我有一个多人 Javascript 游戏,其中玩家是一个圆圈,并且能够沿着玩家旋转的方向射击/“弹出”圆圈子弹。我的代码工作完美,除了它从播放器的中间射击。我希望圆圈是从玩家的右上角位置(枪所在的位置)射击的。问题是,当球员轮换发生变化时,您不能简单地将 (1, -1) 添加到球员的位置。
这是我的代码:
GameServer.prototype.ejectMass = function(client) {
for (var i = 0; i < client.cells.length; i++) {
var cell = client.cells[i]; // the player
var angle = this.toRad(client.rotation); // rotation of the player
var d = new Vec2(Math.sin(angle), Math.cos(-angle)).scale(-180);
var sq = (~~d.sqDist(d));
d.x = sq > 1 ? d.x / sq : 1;
d.y = sq > 1 ? d.y / sq : 0;
// cell.position is the players position
var pos = new Vec2(
cell.position.x + d.x * cell._size,
cell.position.y + d.y * cell._size
);
var ejected = 0;
// Create cell and add it to node list
ejected = new Entity.EjectedMass(this, null, pos, this.config.ejectSize * cell.ejectSize); // the bullet being shot
ejected.setBoostDefault(-this.config.ejectVelocity * cell.ejectSpeed, angle);
ejected.ejectedOwner = cell; // set the person who shot the bullet
this.addNode(ejected); // add the bullet into the game
if (typeof ejected !== 'undefined') {
setTimeout(this.removeNode.bind(this, ejected), 1000); // remove the ejected bullet after 1 second
}
}
};
最佳答案
假设玩家(圆圈)位于其自己的本地原点,那么枪的位置是相对于玩家的原点的。假设坐标系为 Canvas 坐标系,从左向右沿x轴向前,顺时针90度(玩家左侧)为Y轴向下。
图片:C 是本地圆原点 (0,0),从 C 沿红色箭头向前,< strong>Gx和Gy是枪距圆心C的局部坐标。左上角显示 Canvas 坐标(世界)系统原点。在下面的代码中,玩家
位置是相对于世界原点的。最终的gunPos也是相对于世界坐标给出的。 B vec 是子弹 bullet.delta
向量
const bulletSpeed = 10;
var gunPos = {x : 10, Y : 10} // ten units forward ten units left of circle center
var player = {rotation : ?, x : ?, y : ?} // unknown player position and rotation
// get the unit vector of the rotated x axis. Along player forward
var xAx = Math.cos(player.rotation);
var xAy = Math.sin(player.rotation);
// transform the gunpos to absolute position (world coordinates) of rotated player
var rotatedGunPos = {};
rotatedGunPos.x = gunPos.x * xAx - gunPos.y * xAy + player.x;
rotatedGunPos.y = gunPos.x * xAy + gunPos.y * xAx + player.y;
// and fire the bullet from
var bullet = {}
bullet.x = rotatedGunPos.x;
bullet.y = rotatedGunPos.y;
// bullet vector is
bullet.deltaX = xAx * BULLET_SPEED;
bullet.deltaY = xAy * BULLET_SPEED;
关于javascript - 根据旋转 Angular 计算新的圆偏移?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/44353557/