BabylonJS - 网格

在本章中，我们将学习使用网格生成器创建不同的形状。我们已经在前面的一章中学习了如何创建形状。

不同之处在于，使用 meshbuilder 可以灵活地向形状添加颜色、图像。

使用 MeshBuilder 创建框

现在让我们看看如何使用 MeshBuilder 创建盒子。

演示

<!doctype html>
<html>
   <head>
      <meta charset = "utf-8">
      <title>BabylonJs - Basic Element-Creating Scene</title>
      <script src = "babylon.js"></script>
      <style>
         canvas {width: 100%; height: 100%;}
      </style>
   </head>

   <body>
      <canvas id = "renderCanvas"></canvas>
      <script type = "text/javascript">
         var canvas = document.getElementById("renderCanvas");
         var engine = new BABYLON.Engine(canvas, true);
         
         var createScene  = function() {
            var scene = new BABYLON.Scene(engine);
            scene.clearColor = new BABYLON.Color3(0, 0, 1);
            
            var camera = new BABYLON.ArcRotateCamera("Camera", 1, 0.8, 10, new BABYLON.Vector3(0, 0, 0), scene);
            camera.attachControl(canvas, true);

            var light = new BABYLON.HemisphericLight("light1", new BABYLON.Vector3(0, 1, 0), scene);
            light.intensity = 0.7;

            var pl = new BABYLON.PointLight("pl", BABYLON.Vector3.Zero(), scene);
            pl.diffuse = new BABYLON.Color3(1, 1, 1);
            pl.specular = new BABYLON.Color3(1, 1, 1);
            pl.intensity = 0.8;

            var mat = new BABYLON.StandardMaterial("mat1", scene);
            mat.alpha = 1.0;
            mat.diffuseColor = new BABYLON.Color3(0, 1, 0);
            
            var texture = new BABYLON.Texture("images/cube.png", scene);
            mat.diffuseTexture = texture;

            var hSpriteNb =  3;  // 3 sprites per raw
            var vSpriteNb =  2;  // 2 sprite raws

            var faceUV = new Array(6);
            for (var i = 0; i < 6; i++) {
               faceUV[i] = new BABYLON.Vector4(i/hSpriteNb, i/vSpriteNb, (i+1)/hSpriteNb, (i+1)/vSpriteNb);
            }

            var options = {
               width: 1.5,
               height: 1.5,
               depth: 1.5,
               faceUV: faceUV
            };

            var box = BABYLON.MeshBuilder.CreateBox("box", options, scene);
            box.material = mat;

            scene.registerBeforeRender(function() { 
               pl.position = camera.position;
            });
            return scene;
         };
         var scene = createScene();
         engine.runRenderLoop(function() {
            scene.render();
         });
      </script>
   </body>
</html>

输出

上面的代码行生成以下输出 -

对于上面的示例，我们使用了精灵图像，如下所示。它有水平 3 列和垂直 2 行。

在这个演示中，我们使用了一个名为cube.png的图像。图片存储在本地的images/文件夹中，也粘贴在下面以供参考。请注意，cube.png 是一个精灵图像，精灵图像是图像的集合。我们想在立方体上显示图像，因此希望立方体的所有侧面都在一起。您还可以下载您选择的类似精灵图像并在演示链接中使用。

createBox 构建器为您提供尺寸选项。

例如，

var box = BABYLON.MeshBuilder.CreateBox("box", options, scene);

演示

var hSpriteNb =  3;  // 3 sprites per raw ie colums horizontally as shown in the image

var vSpriteNb =  2;  // 2 sprite raws as shown in the image above.

var faceUV = new Array(6); // the cube has 6 sides so creating array for same.
for (var i = 0; i < 6; i++) {
   faceUV[i] = new BABYLON.Vector4(i/hSpriteNb, i/vSpriteNb, (i+1)/hSpriteNb, (i+1)/vSpriteNb);
}

var options = {
   width: 1.5,
   height: 1.5,
   depth: 1.5,
   faceUV: faceUV
};

