【温故知新】——BABYLON.js学习之路·前辈经验（一）

项目实践中摸索到有关BABYLON的学习路径和问题解决方法整理来自网络

一、快速学习BABYLON

1. 阅读Babylon[基础教程](http://doc.babylonjs.com/babylon101/)

2. 阅读[一些BABYLON的新特性](http://doc.babylonjs.com/features/)
3. 阅读[代码片段](http://doc.babylonjs.com/samples)
4. 一些[更深入的教程详解](http://doc.babylonjs.com/how_to/)
5. [在游乐场玩耍](http://doc.babylonjs.com/playground/)

二、需要掌握的基本技能

1. engine,scene等创建，抗锯齿，像素比，深度缓冲区等配置项

2. 灯光的创建，基本属性，作用域
3. 相机的创建，基本属性，多相机的切换，绑定等
4. 材质的创建，不同纹理类型等
5. 场景中的元素，雾化，天空盒，阴影，地形图，世界坐标系，本地坐标系等
6. 事件，actionManager,onPointerDownObservable,pick,pickWithRay,
   onViewMatrixChangedObservable,onLightRemovedObservable等基本事件
7. UI

三、项目开发中遇到的一些问题及重点功能

# 灯光

//设置作用物体
light.includedOnlyMeshes
//设置排除物体
light.excludedMeshes

# 相机
1、相机多个动画的正确顺序

targetScreenOffet->target->beta->alpha->radius

2、相机运动触发的事件

camera.onViewMatrixChangedObservable

3、漫游相机定制跳跃转向碰撞等功能

//有两种方法可以根据世界矢量进行碰撞位移
//1.
camera._collideWithWorld(camera.getFrontPosition(10).subtract(camera.position))
//2.
camera.cameraDirection.addInPlace(camera._transformedDirection);
 
//如跳跃，则相对世界向上
scene.activeCamera.cameraDirection.addInPlace(new BABYLON.Vector3(0, 4, 0));
//重力回到地面
camera._needMoveForGravity = true;
//定制位移方向
var speedXX=camera._computeLocalCameraSpeed()*(左右惯性因子*panel) 
var speed=camera._computeLocalCameraSpeed()*(前后惯性因子*panel) 
camera._localDirection.copyFromFloats(speedX, 0, speedZ);
camera.getViewMatrix().invertToRef(camera._cameraTransformMatrix);
BABYLON.Vector3.TransformNormalToRef(camera._localDirection, camera._cameraTransformMatrix, camera._transformedDirection);
camera.cameraDirection.addInPlace(camera._transformedDirection);
//定制旋转方向
camera.rotation.x=(beta惯性因子*panel)
camera.rotation.y=(alpha惯性因子*panel)

# 重力

//添加重力
scene.gravity = new BABYLON.Vector3(0, -9.81, 0);
camera.applyGravity = true;
//添加碰撞
scene.collisionsEnabled = true;
camera.checkCollisions = true;
ground.checkCollisions = true;
box.checkCollisions = true;
//相机碰撞椭圆体
camera.ellipsoid = new BABYLON.Vector3(.5, 1, .5);
//arcRotateCamera的碰撞椭圆体
camera.collisionRadius =new BABYLON.Vector3(0.5, 0.5, 0.5)
//防止向上跳后无法落地
camera._needMoveForGravity = true;
//物体碰撞
mesh.moveWithCollisions(vec3);
//使用webworker运行碰撞检测
scene.workerCollisions = true|false

## 第二视图

var camera = new BABYLON.ArcRotateCamera("Camera", 0, 0, 0, BABYLON.Vector3.Zero(), scene);
camera.setPosition();
var followCamera = new BABYLON.FollowCamera("follow", new BABYLON.Vector3(400, 500, 1000), scene, ground)
followCamera.radius = 0
followCamera.heightOffset = 400;
scene.activeCameras.push(followCamera);
scene.activeCameras.push(camera);
followCamera.viewport = new BABYLON.Viewport(0, 0, 0.3, 0.3)
camera.viewport = new BABYLON.Viewport(0, 0.3, 1, 0.7)

