Topdown游戏中Input朝向的转化

前提

在Topdown双摇杆游戏中，我们需要将摇杆输入朝向转到摄像机空间，以实现往前走是往屏幕的前方，往后是往屏幕的后方，而不是原始的输入朝向。

我们只讨论固定视角并且player只有y轴旋转的游戏。

实现

需要进行一个Vector2的映射

private static Vector3 ViewSpaceToGroundSpace(float cameraAngleY, Vector2 vec)
{
    float angleRad = -cameraAngleY * Mathf.Deg2Rad;
    float cos = Mathf.Cos(angleRad);
    float sin = Mathf.Sin(angleRad);

    Vector2 rotated = new Vector2(
        vec.x * cos - vec.y * sin,
        vec.x * sin + vec.y * cos
    );

    return new Vector3(rotated.x, 0f, rotated.y);
}

 

旋转和瞄准

双摇杆下我们需要区分旋转和瞄准的实现。

其中旋转的实现，鼠标和摇杆是一致的

 

      private static Vector3 GetMovementInputGroundSpace(Transform camera, int horizontalActionId, int verticalActionId, float deadZone)
        {
            var input = InputExtension.GetAxis2D(horizontalActionId, verticalActionId);
            if (input.sqrMagnitude > 1) input = input.normalized;
            input = InputExtension.InputWithRadialDeadZone(input.x, input.y, deadZone);
            return ViewUtils.ViewSpaceToGroundSpace(camera, input).normalized;
        }

 

瞄准朝向的获取，鼠标相对复杂一点，需要在开火的水平面做映射

 

 

        private static Vector3 GetAimInputInGroundSpace(GameEntity gameEntity, Camera camera, int horizontalActionId, int verticalActionId)
        {
            if (InputExtension.IsKeyboarding())
            {
                if (InputExtension.GetButton(InputAction.Aim))
                { 9                     var playerFirePoint = gameEntity.GetObject<WeaponFirePointTag>().Component;
                    Transform playerTransform = gameEntity.Get<Transform>();
                    Vector3 refPosition = playerTransform.position;
                    refPosition.y = playerFirePoint.position.y;
                    var ray = camera.ScreenPointToRay(InputExtension.MousePosition);
                    //we need a plane to project the aim direction to the aiming ground : https://forum.unity.com/threads/3rd-person-look-at-mouse-script.1078358/
                    var aimingPlane = new Plane(Vector3.up, refPosition);
                    aimingPlane.Raycast(ray, out float distance);
                    var aimDestDirection = (ray.origin + distance * ray.direction - refPosition).normalized;
                    var rotation = Quaternion.LookRotation(aimDestDirection);
                    return rotation * Vector3.forward;
                }

                return Vector3.zero;
            }

            var input = InputExtension.GetAxis2D(horizontalActionId, verticalActionId);
            return ViewUtils.ViewSpaceToGroundSpace(camera, input).normalized;
        }