canvas - 调试threejs raycaster鼠标坐标

Question

我制作了一个光线转换器来与 Canvas 内的某个对象相交。如果 Canvas 在窗口浏览器中单独存在，则效果很好，但如果我将 Canvas 放在其他某个 GUI 中，则它不会相交，因此 Canvas 的位置不同。我认为这是鼠标坐标的问题。我该如何调试它？如果我知道鼠标坐标，我怎么知道 Canvas 的坐标是什么？

function getPosition(event) {
// TODO: add the border of the canvas
var x = new Number();
var y = new Number();

if (event.x != undefined && event.y != undefined) {
      x = event.x;
      y = event.y;
 } else {
      // Firefox method to get the position
      x = event.clientX + document.body.scrollLeft +
          document.documentElement.scrollLeft;
      y = event.clientY + document.body.scrollTop +
          document.documentElement.scrollTop;
 }

 x -= canvas.offsetLeft;
 y -= canvas.offsetTop;

 return {x: x, y: y};    
}

Answer 1

你需要的是:

// getBoundingClientRect() returns the element's position relative to the browser's visible viewport.
// clientX/Y returns the mouse position relative to the browser's visible viewport.
// we then just have to find the difference between the two to get the mouse position in "canvas-space"

var canvasPosition = renderer.domElement.getBoundingClientRect();

var mouseX = event.clientX - canvasPosition.left;
var mouseY = event.clientY - canvasPosition.top;

var mouseVector = new THREE.Vector2 (
        2 * (mouseX / window.innerWidth) - 1,
    1 - 2 * (mouseY / window.innerHeight));

然后你使用 mouseVector为交叉点。