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ThreeJS: Raytracer Example
How to access individual objects on the canvas used by THREE.js.
This code will create a scene and access the individual objects created using the mouse.
Create the HTML file index.html and paste this code into it. Note the comments in the file. This HTML/JavaScript file can be run from this site. Dowload the three.min.js file here: THREEJS.zip
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Raycaster Example</title>
<style>
body {
margin: 0;
padding: 0;
height: 100vh;
}
canvas {
display: block;
width: 100%;
height: 100vh;
}
</style>
</head>
<body>
<canvas></canvas>
<script src="/js/three.min.js"></script>
<script type="text/javascript">
(function () { // NOTE: three dancing balls example
var canvas = document.getElementsByTagName("canvas")[0];
// NOTE: create the scene to place objects in
var scene = new THREE.Scene();
scene.background = new THREE.Color(0x6699cc); // NOTE: make the background blue for the sky
scene.matrixWorldAutoUpdate = true;
// NOTE: the width and height of the parent element; this information is static and should be updated when the browser window is resized
var size = {
width: canvas.offsetWidth,
height: canvas.offsetHeight
};
// NOTE: issue these statements when resizing the window
// camera.aspect = size.width / size.height;
// camera.updateProjectionMatrix();
// renderer.setPixelRatio(window.devicePixelRatio);
// renderer.setSize(size.width, size.height);
// NOTE: create the camera with 53 degree field of view; this is how the scene is viewed by the user
var camera = new THREE.PerspectiveCamera(53, size.width / size.height, 1, 5000);
// NOTE: position the camera in space a bit
camera.position.z = 5;
var renderer = new THREE.WebGLRenderer({
canvas: canvas
});
renderer.shadowMap.enabled = true;
renderer.setPixelRatio(window.devicePixelRatio);
renderer.setSize(size.width, size.height);
renderer.render(scene, camera);
// NOTE: create the Raytracer
var raycaster = new THREE.Raycaster();
var mouse = new THREE.Vector2();
var sphereGeometry = new THREE.SphereGeometry(1.75, 32, 32);
// NOTE: create three spheres
var sphere1 = new THREE.Mesh(sphereGeometry, new THREE.MeshLambertMaterial({ color: 0xeeeeee }));
sphere1.position.x = sphere1.position.y = 0;
sphere1.position.z = -50;
sphere1.receiveShadow = true;
sphere1.castShadow = true;
scene.add(sphere1);
var sphere2 = new THREE.Mesh(sphereGeometry, new THREE.MeshLambertMaterial({ color: 0xeeeeee }));
sphere2.position.x = sphere2.position.y = 0.5;
sphere2.position.z = -25;
sphere2.receiveShadow = true;
sphere2.castShadow = true;
scene.add(sphere2);
var sphere3 = new THREE.Mesh(sphereGeometry, new THREE.MeshLambertMaterial({ color: 0xeeeeee }));
sphere3.position.x = sphere3.position.y = 0.5;
sphere3.position.z = -25;
sphere3.receiveShadow = true;
sphere3.castShadow = true;
scene.add(sphere3);
// NOTE: create the ground
var plane = new THREE.Mesh(new THREE.PlaneGeometry(1000, 1000), new THREE.MeshLambertMaterial({ color: 0x00FF00 }));
plane.position.x = 0;
plane.position.y = 0;
plane.position.z = -50;
plane.rotation.x = 4.75;
plane.receiveShadow = true;
scene.add(plane);
var light = new THREE.PointLight(0xffffff, 2);
light.position.set(0,30,0);
window.light = light;
light.castShadow = true;
scene.add(light);
scene.add(new THREE.AmbientLight(0xffffff, .4));
var handler = function (element, type, func) {
if (element.addEventListener) {
element.addEventListener(type, func, false);
} else if (window.attachEvent) {
element.attachEvent("on" + type, func);
} else {
element["on" + type] = func;
}
};
// NOTE: this function will set the color to red when hovering over the ball
handler(window, "mousemove", function (event) {
event.preventDefault();
mouse.x = (event.clientX / window.innerWidth) * 2 - 1;
mouse.y = - (event.clientY / window.innerHeight) * 2 + 1;
raycaster.setFromCamera(mouse, camera);
var intersects = raycaster.intersectObjects(scene.children, true);
for(var i = 0; i < intersects.length; i++) {
if(intersects[i].object !== plane) {
intersects[i].object.material.color.set(0xff0000);
setTimeout(function (obj) {
obj.material.color.set(0xeeeeee);
}, 1000, intersects[i].object);
}
}
});
// NOTE: this function will set the color to blue when the ball is clicked; try not to move the mouse at the same time
handler(window, "click", function (event) {
event.preventDefault();
mouse.x = (event.clientX / window.innerWidth) * 2 - 1;
mouse.y = - (event.clientY / window.innerHeight) * 2 + 1;
raycaster.setFromCamera(mouse, camera);
var intersects = raycaster.intersectObjects(scene.children, true);
for(var i = 0; i < intersects.length; i++) {
if(intersects[i].object !== plane) {
intersects[i].object.material.color.set(0x0000ff);
setTimeout(function (obj) {
obj.material.color.set(0xeeeeee);
}, 1000, intersects[i].object);
}
}
});
// NOTE: MUST HAVE AN ANIMATE FUNCTION
var animate = function () {
var time = Date.now(); // NOTE: this could also be the scroll position
sphere1.position.x = Math.cos(time / 200 + 10.0);
sphere1.position.y = Math.sin(time / 1000 + 10.0) + 5;
sphere1.position.z = Math.sin(time / 200 + 10.0) - 10;
sphere2.position.x = Math.cos(time / 1000 + 10.0) * 1.2;
sphere2.position.y = Math.sin(time / 200 + 10.0) * 1.2 + 5;
sphere3.position.x = Math.cos(time / 1000 + 10.0) * 1.5 + 6;
sphere3.position.y = Math.sin(time / 1000 + 10.0) * 1.5 + 7;
requestAnimationFrame(animate);
renderer.render(scene, camera);
};
animate();
})();
</script>
</body>
</html>
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