所以，我正在制作我自己的小行星游戏，而且我有点卡住了。当我按下Z键时，我有一颗从船上发射的子弹。但子弹总是向同一方向发射，我不知道如何改变它？我希望它能在船面朝下的方向发射。此外，如果我快速推动Z（发射许多子弹），一颗子弹似乎不断重置。我该如何解决这些问题？这是我的代码：
class SpaceShip
{
private Vector2 pos; //Our position in 2D.
private Texture2D tex; //Our texture
private float speed = 8; //The speed to move.
private float angleOfRotation = 0;
Sprite tempSprite;
public SpaceShip(Vector2 pos, Texture2D tex, Texture2D bulletsToAdd)
{
this.pos = pos; //Our starting position
this.tex = tex; //Our texture
tempSprite = new Sprite(bulletsToAdd);
}
private void WorldWrap(int worldWidth, int worldHeight)
{
if (this.pos.X < 0)
{
//If we've past the left side of the window, set on other side of the world.
this.pos.X = worldWidth;
}
if (this.pos.X > worldWidth)
{
//If we've past the right side of the window, set on other side of the world.
this.pos.X = this.tex.Width;
}
if (this.pos.Y < 0)
{
//If we've passed the top side of the window, set on other side of the world.
this.pos.Y = worldHeight;
}
if (this.pos.Y > worldHeight)
{
//If we've passed the bottom side of the window, set on other side of the world.
this.pos.Y = this.tex.Height;
}
}
public void CreateBullets(Texture2D bulletsToAdd)
{
tempSprite.Position = new Vector2((pos.X),(pos.Y));
tempSprite.Velocity = new Vector2((float)7, 7);
//tempSprite.Rotation = angleOfRotation;
}
public void Update(int WorldWidth, int WorldHeight, Texture2D bulletsToAdd)
{
KeyboardState keys = Keyboard.GetState();
if (keys.IsKeyDown(Keys.A))
{
//We want to turn the ship LEFT
this.angleOfRotation -= 2f;
}
if (keys.IsKeyDown(Keys.D))
{
//We want to turn the ship RIGHT
this.angleOfRotation += 2f;
}
if (keys.IsKeyDown(Keys.W))
{
//We're pressing the up key (W) so go Forwards!
this.pos.X += (float)(Math.Cos(this.angleOfRotation * Math.PI / 180) * this.speed);
this.pos.Y += (float)(Math.Sin(this.angleOfRotation * Math.PI / 180) * this.speed);
}
if (keys.IsKeyDown(Keys.S))
{
//We're pressing the down key (S) so go Backwards!
this.pos.X -= (float)(Math.Cos(this.angleOfRotation * Math.PI / 180) * this.speed);
this.pos.Y -= (float)(Math.Sin(this.angleOfRotation * Math.PI / 180) * this.speed);
}
if (keys.IsKeyDown(Keys.Right))
{
//We're pressing the up key (W) so go Forwards!
this.pos.X += (float)(Math.Cos(this.angleOfRotation * Math.PI / 180) * this.speed);
this.pos.Y += (float)(Math.Sin(this.angleOfRotation * Math.PI / 180) * this.speed);
}
if (keys.IsKeyDown(Keys.Left))
{
//We're pressing the down key (S) so go Backwards!
this.pos.X -= (float)(Math.Cos(this.angleOfRotation * Math.PI / 180) * this.speed);
this.pos.Y -= (float)(Math.Sin(this.angleOfRotation * Math.PI / 180) * this.speed);
}
if (keys.IsKeyDown(Keys.Up))
{
//We want to turn the ship LEFT. Rotate it counter-clockwise
this.angleOfRotation -= 2f;
}
if (keys.IsKeyDown(Keys.Down))
{
//We want to turn the ship RIGHT. Rotate it clockwise
this.angleOfRotation += 2f;
}
if (keys.IsKeyDown(Keys.Z))
{
CreateBullets(bulletsToAdd);
}
tempSprite.Position += tempSprite.Velocity;
//check if we need to move the ship.
WorldWrap(WorldWidth, WorldHeight);
}
public void Draw(SpriteBatch batch)
{
batch.Draw(this.tex, //Texture to use.
this.pos, //Position to draw at
new Rectangle(0, 0, this.tex.Width, this.tex.Height),Color.White, (float)((this.angleOfRotation + 90) * Math.PI / 180), new Vector2(this.tex.Width / 2, this.tex.Height / 2), 1.0f, SpriteEffects.None, 0.0f);
batch.Draw(tempSprite.Texture, tempSprite.Position, null, Color.White, tempSprite.Rotation, tempSprite.Center, tempSprite.Scale, SpriteEffects.None, 1.0f);
} //End Draw function
答案 0 :(得分：3)
首先，你只有一枚子弹 - tempSprite。你可能想要在某个地方创建一个单独的Bullet类和List<Bullet>，你可以在其中添加项目符号。
你需要的只是一点三角学。现在你的速度矢量是常数＆lt; 7,7＆gt;。你想要做的是让那个向量朝向宇宙飞船指向的方向。因此，假设您的角度是弧度而不是度数（如果它们以度为单位，您需要将它们更改为弧度），我们可以使用Math.Sin()和Math.Cos()来获取单个X和Y分量像这样的速度矢量：
bulletSpeed = 7;
tempSprite.Velocity = new Vector2((float)Math.Cos(angleOfRotation) * bulletSpeed, (float)Math.Sin(angleOfRotation) * bulletSpeed);