## 四元数转换为欧拉角

sphere2.lookAt(sphere.position)
camera.position=sphere2.position;
camera.rotation.x=-sphere2.rotationQuaternion.toEulerAngles().x;
camera.rotation.y=sphere2.rotationQuaternion.toEulerAngles().y+Math.PI;
camera.rotation.z=sphere2.rotationQuaternion.toEulerAngles().z;

## 漫游相机和旋转相机的转换

旋转相机 -> 漫游相机

var radiusv3 = pickInfo.pickedPoint
var radius = radiusv3.length();
var alpha = Math.acos(radiusv3.x / Math.sqrt(Math.pow(radiusv3.x, 2) + Math.pow(radiusv3.z, 2)));
 if (radiusv3.z < 0) {
      alpha = 2 * Math.PI - alpha;
}
var beta = Math.acos(radiusv3.y / radius);

漫游相机-> 旋转相机

var radiusv3 = zxz.camera2.position;
var radius = radiusv3.length();
var alpha = Math.acos(radiusv3.x / Math.sqrt(Math.pow(radiusv3.x, 2) + Math.pow(radiusv3.z, 2)));
if (radiusv3.z < 0) {
    alpha = 2 * Math.PI - alpha;
}
var beta = Math.acos(radiusv3.y / radius);

# 材质

1、材质特殊参数

material.maxSimultaneousLights //最多可接受灯光个数，默认4个
material.useLogarithmicDepth 
material.needDepthPrePass      //深度判断
material.transparencyMode=2;

2、 dynamicTexture

var dynamicTexture = new BABYLON.DynamicTexture("DynamicTexture", {width:50,height:50}, scene, true);
dynamicTexture.hasAlpha = true;
dynamicTexture.drawText(text, 10, 50, "bold 100px Arial", color , "transparent", true,true);
var plane = new BABYLON.Mesh.CreatePlane("TextPlane", size, scene, true);
plane.material = new BABYLON.StandardMaterial("TextPlaneMaterial", scene);
plane.material.backFaceCulling = false;
plane.material.specularColor = new BABYLON.Color3(0, 0, 0);
plane.material.diffuseTexture = dynamicTexture;

3、镜面反射材质

Material.diffuseColor = new BABYLON.Color3(0.4, 0.4, 0.4);
Material.reflectionTexture = new BABYLON.MirrorTexture("mirror", 1024, scene, true); //Create a mirror texture
Material.reflectionTexture.mirrorPlane = new BABYLON.Plane(0, -1.0, 0, -10.0);
Material.reflectionTexture.renderList = [ground,skybox];
Material.reflectionTexture.level = 0.6;//Select the level (0.0 > 1.0) of the reflection

4、探针

var box = BABYLON.Mesh.CreateBox("box", 5000, scene);
//直接贴反射贴图
//material.reflectionTexture = new BABYLON.CubeTexture('img/bg/4', scene);
//box.material = new BABYLON.StandardMaterial("boxMaterial", scene);
//box.material.reflectionTexture = new BABYLON.CubeTexture('img/bg/4', scene);
//box.material.reflectionTexture.coordinatesMode = BABYLON.Texture.SKYBOX_MODE;
//box.material.backFaceCulling = false;
//box.rotation.z = Math.PI / 2;

var probe = new BABYLON.ReflectionProbe("main", 512, scene);
probe.renderList.push(yellowSphere);
probe.renderList.push(greenSphere); 
probe.renderList.push(blueSphere); 
probe.renderList.push(mirror); 
mainMaterial.diffuseColor = new BABYLON.Color3(1, 0.5, 0.5); 
mainMaterial.reflectionTexture = probe.cubeTexture;
mainMaterial.reflectionFresnelParameters = new BABYLON.FresnelParameters();
mainMaterial.reflectionFresnelParameters.bias = 0.02;

5、菲涅尔

//所有菲涅尔类型
StandardMaterial.diffuseFresnelParameters
StandardMaterial.reflectionFresnelParameters
StandardMaterial.opacityFresnelParameters
StandardMaterial.emissiveFresnelParameters
StandardMaterial.refractionFresnelParameters
//用法
var saturne = BABYLON.Mesh.CreateSphere("saturne", 16, 80, scene);
var saturne_material = new BABYLON.StandardMaterial("saturne_material", scene);
saturne_material.reflectionTexture = new BABYLON.CubeTexture("../../assets/skybox/nebula", scene);

saturne_material.reflectionFresnelParameters = new BABYLON.FresnelParameters();
saturne_material.reflectionFresnelParameters.bias = 0.2;

saturne_material.emissiveFresnelParameters = new BABYLON.FresnelParameters();
saturne_material.emissiveFresnelParameters.bias = 0.6;
saturne_material.emissiveFresnelParameters.power = 4;
saturne_material.emissiveFresnelParameters.leftColor = BABYLON.Color3.White();
saturne_material.emissiveFresnelParameters.rightColor = new BABYLON.Color3(0.6, 0.6, 0.6);

saturne.material = saturne_material;

