你的程序逻辑应如下所示：

注意：这仅是简化版本，而不是工作示例。它应该给你提示如何做。

int main() 
{
    openWindow();
    while (active) {
        getTime();
        processMessages();
        doLogic();
        renderScene();
        swapBuffers();
    }
    closeWindow();
}

void getTime()
{
    // you have to know the time unit (sec, ms, us, ns, etc.)
    current_time = systemTime(); 
}

void processMessages()
{
    while (nextEvent()) {
        if (EventType == EvtClosed) {
            active = false;
        }
        if ((EventType == KeyPressed) && (KeyType == KeySpace) && !jumping) {
            jump_start = current_time;
            jumping = true;
        }
    }
}

void doLogic()
{
    if (jumping) {
        // time_frac has to be in range [0.0..1.0]
        time_frac = (current_time - jump_start) / time_units_per_second;
        // linear interpolation based on time fraction
        pos = start_pos * (1 - time_frac) + end_pos * time_frac;
    }
}

void renderScene()
{
    printf("%f\n", pos);
}