在Y秒内加速到X速度

Question

How can I get something to go from X to Xgoal velocity in Y seconds? The goalVelocity is set to (100, 100) and it does approach it but it takes way too long to get there.

I can multiply frameDelta by some number like 20 or 100 but I want to find out what to multiply frameDelta by to get it to reach goalVelocity in some number of seconds.

velocity, goalVelocity and origin are all Vec2f and frameDelta is a float

Right now I have this code:

velocity = approach(goalVelocity, velocity, frameDelta);
origin = origin + velocity * frameDelta;

The code for approach is:

inline float approach(float flGoal, float flCurrent, float dt)
{
    float flDifference = flGoal - flCurrent;

    if (flDifference > dt)
        return flCurrent + dt;
    if (flDifference < -dt)
        return flCurrent - dt;

    return flGoal;
}

inline Vec2f approach(Vec2f flGoal, Vec2f flCurrent, float dt)
{
    return Vec2f(approach(flGoal.x, flCurrent.x, dt), approach(flGoal.y, flCurrent.y, dt));
}

Answer 1

也许我误解了您的问题，但是加速度只是速度差除以时间，因此只需将dt与X / Y相乘即可。

Answer 2

A basic physics engine should look something like

   Vec2f position, velocity, acceleration;

   while (true)
   {
     acceleration = button ? thrust : 0;
     velocity += acceleration * timeDelta;
     position += velocity * timeDelta
     redraw space ship at position;
     sleep (timeDelta);
   }

if you want to go from 0 to X velocity in Y seconds, then thrust = X/Y .