How to detect player movement speed on rotating platforms?

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#1

  1. What do you want to achieve?
    I want to adjust my animations accordingly to the players movement speed.

  2. What is the issue?
    The simple check of the RootPart’s Velocity Magnitude provides wrong results when on rotating platforms. While the issue is miniscule, I still love to add those little details to my games.

  3. What solutions have you tried so far?
    At first I thought it was simple, just subtract the velocity of the platform, but it only works if the platform isn’t rotating!

function update_speed() : nil
	local base_speed = animation_variables.BaseSpeeds[current_anim]
	if base_speed then
		local character_vel = root_part.AssemblyLinearVelocity
		local ground_vel = Vector3.zero
		
		if controller.ActiveController:IsA("ClimbController") then
			ground_vel = climb_sensor.SensedPart.AssemblyLinearVelocity
		elseif controller.ActiveController:IsA("GroundController") then
			ground_vel = ground_sensor.SensedPart.AssemblyLinearVelocity
		end
		
		set_animation_speed((character_vel - ground_vel).Magnitude/base_speed*movement_direction)
	end
end

A few extra notes I’d like to mention is that I do use the new Physics - Based Character Controller.

#2

Found the solution! I can’t explain it at all but it works, lol.

local function update_speed()
    local base_speed = animation_variables.BaseSpeeds[current_anim]
    if base_speed then
        local character_vel = root_part.AssemblyLinearVelocity
        local ground_vel = Vector3.zero

        if controller.ActiveController:IsA("ClimbController") then
            if climb_sensor.SensedPart then
                ground_vel = climb_sensor.SensedPart.AssemblyLinearVelocity
                local angular_vel = climb_sensor.SensedPart.AssemblyAngularVelocity
                local relative_pos = root_part.Position - climb_sensor.SensedPart.Position
                local rotational_vel = angular_vel:Cross(relative_pos)
                ground_vel = ground_vel + rotational_vel
            end
        elseif controller.ActiveController:IsA("GroundController") then
            if ground_sensor.SensedPart then
                ground_vel = ground_sensor.SensedPart.AssemblyLinearVelocity
                local angular_vel = ground_sensor.SensedPart.AssemblyAngularVelocity
                local relative_pos = root_part.Position - ground_sensor.SensedPart.Position
                local rotational_vel = angular_vel:Cross(relative_pos)
                ground_vel = ground_vel + rotational_vel
            end
        end

        set_animation_speed((character_vel - ground_vel).Magnitude / base_speed * movement_direction)
    end
end