tutorial-doublejump.md

Tutorial - Double Jump

We will now add the ability to allow up to X additional jumps while in air.

We will start by adding an int field in ThirdPersonCharacterComponent to determine how many air jumps we are allowed to do, and we will also add another int field to keep track of how many air jumps we've done so far.

[Serializable]
public struct ThirdPersonCharacterComponent : IComponentData
{
    // (...)

    public int MaxAirJumps;

    [UnityEngine.HideInInspector] // we don't want this field to appear in the inspector
    public int CurrentAirJumps;
}

The rest of the implementation will be done in ThirdPersonCharacterAspect.HandleVelocityControl. If we are not grounded and a jump is requested, we will check if we have reached our max in-air jumps count, and if not, we will jump. Also, when we are grounded, we always reset our CurrentAirJumps to 0.

public readonly partial struct ThirdPersonCharacterAspect : IAspect, IKinematicCharacterProcessor<ThirdPersonCharacterUpdateContext>
{
    // (...)

    private void HandleVelocityControl(ref ThirdPersonCharacterUpdateContext context, ref KinematicCharacterUpdateContext baseContext)
    {
        // (...)

        if (characterBody.IsGrounded)
        {
            // (...)

            // Reset air jumps when grounded
            characterComponent.CurrentAirJumps = 0;
        }
        else
        {
            // Move in air
            // (...)

            // Air Jumps
            if (characterControl.Jump && characterComponent.CurrentAirJumps < characterComponent.MaxAirJumps)
            {
                CharacterControlUtilities.StandardJump(ref characterBody, characterBody.GroundingUp * characterComponent.JumpSpeed, true, characterBody.GroundingUp);
                characterComponent.CurrentAirJumps++;
            }

            // Gravity
            // (...)
        }
    }
}

Now if you set MaxAirJumps to 1 in your character prefab and press Play, you should be able to double jump. Additional air jumps can be performed with a value of more than 1.