vibe code differential movment

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defold_game/main/player.script

@@ -1,54 +1,54 @@
-go.property("speed", 100)
-go.property("rotation_speed", 3)
+go.property("acceleration", 100)
+go.property("deceleration", 200)
+go.property("max_speed", 400)
+go.property("wheel_base", 40)  -- pixels between left and right wheels
+
+local UP = vmath.vector3(0, 1, 0)
 
 function init(self)
-	msg.post(".", "acquire_input_focus")
-	self.rotation = 0
-	self.rotating_left = false
-	self.rotating_right = false
-	self.moving_forward = false
+    msg.post(".", "acquire_input_focus")
+
+    self.left_speed = 0
+    self.right_speed = 0
+    self.left_input = false
+    self.right_input = false
 end
 
 function update(self, dt)
-	if self.rotating_left then
-		self.rotation = self.rotation + self.rotation_speed * dt
-	end
-	if self.rotating_right then
-		self.rotation = self.rotation - self.rotation_speed * dt
-	end
-	print("Rotation" .. self.rotation)
-	if self.moving_forward then
-		local vx = math.cos(self.rotation) * self.speed
-		local vy = math.sin(self.rotation) * self.speed
+    -- each wheel accelerates when its key is held, decelerates otherwise
+    if self.left_input then
+        self.left_speed = math.min(self.left_speed + self.acceleration * dt, self.max_speed)
+    else
+        self.left_speed = math.max(self.left_speed - self.deceleration * dt, 0)
+    end
 
-		local pos = go.get_position()
-		pos.x = pos.x + vx * dt
-		pos.y = pos.y + vy * dt
-		go.set_position(pos)
-	end
+    if self.right_input then
+        self.right_speed = math.min(self.right_speed + self.acceleration * dt, self.max_speed)
+    else
+        self.right_speed = math.max(self.right_speed - self.deceleration * dt, 0)
+    end
 
+    -- differential drive: speed difference creates rotation, average creates forward motion
+    local linear_speed = (self.left_speed + self.right_speed) / 2
+    local angular_vel = (self.right_speed - self.left_speed) / self.wheel_base
 
+    local rot = go.get_rotation()
+    rot = rot * vmath.quat_rotation_z(angular_vel * dt)
+    go.set_rotation(rot)
+
+    local p = go.get_position()
+    p = p + vmath.rotate(rot, UP * linear_speed * dt)
+    go.set_position(p)
+
+    -- reset each frame (on_input re-sets if key is still held)
+    self.left_input = false
+    self.right_input = false
 end
 
-
 function on_input(self, action_id, action)
-	-- Rotate with A/D keys
-	if action_id == hash("left_wheel_fwd") and action.pressed then
-		self.rotating_left = true
-	elseif action_id == hash("left_wheel_fwd") and action.released then
-		self.rotating_left = false
-	end
-
-	if action_id == hash("right_wheel_fwd") and action.pressed then
-		self.rotating_right = true
-	elseif action_id == hash("right_wheel_fwd") and action.released then
-		self.rotating_right = false
-	end
-
-	-- Move forward with W
-	if (action_id == hash("left_wheel_fwd") or action_id == hash("right_wheel_fwd")) and action.pressed then
-		self.moving_forward = true
-	elseif (action_id == hash("left_wheel_fwd") or action_id == hash("right_wheel_fwd")) and action.released then
-		self.moving_forward = false
-	end
+    if action_id == hash("a_key") then
+        self.left_input = true
+    elseif action_id == hash("d_key") then
+        self.right_input = true
+    end
 end