在 Unity 2D 中使用物理冲撞斜坡

Question

我正在使用 Unity 开发一个 2D 项目。

角色控制器是基于物理的，所以我使用刚体来移动玩家。一切正常，除非我尝试对角色应用高速运动，如破折号。

这就是代码的样子。

我只是检查玩家是否在冲刺，所以我将Vector2的运动量增加了一定量。

    private void DashMovement() {
        if (isDashing) {
            movement.x *= dashFactor;
        }
    }

我也在计算地面角度，所以我将运动矢量设置为跟随地面倾斜度。

     private void OnSlopeMovement() {
        if (isGrounded && !isJumping) {
            float moveDistance = Mathf.Abs(movement.x);
            float horizontalOnSlope = Mathf.Cos(groundAngle * Mathf.Deg2Rad) * moveDistance * Mathf.Sign(movement.x);
            float verticalOnSlope = Mathf.Sin(groundAngle * Mathf.Deg2Rad) * moveDistance;

            if (horizontalOnSlope != 0)
                movement.x = horizontalOnSlope;
            if (isGrounded && verticalOnSlope != 0)
                movement.y = verticalOnSlope;
        }

        SetMaxFallVelocity();
    }

所以我设置了刚体速度以使其移动。

    private void Move() {
        movement.x *= Time.fixedDeltaTime;
        if(isGrounded && !isJumping) movement.y *= Time.fixedDeltaTime;
        Vector3 targetVelocity = new Vector2(movement.x, movement.y);

        PlayerController.rb2d.velocity = Vector3.SmoothDamp(PlayerController.rb2d.velocity, targetVelocity, ref velocity, movementSmoothing);
    }

当我应用足够高的速度时会出现问题。我知道这个问题是因为物理学。 我认为检查地面并用于计算 groundAngle 的光线工作速度不够快，无法跟踪该运动，因此我无法将玩家固定在地面上。

我想在不使玩家运动或在斜坡上停止冲刺的情况下找到解决方案。

This is how it looks ingame.

And this is how the rigidbody movement remain right over the ground, following the slopes angle.

编辑：

这就是我获得地面角度的方式：

private void GroundAngle() {
        Vector2 rayOrigin = feetCollider.bounds.center;
        rayOrigin.y += 0.1f;
        Vector2 rayDirection = (Input.GetAxisRaw("Horizontal") == 0) ? Vector2.right : new Vector2(Input.GetAxisRaw("Horizontal"), 0);

        int groundCollisions = Physics2D.RaycastNonAlloc(rayOrigin, Vector2.down, groundResults, Mathf.Infinity, groundMask);
        if (groundCollisions > 0) {
            groundAngle = Vector2.Angle(groundResults[0].normal, rayDirection) - 90f;
            //Debug.DrawRay(rayOrigin, Vector2.down, Color.green);
            if (groundAngle > 0 && !isDashing) {
                rayOrigin.x += Input.GetAxisRaw("Horizontal") * .125f;
                Physics2D.RaycastNonAlloc(rayOrigin, Vector2.down, groundResults, Mathf.Infinity, groundMask);
                groundAngle = Vector2.Angle(groundResults[0].normal, rayDirection) - 90f;
                //Debug.DrawRay(rayOrigin, Vector2.down, Color.blue);
            }
        } 
    }

感谢@Ruzhim 的帮助。我只是为这个问题发布了第一个“解决方案”。 根据 Ruzhim 的建议，我是这样使用他的代码的。

private void SetPositionAfterTick() {
        if (isDashMovement) {
            Vector2 currentPosition = new Vector2(transform.position.x, transform.position.y);
            currentPosition.y = feetCollider.bounds.min.y;
            Vector2 feetPosAfterTick = currentPosition + PlayerController.rb2d.velocity * Time.deltaTime;

            float maxFloorCheckDist = .1f;

