three.js学习：三维空间下的直线

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>测试</title>
    <script src="js/three.min.js"></script>
    <style>
        html, body {
            width: 100%;
            height: 100%;
            margin: 0;
            padding: 0;
            /*background-color: blue;*/
        }
    </style>
</head>
<body>
<canvas></canvas>
</body>
<script src="js/chapter2.1.js"></script>
</html>

chapter2.1.js

1、步骤概述：初始化渲染器 > 初始化相机 > 初始化场景 > 建立几何图形并添加到场景中 > 渲染

function threeStart() {
    initThree(); 
    initCamera();
    initScene();
    initObject();
    renderer.clear();
    renderer.render(scene, camera);
}
threeStart();

2、初始化渲染器

var canvas = document.querySelector("canvas");
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;

var renderer;
function initThree() {
    renderer = new THREE.WebGLRenderer({
        canvas : canvas,
        antialias : true
    });
    renderer.setSize(window.innerWidth, window.innerHeight);
    renderer.setClearColor(0xffffff, 1);
}

3、初始化相机

var camera;
function initCamera() {
    camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
    camera.position.x = 0;
    camera.position.y = 0;
    camera.position.z = 1000;
    camera.up.x = 0;
    camera.up.y = 1;
    camera.up.z = 0;
    camera.lookAt(0, 0, 0);
}

4、初始化场景

var scene;
function initScene () {
    scene = new THREE.Scene();
}

5、生成几何图行并添加到场景中

var line;
function initObject() {
    //定义两个顶点
    var p1 = new THREE.Vector3(-100, -100, 0);
    var p2 = new THREE.Vector3(100, 100, 0);

    var geometry = new THREE.Geometry();
    var material = new THREE.LineBasicMaterial({vertexColors:THREE.VertexColors });
    geometry.vertices.push(p1);
    geometry.vertices.push(p2);

    var color1 = new THREE.Color( 0x444444 ), color2 = new THREE.Color( 0xFF0000 );
    geometry.colors.push(color1, color2);
    line = new THREE.Line(geometry, material, THREE.LineSegments);
    scene.add(line);
}

执行效果：

因为实例化材质的时候，用了vertexColors:THREE.VertexColors参数，因此直线的颜色是根据顶点的颜色渐变的。

6、直线进阶：网格线

var canvas = document.body.querySelector("canvas");
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;

var renderer;

function initThree() {
    renderer = new THREE.WebGLRenderer({
        canvas: canvas,
        antialias: true
    });
    renderer.setSize(window.innerWidth, window.innerHeight);
    renderer.setClearColor(0xFFF000, 1.0);
}

var camera;

function initCamera() {
    camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 100000);
    camera.position.x = 0;
    camera.position.y = 0;
    camera.position.z = 1000;
    camera.up.x = 0;
    camera.up.y = 1;
    camera.up.z = 0;
    camera.lookAt(0, 0, 0);
}

var scene;

function initScene() {
    scene = new THREE.Scene();
}

var light;
function initLight() {
    light = new THREE.DirectionalLight(0xFF0000, 1.0, 0);
    light.position.set(10, 10, 20);
    scene.add(light);
}

var cube;

function initObject() {
    var geometry = new THREE.Geometry();
    geometry.vertices.push(new THREE.Vector3(-500, 0, 0));
    geometry.vertices.push(new THREE.Vector3(500, 0, 0));

    for (var i = 0; i <= 20; i++) {
        var line = new THREE.Line(geometry, new THREE.LineBasicMaterial({color: 0x000000, opacity: 0.2}));
        line.position.y = (i * 50) - 500;
        scene.add(line);

        var line2 = new THREE.Line(geometry, new THREE.LineBasicMaterial({color: 0x000000, opacity: 0.2}));
        line2.position.x = (i * 50) - 500;
        line2.rotation.z = 90 * Math.PI / 180;
        scene.add(line2);
    }
}

function threeStart() {
    initThree();
    initCamera();
    initScene();
    initLight();
    initObject();
    renderer.clear();
    renderer.render(scene, camera);
}
threeStart();

three.js学习：三维空间下的直线

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