# 动画
1. 创建animation对象

var animation = new BABYLON.Animation(name, targetProperty, framePerSecond, dataType, loopMode, enableBlending);

2. 绑定键值对

animation.setKeys([{frame:0,value:0},...])

3. 设置运动函数

var bezierEase = new BABYLON.BezierCurveEase(.97, .2, 0, .58);
bezierEase.setEasingMode(BABYLON.EasingFunction.EASINGMODE_EASEOUT);
animation.setEasingFunction(bezierEase);

4. 将动画对象push到mesh的animations属性中

mesh.parent.animations.push(animationPosition);

5. 开始运行动画

var animatable=beginAnimation(target, from, to, loop, speedRatio, onAnimationEnd, animatable)
animatable.pause()   //暂停
animatable.restart() //从暂停的地方开始播放
animatable.stop()    //停止动画，不能恢复
animatable.reset()   //重新开始，从0 frame的地方，不管循环模式

** 注意:
* bug ：从0到0 整个场景会抖动
* 由3Dmax导入动画，直接开始运行，bug:如果scene.stopAnimation，下次begin一定要通过事件才能正常触发。
* 就算没有给对象设置动画对象，但是开始运行动画了，也能通过scene.getAnimatableByTarget(mesh)获取到animatable对象(虽然animations为空数组)
* 如果loop 设置为了ture，那么根据loopMode来进行循环，并且永远处于运动状态，不会触发onAnimationEnd回调函数，除非stopAnimation或者再运行一遍beginAnimation，
或者使用 BABYLON.Animation.CreateAndStartAnimation(且使用ANIMATIONLOOPMODE_CONSTANT模式)
* 如果loop设置为false,动画只执行一次，然后触发onAnimationEnd回调函数
* 在动画运行过程中如果手动更新了animation.setKeys()，那么继续当前的动画且currentFrame不变，但是更新了keys，也就是跳到了新的keys的当前frame画面，所以会有一个突变的卡顿现象
* 如果当前处于运动状态，又运行了一遍beginAnimation，那么会stopAnimation，并重置当前帧数，可以解决卡顿现象。
* animatable.stop直接停止运动状态，restart结束暂停状态，不会变化位置，如果stop等停止了运动状态，restart无效，reset是直接回到动画刚开始的位置
* createAndStartAnimation不会打断其他动画，但是beginAnimation会打断所有animation包括createAndStartAnimation
* beginAnimation会打断createAndStartAnimation,createAndStartAnimation不会打断beginAnimation

# 粒子

1、发射方向类型
particleSystem.particleEmitterType = new BABYLON.SphereParticleEmitter(10,false);
//或者
particleSystem.createSphereEmitter(10);//GPUParticle没有这个API

2、子粒子，放烟花
particleSystem.subEmitters = [particleSystem,..]
3、members
particleSystem.disposeOnStop=true;

# mesh
1、facet Data

//获得三角形的中心
mesh.getFacetPosition(faceId)

//the 50th facet local position
var localPositions = mesh.getFacetLocalPositions(); // returns the array of facet positions in the local space
var localPos = localPositions[50]; 

//normal
var norm = mesh.getFacetNormal(faceId);

//
var localNormals = mesh.getFacetLocalNormals(); // returns the array of facet normals in the local space
var localPos = localNormals[50]; // Vector3 : the 50th facet local position

//All the methods dealing with the world coordinates use the mesh world matrix. As you may know, this matrix is automatically computed on the render call.
If you've just moved, scaled or rotated your mesh before calling the facetData methods using the world values and you're not sure about this, you can ever force the world matrix computation.
mesh.rotate.y += 0.2; // the mesh will be rotated on the next render call, but I need a rotated normal
mesh.computeWorldMatrix(true); // force the world matrix computation
var norm = mesh.getFacetNormal(50); // returns the world normal of the mesh 50th facet

