初步物理计算

palyer.gd

@@ -1,29 +1,56 @@
 extends CharacterBody3D
 
-var speed = 14
+## 角色的质量，单位 kg
+const weight := 60
+## 角色前进的动力,同样先简化处理，单位 N
+const power := 800
+## 一个最简单的阻尼系数[br]
+## 阻力计算公式 速度² × 阻尼系数[br]
+## 假设最高速度是慢跑 10km/h , 2.77m/s，那么阻力需要在这个速度下维持和动力平衡。也就是...104.3
+const damping := 104.3
+## 最后一次计算之后的，当前运动状态的向量
+var last_vector = Vector3.ZERO
 
 var fall_acceleration = 75
 
 var target_velocity = Vector3.ZERO
 
-func _physics_process(delta: float):
-	var direction = Vector3.ZERO
-	if Input.is_action_pressed("move_forward"):
-		direction.z -= 1
-	if Input.is_action_pressed("move_back"):
-		direction.z += 1
-	if Input.is_action_pressed("move_left"):
-		direction.x -= 1
-	if Input.is_action_pressed("move_right"):
-		direction.x += 1
-	if direction != Vector3.ZERO:
-		direction = direction.normalized()
-		$pivot.basis = Basis.looking_at(direction)
-	target_velocity.x = direction.x * speed
-	target_velocity.z = direction.z * speed
+func _physics_process(delta: float) -> void:
+	# 指令方向
+	var cmd_vector_direction := get_cmd_vector()
+	# 运动方向
+	var pre_vector_direction = last_vector.normalized()
+	# 计算当前运动状态，方向在上一步已经更新过了。剩下的是模量问题。
+	# 指令力
+	var cmd_vector_power = cmd_vector_direction * power
+	# 阻力
+	var damping_vector = -pre_vector.normalized() * last_vector.length_squared() * damping
+		
+	# 若指令方向和运动方向不同，则必然会产生
+	if cmd_vector_direction != pre_vector_direction:
+		pre_vector_direction = (pre_vector_direction + cmd_vector_direction).normalized()
+		$pivot.basis = Basis.looking_at(pre_vector_direction)
+	# 速度计算部分
+	#target_velocity.x = direction.x * now_speed
+	#target_velocity.z = direction.z * now_speed
 	
 	if !is_on_floor():
 		target_velocity.y = target_velocity.y - ( fall_acceleration * delta )
 	
 	velocity = target_velocity
 	move_and_slide()
+	
+## 获取当前指令的关联向量[br]
+## 难道需要两层才生效？
+func get_cmd_vector() -> Vector3:
+	var vector := Vector3.ZERO
+	if Input.is_action_pressed("move_forward"):
+		vector.z -= 1
+	if Input.is_action_pressed("move_back"):
+		vector.z += 1
+	if Input.is_action_pressed("move_left"):
+		vector.x -= 1
+	if Input.is_action_pressed("move_right"):
+		vector.x += 1
+	return vector.normalized()
+