刚一个朋友问跳跃怎么实现,其实对xna我也不了解,Zzk里搜索“XNA 跳跃”居然没有符合的记录,惊讶之余也有点冲动要不自己也搞一个?不过xna真的是不懂啊,找了两三个源码,笔者实在笨,没能理解它的算法实在见笑了。干脆自己动手从头实现一个,先从现实考虑起跳要考虑的因素是起跳速度(v1)体重(w)重力g然后根据物理xxx记不得了,咱不好高骛远了,simple is perfect 直接上代码:
全局参数:
private bool _isJumping;
private bool _jumpKeyDown;
private float _jumpHeight = 100f;
private TimeSpan _jumpTimeSpan = TimeSpan.FromMilliseconds(500);
private double _jumpStartTime;
private float _jumpStartPosition;
Update中的代码:
_jumpKeyDown = Keyboard.GetState().IsKeyDown(Keys.Space);
squarePosition.Y = DoJump(squarePosition.Y, gameTime);
高度算法函数:
private float DoJump(float velocityY, GameTime gameTime)
{
if (_jumpKeyDown && !_isJumping)
{
_isJumping = true;
_jumpStartTime = gameTime.TotalGameTime.TotalMilliseconds;
_jumpStartPosition = velocityY;
}
if (_isJumping)
{
var jumpTime = gameTime.TotalGameTime.TotalMilliseconds - _jumpStartTime;
var topTime = _jumpTimeSpan.TotalMilliseconds / 2;
if (jumpTime < _jumpTimeSpan.TotalMilliseconds)
{
if (jumpTime > topTime)
{
velocityY =
_jumpStartPosition-_jumpHeight - Convert(-(jumpTime - topTime) * _jumpHeight / (_jumpTimeSpan.TotalMilliseconds - topTime));
}
else
{
velocityY =_jumpStartPosition+ Convert(-( jumpTime)*_jumpHeight/topTime);
}
}
else
{
_isJumping = false;
velocityY = _jumpStartPosition;
}
}
return velocityY;
}