2、获取轴心

//如果之前有freeze矩阵，则需要先重新计算
mesh.computeWorldMatrix(true)
mesh.getAbsolutePivotPoint()

3、设置本身轴偏差

mesh.setPivotPoint(vec3)

4、画线

var lines=new BABYLON.Mesh.CreateLines("line",[v0,v1,v2,v3],scene)
//画线默认是以gl.LINES方法绘画，例子中虽然只传入了4个顶点，但是默认0,1 1,2 2,3 
//颜色：lines.color

5、自定义geometry

//简单的使用verticesData
mesh.setVerticesData(kind:string,data:array,updatable:boolean,stride:number) 
//demo:
mesh.setVerticesData("position", positions, true)
//stride :position,normal 默认3,uv 默认2
//或者使用buffer,可以更多的配置offset,size,stride等选项
mesh.setVerticesBuffer(new vertexBuffer(engine,data:array,kind:string,updatable:boolean,postponeInternalCreation:boolean,stride:number，instanced：Boolean，offset：number,size:number))
//demo:
var aRotation = new Float32Array(pointLength*2);
mesh.setVerticesBuffer(new BABYLON.VertexBuffer(engine, aRotation, "aRotation", true, false, 2));
//最后必须设置索引
mesh.setIndices(Array)

6、使用自定义的attribute传入着色器

var material = new BABYLON.ShaderMaterial("particle", scene, "./js/particle",
{
  uniforms: ["worldViewProjection", "uTime", "uTranslation", "axis", "alpha", /*"resolution",*/ "pointSize", "baseColor", /*"rebuilding",*/ "status", "scatter", "uvMode", "mobile"],
  attributes: ["position", "uv", "aRotation", "aAnimation", "raxis"],
  needAlphaBlending:true //通过material.alphaMode=来设置混合模式
});
material.fillMode = 2;
material.setFloat("uTime", 0.);
material.setVector3("axis", new BABYLON.Vector3(0, 1, 0));
material.setVector3("uTranslation", new BABYLON.Vector3(0, 500, 0));
material.setColor3("baseColor", new BABYLON.Color3(1, 1, 1));
material.setFloat("status", .5);
material.setFloat("scatter", 0);
material.setFloat("uvMode", 0);

7、一般用到的创建着色器程序的两种方法

BABYLON.Effect.ShadersStore["customVertexShader"]= "/r/n"+
"precision highp float;/r/n"+

"attribute vec3 position;/r/n"+
"attribute vec2 uv;/r/n"+

"uniform mat4 worldViewProjection;/r/n"+

"varying vec2 vUV;/r/n"+

"void main(void) {/r/n"+
" gl_Position = worldViewProjection * vec4(position, 1.0);/r/n"+

" vUV = uv;/r/n"+
"}/r/n";

BABYLON.Effect.ShadersStore["customFragmentShader"]= "/r/n"+
"precision highp float;/r/n"+

"varying vec2 vUV;/r/n"+

"uniform sampler2D textureSampler;/r/n"+

"void main(void) {/r/n"+
" gl_FragColor = texture2D(textureSampler, vUV);/r/n"+
"}/r/n";


//----------------------------------------------------------------------
var shaderMaterial = new BABYLON.ShaderMaterial("shader", scene, {
vertex: "custom",
fragment: "custom",
},
{
attributes: ["position", "normal", "uv"],
uniforms: ["world", "worldView", "worldViewProjection", "view", "projection"]
});

var mainTexture = new BABYLON.Texture("amiga.jpg", scene);
shaderMaterial.setTexture("textureSampler", mainTexture);

View Code

//方法一. BABYLON.Effect.ShadersStore["customVertexShader"]
var shaderMaterial = new BABYLON.ShaderMaterial("shader", scene, {
    vertex: "custom",
    fragment: "custom",
},
{
    attributes: ["position", "normal", "uv"],
    uniforms: ["world", "worldView", "worldViewProjection", "view", "projection"]
});

