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Attention | Topic was automatically imported from the old Question2Answer platform. |
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Asked By | nic96 |
With ChatGPT’s help I was able to come up with a solution but I’m wondering if it’s an ideal solution or if there’s a better way of doing it. It would be really great if there was some helper function to get the collision force. I tried using get_contact_impulse but I was always getting back a Vector3 of (0, 0, 0) which might be because I have a mass of 5000 assigned to my RigidBody3D. Here’s the code I was able to put together that seems to work the way I want it to but I think it’s more complex then it needs to be.
static func compute_damage(state: PhysicsDirectBodyState3D) -> float:
# Check if the state object is valid
if state == null:
return 0.0
```
# Retrieve the contact count and iterate over each contact
var contact_count: int = state.get_contact_count()
var collision_force: Vector3 = Vector3.ZERO
var collision_torque: Vector3 = Vector3.ZERO
for i in range(contact_count):
# Retrieve the contact information for each contact
var contact_position: Vector3 = state.get_contact_local_position(i)
var contact_normal: Vector3 = state.get_contact_local_normal(i)
# Compute the collision velocity and mass of the other object
var other_body: PhysicsBody3D = state.get_contact_collider_object(i)
var other_velocity: Vector3 = other_body.get_linear_velocity()
var other_angular_velocity: Vector3 = other_body.get_angular_velocity()
var other_mass: float = other_body.get_mass()
var other_inertia_tensor: Vector3 = other_body.get_inverse_inertia_tensor().get_scale()
if other_inertia_tensor == Vector3.ZERO:
other_inertia_tensor = Vector3(1, 1, 1)
var relative_velocity: Vector3 = state.get_contact_collider_velocity_at_position(i) - other_velocity
var collision_speed: float = relative_velocity.dot(contact_normal)
# Compute the impulse using the collision speed and the masses of the colliding objects
var impulse: float = (1 + other_body.physics_material_override.bounce) * collision_speed
if other_mass > 0:
impulse /= state.get_inverse_mass() + 1.0 / other_mass
else:
impulse /= state.get_inverse_mass()
# Compute the collision force and torque for each contact
var contact_force: Vector3 = contact_normal * impulse
var contact_torque: Vector3 = contact_position.cross(contact_force)
# Accumulate the collision forces and torques from all contacts
collision_force += contact_force
# Compute the collision torque for each contact based on the contact position and contact force,
# using the other body's inverse inertia tensor to account for its rotational inertia
# and accumulate the torques from all contacts
collision_torque += other_inertia_tensor * (contact_position.cross(contact_force) + contact_torque)
# Calculate the magnitude of the total collision force and torque
var force_magnitude: float = collision_force.length()
var torque_magnitude: float = collision_torque.length()
# Use the collision force and torque to calculate damage and apply forces to the rigid body
var damage: float = force_magnitude / 1000.0 # Adjust this value as needed
return damage
```
ChatGPT’s knowledge of Godot 4 is quite limited/outdated but with feeding it enough information it was able help me come up with a solution.