            RaycastHit2D groundCheckAfterTick = Physics2D.Raycast(feetPosAfterTick + Vector2.up * maxFloorCheckDist, Vector2.down, maxFloorCheckDist * 5f);

            if (groundCheckAfterTick) {
                Vector2 wantedFeetPosAfterTick = groundCheckAfterTick.point;

                if (wantedFeetPosAfterTick != feetPosAfterTick) {
                    //PlayerController.rb2d.transform.position = (wantedFeetPosAfterTick + new Vector2(0f, feetCollider.bounds.min.y - PlayerController.rb2d.position.y));
                    PlayerController.rb2d.velocity = Vector2.zero;
                }
            }
        }
    }

This is how it looks like.

这足以继续完善该机制。我仍然需要以某种方式设置位置。刚体的位置计算不起作用 现在被提升，因为条件 (wantedFeetPosAfterTick != feetPosAfterTick) 始终为真，所以角色会摔倒地板并摔倒。

如你所见，我还需要控制下坡运动，因为它有时会使用斜坡运动，而其他人则向前冲刺。

Answer 1

这就是asker Rubzero 实现以下代码为他们工作的方式：

private void SetPositionAfterTick() {
    if (isDashMovement) {
        Vector2 currentPosition = new Vector2(transform.position.x, transform.position.y);
        currentPosition.y = feetCollider.bounds.min.y;
        Vector2 feetPosAfterTick = currentPosition + PlayerController.rb2d.velocity * Time.deltaTime;

        float maxFloorCheckDist = .1f;

        RaycastHit2D groundCheckAfterTick = Physics2D.Raycast(feetPosAfterTick + Vector2.up * maxFloorCheckDist,
                Vector2.down, maxFloorCheckDist * 5f);

        if (groundCheckAfterTick) {
            Vector2 wantedFeetPosAfterTick = groundCheckAfterTick.point;

            if (wantedFeetPosAfterTick != feetPosAfterTick) {
                //PlayerController.rb2d.transform.position = (wantedFeetPosAfterTick + new Vector2(0f, feetCollider.bounds.min.y -
                        PlayerController.rb2d.position.y));
                PlayerController.rb2d.velocity = Vector2.zero;
            }
        }
    }
} 

This is how it looks like.

这足以继续完善该机制。我还需要 以某种方式设置位置。刚体的位置计算 不工作，因为它现在提出，作为条件 (wantedFeetPosAfterTick != feetPosAfterTick) 总是正确的，所以 角色摔倒在地。

如您所见，我需要控制下坡运动，因为它使用 时而斜坡运动，时而向前冲刺。

---

我同意 AresCaelum 的观点；如果您不想在完成上坡/下坡时保持动量，则使用物理学进行坡度运动与您想要做的事情几乎相反。具体来说，您的问题就在这里：

float moveDistance = Mathf.Abs(movement.x);
float horizontalOnSlope = Mathf.Cos(groundAngle * Mathf.Deg2Rad) * moveDistance * Mathf.Sign(movement.x);
float verticalOnSlope = Mathf.Sin(groundAngle * Mathf.Deg2Rad) * moveDistance;

这是一个问题，因为玩家在一帧中水平移动的次数越多，根据他们所在坡道的斜率，他们垂直移动的次数就越多。然而，如果他们应该只在帧期间的部分移动期间沿着坡道行进，则此假设不成立。因此，您需要一种方法来处理这种情况。

一种解决方案是使用来自玩家所在位置的光线投射，然后如果玩家在地板上方，则更改垂直速度，以便将玩家放置在该地板的位置。

首先，确定物理框架中是否发生了斜坡运动...

 private bool slopeMovementOccurred = false;

 void FixedUpdate() {
     slopeMovementOccurred = false;

     // ...
 }

 private void OnSlopeMovement() {
    if (isGrounded && !isJumping) {
        slopeMovementOccurred = true; 

        // ...
    }

    SetMaxFallVelocity();
}

...如果有，请确定玩家在物理更新后的位置。然后从该位置上方（一定量）向下（前一个量的两倍）进行物理 2d 射线投射以找到玩家的位置应该在哪里，然后更改 rb2d.velocity 以便它将玩家准确地放置在他们应该的高度在。

假设你可以计算出某种具有玩家脚部位置的Vector2 feetOffset：

void FixedUpdate() {
    // ...