//方法二.创建单独的文件basename.vertex.fx和basename.fragment.fx
var cloudMaterial = new BABYLON.ShaderMaterial("cloud", scene, "./basename",
{
    attributes: ["position", "uv"],
    uniforms: ["worldViewProjection"],
    needAlphaBlending:true //通过material.alphaMode=来设置混合模式
});

## 传参方法

setTexture，setFloat，setFloats，setColor3，setColor4，setVector2，setVector3，setVector4，setMatrix
attributes: mesh.setVerticesBuffer(new BABYLON.VertexBuffer(engine, aRotation, "aRotation", true, false, 2));

## BABYLON默认传入的参数

1、自动传入的uniform变量

world，
view，
projection，
worldView，
worldViewProjection
cameraPosition

2、自动传入的attribute变量

position
normal
uv
uv2

## 通过索引创建submesh

BABYLON.SubMesh.CreateFromIndices(subMesh.materialIndex, offset, Math.min(subdivisionSize, totalIndices - offset), mesh);

## CSG

union 相加
subtract 相减`
intersect 相交
var sphereCSG = BABYLON.CSG.FromMesh(sphere);
sphereCSG.subtractInPlace(BABYLON.CSG.FromMesh(cylinderMesh));
sphereCSG.toMesh("bowling ball", sphere.material, scene, false);
copyTransformAttributes(csg)

默认是源CSG的变换矩阵，如果需要改变，比如intersect的CSG，那么可以设置相交部分的CSG为变换矩阵，轴就在新建物体的原点

## polygonMeshBuilder
通过path2创建的polygon是动态创建的，会根据scaling来增加顶点

# 场景
1、自己创建天空盒

var skybox = BABYLON.Mesh.CreateBox("skyBox", 100.0, scene);
var skyboxMaterial = new BABYLON.StandardMaterial("skyBox", scene);
skyboxMaterial.backFaceCulling = false;
skyboxMaterial.reflectionTexture = new BABYLON.CubeTexture("../../Assets/skybox/skybox", scene);
skyboxMaterial.reflectionTexture.coordinatesMode = BABYLON.Texture.SKYBOX_MODE;
skyboxMaterial.diffuseColor = new BABYLON.Color3(0, 0, 0);
skyboxMaterial.specularColor = new BABYLON.Color3(0, 0, 0);
skybox.material = skyboxMaterial;
skybox.material.disableLighting = true;
skybox.infiniteDistance = true;
//天空盒模糊
skyMaterial.roughness = 6;

2、利用API创建场景天空盒，将作用于场景中所有的物体

scene.environmentTexture=new BABYLON.CubeTexture("/assets/textures/SpecularHDR-env.dds");
var envTexture = new BABYLON.CubeTexture("/assets/textures/SpecularHDR.dds", scene);
scene.createDefaultSkybox(envTexture, pbr?:boolean, scale?:number,blur?:number);

3、利用API生成默认场景

var helper=scene.createDefaultEnvironment(opt);
helper.setMainColor(BABYLON.Color3.Teal());
opt:
createGround: Specifies wether or not to create a ground.
groundSize: Specifies the ground size (if sizeAuto is false).
groundTexture: The texture used on the ground (Default to Babylon CDN).
groundColor: The color mixed in the ground texture by default.
enableGroundShadow: Enables the ground to receive shadows.
groundShadowLevel: Helps preventing the shadow to be fully black on the ground.
enableGroundMirror: Creates a mirror texture attach to the ground.
createSkybox: Specifies wether or not to create a skybox.
skyboxSize: Specifies the skybox size (if sizeAuto is false).
skyboxTexture: The texture used on the skybox (Default to Babylon CDN).
skyboxColor: The color mixed in the skybox texture by default.
sizeAuto: Compute automatically the size of the elements to best fit with the scene.
setupImageProcessing: Sets up the inmage processing in the scene.
environmentTexture: The texture used as your environment texture in the scene (Default to Babylon CDN).
cameraExposure: The value of the exposure to apply to the scene.
cameraContrast: The value of the contrast to apply to the scene.
toneMappingEnabled: Specifies wether or not tonemapping should be enabled in the scene.

