速度增加

Question

当我将对象移动到其开始位置时非常慢，然后开始加速。我希望有一个恒定的速度，但我不知道什么是错的

const float m_Walkspeed = 0.1; 

    if (sf::Keyboard::isKeyPressed(sf::Keyboard::Left) && m_position.x > 0) 
    { 
     m_velocity.x -= m_Walkspeed; 
     CurrentAnimation = &AnimationLeft; 
    } 

    if (sf::Keyboard::isKeyPressed(sf::Keyboard::Right) && m_position.x < 800) 
    { 
     m_velocity.x += m_Walkspeed; 
     CurrentAnimation = &AnimationRight; 
    } 

    if (sf::Keyboard::isKeyPressed(sf::Keyboard::Up) && m_position.y > 0) 
    { 
     m_velocity.y -= m_Walkspeed; 
     CurrentAnimation = &AnimationUp; 
    } 

    if (sf::Keyboard::isKeyPressed(sf::Keyboard::Down) && m_position.y < 560) 
    { 
     m_velocity.y += m_Walkspeed; 
     CurrentAnimation = &AnimationDown; 
    } 

    m_position += m_velocity; 
    m_velocity = sf::Vector2f(0, 0); 
    CurrentAnimation->setPosition(m_position); 
} 

Answer 1

假设你在每一帧调用这个代码，你必须要考虑的时间，因为最后一帧：

m_velocity += timeSinceLastFrame; 
m_position += m_velocity;