    StickToSlopeLanding();
}

void StickToSlopeLanding() {
    if (slopeMovementOccurred) {
        Vector2 curVelocity = PlayerController.rb2d.velocity;
        Vector2 feetPosAfterTick = PlayerController.transform.position 
                + PlayerController.feetOffset 
                + curVelocity * Time.deltaTime;

        float maxFloorCheckDist = 1.0f;

        // determine where the player should "land" after this frame
        RaycastHit2D groundCheckAfterTick = Physics2D.Raycast(
                feetPosAfterTick + Vector2.up * maxFloorCheckDist, 
                -Vector2.up, maxFloorCheckDist * 2f);

        if (groundCheckAfterTick.collider != null) {
            Vector2 wantedFeetPosAfterTick = groundCheckAfterTick.point;

            // if basic physics won't take them to landing position
            if (wantedFeetPosAfterTick != feetPosAfterTick) {
                Vector2 wantedVelocity = curVelocity 
                        + Vector2.up 
                        * ((wantedFeetPosAfterTick.y - feetPosAfterTick.y)
                            / Time.deltaTime);

                // adjust velocity so that physics will take them to landing position
                PlayerController.rb2d.velocity = wantedVelocity;

                // optionally, set a flag so that next frame 
                // it knows the player should be grounded
            }
        }
    }
} 

希望这能让您找到可行的解决方案。

---

注意：您可能还需要移动刚体，使其不会尝试穿过坡道顶部的拐角，并且您可以使用另一个光线投射来确定将刚体放置在哪里，并从中设置速度指向水平：

void StickToSlopeLanding() {
    if (slopeMovementOccurred) {
        Vector2 curVelocity = PlayerController.rb2d.velocity;
        Vector2 feetPosAfterTick = PlayerController.transform.position 
                + PlayerController.feetOffset 
                + curVelocity * Time.deltaTime;

        float maxFloorCheckDist = 1.0f;

        // determine where the player should "land" after this frame
        RaycastHit2D groundCheckAfterTick = Physics2D.Raycast(
                feetPosAfterTick + Vector2.up * maxFloorCheckDist, 
                -Vector2.up, maxFloorCheckDist * 2f);

        if (groundCheckAfterTick.collider != null) {
            Vector2 wantedFeetPosAfterTick = groundCheckAfterTick.point;

            // if basic physics won't take them to landing position
            if (wantedFeetPosAfterTick != feetPosAfterTick) {

                // look for corner of ramp+landing. 
                // Offsets ensure we don't raycast from inside/above it
                float floorCheckOffsetHeight = 0.01f;
                float floorCheckOffsetWidth = 0.5f;
                RaycastHit2D rampCornerCheck = Physics2D.Raycast(
                        wantedFeetPosAfterTick 
                        - floorCheckOffsetHeight * Vector2.up 
                        - floorCheckOffsetWidth * Mathf.Sign(movement.x) * Vector2.right,
                        Mathf.Sign(movement.x) * Vector2.right);

                if (rampCornerCheck.collider != null) {
                    // put feet at x=corner position
                    Vector2 cornerPos = Vector2(rampCornerCheck.point.x, 
                            wantedFeetPosAfterTick.y);

                    PlayerController.rb2d.position = cornerPos 
                            - PlayerController.feetOffset;
                    // adjust velocity so that physics will take them from corner 
                    // to landing position
                    Vector2 wantedVelocity = (wantedFeetPosAfterTick - cornerPos) 
                            / Time.deltaTime;

                    PlayerController.rb2d.velocity = wantedVelocity;

                    // optionally, set a flag so that next frame 
                    // it knows the player should be grounded
                }
            }
        }
    }
}