## 雾化

scene.fogMode = BABYLON.Scene.FOGMODE_EXP;
scene.fogDensity = 0.02;
scene.fogColor = scene.clearColor;
material.fogEnabled;

## 地形图

BABYLON.Mesh.CreateGroundFromHeightMap("ground", "worldHeightMap.jpg", width:200, height:200, subdivision:250, minHeight:0, maxHeight:10, scene, updatable:false, onReady:successCallback);
getHeightAtCoordinates(x,z)

## 阴影

var shadowGenerator=new BABYLON.ShadowGenerator(阴影贴图的大小：1024,light);
//产生阴影的物体列表
shadowGenerator.getShadowMap().renderList.push(box);

//软化阴影
//泊松抽样
shadowGenerator.usePoissonSampling = true;
//指数阴影贴图
shadowGenerator.useExponentialShadowMap = true;
shadowGenerator.depthScale=50
//模糊指数阴影图
shadowGenerator.useBlurExponentialShadowMap = true;
//模糊质量
shadowGenerator.useKernelBlur = true;
shadowGenerator.blurScale = 1;
shadowGenerator.blurKernel = 60;
//接收阴影
plane.receiveShadows=true;
//阴影计算默认1秒60次，静态阴影改为1次就可以了;
shadowGenerator.getShadowMap().refreshRate =BABYLON.RenderTargetTexture.REFRESHRATE_RENDER_ONCE //（0）We need to compute it just once
//让灯不要重新计算阴影位置
light.autoUpdateExtends = false;
//取消泊松亮斑
shadowGenerator.bias=0.001;
//webGL2.0
usePercentageCloserFiltering=true;

## 世界坐标系与本地坐标系
1. lookAt(vector)是以z轴指向vector这个点的位置，使用这个值后，会清零rotation,并将本地轴的信息存放在rotationQuaternion中。
2. 本地轴默认为世界坐标系(左手坐标系).
3. 若要使用本地坐标系，可以使用

* position
* rotation
* translate(vector,distance,BABYLON.Space.LOCAL)
* rotate(vector,distance,BABYLON.Space.LOCAL)

4. 如果需要使用世界坐标系

* rotate(vector,distance,BABYLON.Space.WORLD)
* translate(vector,distance,BABYLON.Space.WORLD)

5. 位移(position,translate)都是沿着世界坐标系或者父元素的本地坐标系进行位移，若要沿着自己的本地轴进行位移，则

* locallyTranslate(vector)

6. 如果设置了rotationQuaternion,那么本地轴存放在rotationQuaternion中（如果3DSMAX中导出轴不是世界坐标系，那么本地轴也存放在这里，否则的话这个值为undefined

## 优化
1. material.freeze();

scene.freezeMaterials();

冻结后，即使更改材质的属性，着色器也将保持不变。您将不得不解冻它来更新内部着色器：

material.unfreeze();
scene.unfreezeMaterials();

2. 默认情况下，Babylon.js使用索引的网格，其中顶点可以由面部重用。当顶点重用率低时，如果顶点结构相当简单（就像一个位置和一个正常的），那么你可能需要展开顶点并停止使用索引

mesh.convertToUnIndexedMesh();

例如，这对于立方体来说非常有效，其中更有效地发送32个位置而不是24个位置和32个索引。

3. 默认情况下，Babylon.js将适应设备比例，以便在高DPI设备上产生最佳质量。
缺点是这可能会在低端设备上花费很多。您可以使用Engine构造函数的第四个参数关闭它：

var engine = new BABYLON.Engine(canvas, antialiasing, null, false);

我们也可以通过设置精度来降低FPS消耗

engine.setHardwareScalingLevel(1~10)

4. BABYLON.SceneOptimizer.OptimizeAsync(scene)；
等同于：

BABYLON.SceneOptimizer.OptimizeAsync(scene, BABYLON.SceneOptimizerOptions.ModerateDegradationAllowed(),
function() {
// On success
}, function() {
// FPS target not reached
})

5. 当mesh的顶点数量太多，检测碰撞时候最好开启子网格，子网格进行检测

mesh.subdivide(x)
mesh.createOrUpdateSubmeshesOctree(capacity, maxDepth)
mesh.useOctreeForCollisions
mesh.useOctreeForPicking
mesh.useOctreeForRenderingSelection
//var octree=scene.createOrUpdateSelectionOctree();
//for(var i=0;i<scene.meshes.length;i++){
// octree.dynamicContent.push(scene.meshes[i])
//}

6.createInstance();

synchronizeInstances()

