爲什麼忽略這兩個位置？

Question

我寫一些JavaScript從陣列創建X和Y座標，所以我有這樣的代碼：

var map1 = [ 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
    gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg,gg, 
]; 
    for (var i=0; i<map1.length; i++) { 
    if (i > 16) { 
     dy = Math.floor(i/15) * 16; 
    } 
    dx = i * 16 
    while (dx >= 240) { 
     dx = dx - 240; 
    } 
    } 

和代碼作品非常好，除了座標0,1和1,1的arent工作？這些座標正在使用此頁面上的主體here構建一個具有16px塊的畫布。並dx和dy適合這個等式，ctx.drawImage(tileset, sx, sy, sWidth, sHeight, dx, dy, dWidth, dHeight);謝謝！

Answer 1

不知道這是否有幫助 - 但控制檯中的以下代碼片段似乎爲所有位置提供了正確的結果。你能解釋一下你期望的輸出與你得到的實際輸出嗎？

var map1 = new Array(225); 
var dx, dy; 

for (var i=0; i<map1.length; i++) { 
    if (i > 16) { 
     dy = Math.floor(i/15) * 16; 
    } 
    dx = i * 16 
    while (dx >= 240) { 
     dx = dx - 240; 
    } 
    console.log(dx + ',' + dy); //Seems to print all positions ok 
}