2 (can collide with object type B)
object type E: mask 1 (can collide with object type A)

I haven't used raycasts (successfully). I don't know if they handle collisions differently than other nodes.

Gamero

Jesusemora

Cant get it to work. I tried setting up 4 layers like you wrote, and changed the pickups to area3ds, and set the raycast to detect areas.
As soon as I turn off layer 1 for the pickups, the raycast stops detecting them.

Here is how I set up the pickups (scraps)
`SetCollisionLayerValue(tacticalScene.COLLISION_LAYER_STATIC, false);
SetCollisionLayerValue(tacticalScene.COLLISION_LAYER_DRONE, false);
SetCollisionLayerValue(tacticalScene.COLLISION_LAYER_SCRAP, true);
SetCollisionLayerValue(tacticalScene.COLLISION_LAYER_RAYCAST, false);

SetCollisionMaskValue(tacticalScene.COLLISION_LAYER_STATIC, false);
SetCollisionMaskValue(tacticalScene.COLLISION_LAYER_DRONE, false);
SetCollisionMaskValue(tacticalScene.COLLISION_LAYER_SCRAP, false);
SetCollisionMaskValue(tacticalScene.COLLISION_LAYER_RAYCAST, true);`

and I set up the raycast like this
rayCast.SetCollisionMaskValue(tacticalScene.COLLISION_LAYER_STATIC, true); rayCast.SetCollisionMaskValue(tacticalScene.COLLISION_LAYER_DRONE, true); rayCast.SetCollisionMaskValue(tacticalScene.COLLISION_LAYER_SCRAP, true); rayCast.SetCollisionMaskValue(tacticalScene.COLLISION_LAYER_RAYCAST, true);

Any help debugging this is appreciated.

trizZzle

Gamero If you print your raycast mask value, what does it show?

Jesusemora

Gamero this is from my own project:
RAYCAST

AREA2D

Gamero As soon as I turn off layer 1 for the pickups, the raycast stops detecting them.

don't change this in code 😞

collision layer is the layer the object is in. collide with/mask is the objects it will collide with.
if player is in layer 2, world in layer 1, and a ball in layer 3. if the ball has collide with layer 2 and layer 1, it will be stopped by the walls and floor and moved by the player. but player has collide with layer 1 only, so it will not react to the ball.

Gamero

trizZzle RayCast Mask: 15

@Jesusemora All of the nodes are procedurally generated, so I think I have to set it in code.
Thanks for the clarification of how the layers work. It is how I suspected it works, but I was not certain.