Ios 计算将Box2D车身移动到特定位置的正确作用力-Box2D

我有一个关于将Box2D实体移动到特定位置而不使用此示例的问题

body->SetTransform(targetVector,body->GetAngle())

我有一些适用于applyForce（）的代码：

但是，当

maxSpeed

设置为高位时，身体会越过该点快速移动

那么，是否有人知道如何计算一个力（

ApplyForce

）或一个impluse（

ApplyLinearImpulse

）来在特定时间内将身体移动到目标位置（非常精确）

或者使用上述代码的解决方案。我的意思是计算

maxSpeed

，在特定时间内将身体移动到目标位置

在我的谷歌搜索中，我找到了来自iforce的一篇关于预测轨迹的有趣文章 (). 也许这也能帮上忙

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提前谢谢你

我想你说得基本正确，但你没有检查身体是否会在下一个时间步超过目标。以下是对我有效的方法：

b2Vec2 targetPosition = ...;
float targetSpeed = ...;

b2Vec2 direction = targetPosition - body->GetPosition();
float distanceToTravel = direction.Normalize();

// For most of the movement, the target speed is ok
float speedToUse = targetSpeed;

// Check if this speed will cause overshoot in the next time step.
// If so, we need to scale the speed down to just enough to reach
// the target point. (Assuming here a step length based on 60 fps)
float distancePerTimestep = speedToUse / 60.0f;
if ( distancePerTimestep > distanceToTravel )
    speedToUse *= ( distanceToTravel / distancePerTimestep );

// The rest is pretty much what you had already:
b2Vec2 desiredVelocity = speedToUse * direction;
b2Vec2 changeInVelocity = desiredVelocity - body->GetLinearVelocity();

b2Vec2 force = body->GetMass() * 60.0f * changeInVelocity;
body->ApplyForce( force, body->GetWorldCenter(), true );

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有一种方法可以使单次施加的力移动给定的距离（前面的答案表明，您可以在未来的帧中通过附加力来纠正计算中的错误）：

已知的限制：

1) LinearVelocity effect was not tested;
2) calculation was tested with body linear damping = 0.5f. Appreciate, if somebody know how to add it into formula;
3) magic number 30.45f - maybe this could be fixed by point 2 or by world frame delta.

public static void applyForceToMoveBy(float byX, float byY, Body body) {
    force.set(byX, byY);
    force.sub(body.getLinearVelocity());
    float mass = body.getMass();
    force.scl(mass * 30.45f);
    body.applyForceToCenter(force, true);
}

1) LinearVelocity effect was not tested;
2) calculation was tested with body linear damping = 0.5f. Appreciate, if somebody know how to add it into formula;
3) magic number 30.45f - maybe this could be fixed by point 2 or by world frame delta.