2

现在。我将其设置为从我的角色方向发射子弹。但我希望能够将子弹射向鼠标点，让玩家更轻松。

现在是

if(gun_1[i].direction == 2){ gun_1[i].x -= gun_1[i].speed * modifier};
if(gun_1[i].direction == 3){ gun_1[i].x += gun_1[i].speed * modifier};
if(gun_1[i].direction == 1){ gun_1[i].y -= gun_1[i].speed * modifier};
if(gun_1[i].direction == 4){ gun_1[i].y += gun_1[i].speed * modifier };
if(gun_1[i].direction == 5){ gun_1[i].y -= gun_1[i].speed * modifier; gun_1[i].x -= gun_1[i].speed * modifier };
if(gun_1[i].direction == 7){ gun_1[i].y += gun_1[i].speed * modifier; gun_1[i].x -= gun_1[i].speed * modifier };
if(gun_1[i].direction == 6){ gun_1[i].y -= gun_1[i].speed * modifier; gun_1[i].x += gun_1[i].speed * modifier };
if(gun_1[i].direction == 8){ gun_1[i].y += gun_1[i].speed * modifier; gun_1[i].x += gun_1[i].speed * modifier };

我希望能够拍摄到鼠标点击的位置。如果可能的话。

4

3 回答 3

5

当然，这并不太难。但是您也可以做很多事情来改进您当前的设计。首先，添加velocityX和velocityY字段，以便在每个步骤中您只需要更新项目符号的位置：

gun_1[i].x += gun_1[i].velocityX
gun_1[i].y += gun_1[i].velocityY

然后当鼠标按下时，设置子弹的速度：

canvas.onmousedown = function(e) {
   var dx = (e.x - character.x);
   var dy = (e.y - character.y);
   var mag = Math.sqrt(dx * dx + dy * dy);

   // whatever you need to do to get gun_1[i]

   gun_1[i].velocityX = (dx / mag) * speed;
   gun_1[i].velocityY = (dy / mag) * speed;
}

如果您对向量有所了解，我们只是将方向向量归一化并与标量初始速度相乘。

于 2013-05-26T05:55:00.710 回答
2

另一个答案：

gun_1[i].x += gun_1[i].velocityX;
gun_1[i].y += gun_1[i].velocityY;


var dx = (e.x - character.x);
var dy = (e.y - character.y);
var angle = Math.atan2(dy, dx);

gun_1[i].velocityX = Math.cos(angle) * speed;
gun_1[i].velocityY = Math.sin(angle) * speed;
于 2014-03-04T18:53:15.407 回答
0 
   var i=0;
        var maxBullets=10;
        var allBullets=[];//a array for objects

        function bullet(){
           this.vx=0;
           this.vy=0;
           this.inix=0;
           this.iniy=0;
           this.angleGrads=0;
           this.angleRads=1.0;
           this.active=false;
        }
        bullet.prototype.exist=function(){
         //this.inix+=mathsin.bla,bla.bla.bla  bla
         if(this.x > wordWidth){
           //kill this bullet
           this.active=false;
          }
        }
        bullet.prototype.draw=function(){
          //ctx.draw bla, bla, bla 
        }
        function newBullets(){
          for(i=1;i<=maxBullets;i++){
            allBullets[i]=new bullet();
          }
        }
    function launchBullets(){
         for(i=1;i<=maxBullets;i++){
            if(!allBullets[i].active){
              //detemine angle with a point an the mouse point
              // math atan2()  ;)
              //asing values to this bullet
             allBullets[i].angleGrads=angleMouse;
             allBullets[i].inix=mousex;
             allBullets[i].iniy=mousey;
             allBullets[i].angleRads=(allBullets[i].angleGrads*PI)/180;
             //and end
             allBullets[i].active=true;
             //get out
             break;
            }
          }
    }//end of launchBullets

    function operations(){
      for(i=1;i<=maxBullets;i++){
            if(allBullets[i].active){
              allBullets[i].exist();
        }
      }
    }
    function paint(){
    for(i=1;i<=maxBullets;i++){
            if(allBullets[i].active){
              allBullets[i].draw();
        }
      }
    }//end of draw scene
于 2015-04-22T00:04:01.947 回答