实例对象的LOD继承sourceMesh的LOD

7.LOD
LOD的对象不管原来的位置，旋转是什么，都以sourceMesh的位置，旋转为准。

addLODLevel();

8.简化网格，生成不同faces的LOD

simplify(settings, parallelProcessing, simplificationType, successCallback) → void
//scene.meshes[0].simplify([{ quality: 0.1, distance: 10000 }],
// true, BABYLON.SimplificationType.QUADRATIC, function() {
// alert("LOD finisehd, let's have a beer!");
// });

## 广告板

plane.billboardMode = BABYLON.Mesh.BILLBOARDMODE_Y;

## 判断是否为手机

var os = function() {
     var ua = navigator.userAgent,
     isWindowsPhone = /(?:Windows Phone)/.test(ua),
     isSymbian = /(?:SymbianOS)/.test(ua) || isWindowsPhone,
     isAndroid = /(?:Android)/.test(ua),
     isFireFox = /(?:Firefox)/.test(ua),
     isChrome = /(?:Chrome|CriOS)/.test(ua),
     isTablet = /(?:iPad|PlayBook)/.test(ua) || (isAndroid && !/(?:Mobile)/.test(ua)) 
 || (isFireFox && /(?:Tablet)/.test(ua)),
     isPhone = /(?:iPhone)/.test(ua) && !isTablet,
     isPc = !isPhone && !isAndroid && !isSymbian;
return {
     isTablet: isTablet,
     isPhone: isPhone,
     isAndroid : isAndroid,
     isPc : isPc
   };
}();

## actionManager

1.mesh.actionManager = new BABYLON.ActionManager(scene);
2.mesh.actionManager.registerAction(new BABYLON.InterpolateValueAction(BABYLON.ActionManager.OnPickTrigger, light, "diffuse", BABYLON.Color3.Black(), 1000));
3.mesh.actionManager.registerAction(new BABYLON.ExecuteCodeAction(BABYLON.ActionManager.OnPointerOverTrigger, function(){
}))
actionmanager{
additionalData:
source:
pointerX:
pointerY:
sourceEvent:
}

## onPointerObservable

scene.onPointerObservable.add(function(e){
    e.type:1,
    //1.onmousedown
    //2:onmouseup
    //4:onmousemove
    e.event:sourceevent,

    e.pickInfo:{
          hit:
          pickedMesh:
          pickedPoint:vec3
    }
})

## 辉光

//mainTextureRatio略微调大点，解决辉光闪烁
var hl = new BABYLON.HighlightLayer("dianchiMat", scene, {mainTextureRatio: 1.5});

### toDataURL

//先进行设置
var engine = new BABYLON.Engine(canvas, antialiasing, {
preserveDrawingBuffer: true,
}, false);
canvas.toDateURL();

## GUI

var gui = BABYLON.GUI.AdvancedDynamicTexture.CreateForMesh(plane, 1024, 1024, false);
var control = new BABYLON.GUI.Image(plane.name + "_gui", "img/function" + (index + 1) + ".png");
gui.addControl(control)
control.width
usableWidth = width - paddingLeft - paddingRight
control.left
control.top

## 获取模型的在画布上面的二维坐标

var mesh2d = BABYLON.Vector3.Project(mesh.position,
BABYLON.Matrix.Identity(),
scene.getTransformMatrix(),
camera.viewport.toGlobal(engine.getRenderWidth(), engine.getRenderHeight()));
console.log(mesh2d.y)
console.log(mesh2d.x)

在最小宽度为760所以小于760的尺寸如移动端必须使用百分比获取坐标

var mesh2d = BABYLON.Vector3.Project(mesh.position,
BABYLON.Matrix.Identity(),
scene.getTransformMatrix(),
camera.viewport.toGlobal(engine.getRenderWidth(), engine.getRenderHeight()));
console.log(mesh2d.y/engine.getRenderHeight()*100+"%")
console.log(mesh2d.x/engine.getRenderWidth()*100+"%")

var options = new BABYLON.SceneOptimizerOptions(50, 2000);
options.addOptimization(new BABYLON.HardwareScalingOptimization(0, 1));

原文地址：https://www.cnblogs.com/ljq66/p/9896578.html

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WEBGL学习网 » 【温故知新】——BABYLON.js学习之路·前辈经验（一）