这称为使用 createBox 方法将纹理应用到网格构建器。我们使用了图像cube.png，它具有水平 3 列和垂直 2 行。立方体或盒子有 6 个边。

为了应用纹理，我们使用选项参数。例如，

Var box = BABYLON.MeshBuilder.CreateBox ('box', options, scene);

我们定义了一个名为faceUV的数组，大小为6，它们是立方体的边。该数组将始终包含 Vector4 元素。每个 Vector4(x, y, z, w) 定义如下 -

x = 下底
y = V 底部
z = 乌托普
w = 顶峰

向量的范围是 [0, 1]。Ubottom 和 Vbottom 是纹理裁剪开始处的左下点的 2D 坐标。Utop、Vtop 是纹理裁剪结束的右上角点。

var hSpriteNb =  3;  // 3 sprites per raw
var vSpriteNb =  2;  // 2 sprite raws

var faceUV = new Array(6);
for (var i = 0; i < 6; i++) {
   faceUV[i] = new BABYLON.Vector4(i/hSpriteNb, i/vSpriteNb, (i+1)/hSpriteNb, (i+1)/vSpriteNb);
}

假设默认纹理（即给定的图像）应用于框的所有面。如果您只想更改框的 1 个面或 1 个边，您可以直接指定值，如下所示 -

var hSpriteNb =  3;  // 3 sprites per raw
var vSpriteNb =  2;  // 2 sprite raws

var faceUV = new Array(6);
faceUV[4] = new BABYLON.Vector4(0, 0, 1/hSpriteNb, 1/vSpriteNb);

例子

<!doctype html>
<html>
   <head>
      <meta charset = "utf-8">
      <title>BabylonJs - Basic Element-Creating Scene</title>
      <script src = "babylon.js"></script>
      <style>
         canvas {width: 100%; height: 100%;}
      </style>
   </head>
   
   <body>
      <canvas id = "renderCanvas"></canvas>
      <script type = "text/javascript">
         var canvas = document.getElementById("renderCanvas");
         var engine = new BABYLON.Engine(canvas, true);
         
         var createScene  = function() {
            var scene = new BABYLON.Scene(engine);
            scene.clearColor = new BABYLON.Color3(0, 0, 1);
            
            var camera = new BABYLON.ArcRotateCamera("Camera", 1, 0.8, 10, new BABYLON.Vector3(0, 0, 0), scene);
            camera.attachControl(canvas, true);

            var light = new BABYLON.HemisphericLight("light1", new BABYLON.Vector3(0, 1, 0), scene);
            light.intensity = 0.7;

            var pl = new BABYLON.PointLight("pl", BABYLON.Vector3.Zero(), scene);
            pl.diffuse = new BABYLON.Color3(1, 1, 1);
            pl.specular = new BABYLON.Color3(1, 1, 1);
            pl.intensity = 0.8;

            var mat = new BABYLON.StandardMaterial("mat1", scene);
            mat.alpha = 1.0;
            mat.diffuseColor = new BABYLON.Color3(0.8, 0.8, 0.8);
            
            var texture = new BABYLON.Texture("images/3d.png", scene);
            mat.diffuseTexture = texture;

            var hSpriteNb =  3;  // 3 sprites per raw
            var vSpriteNb =  2;  // 2 sprite raws

            var faceUV = new Array(6);
            faceUV[4] = new BABYLON.Vector4(0, 0, 1/hSpriteNb, 1/vSpriteNb);

            var options = {
               width:3,
               height:3,
               depth: 3,
               faceUV:faceUV
            };

            var box = BABYLON.MeshBuilder.CreateBox("box", options, scene);
            box.material = mat;

            scene.registerBeforeRender(function() { 
               pl.position = camera.position;
            });
            return scene;
         };
         var scene = createScene();
         engine.runRenderLoop(function() {
            scene.render();
         });
      </script>
   </body>
</html>

输出

上面的代码行生成以下输出 -

在此演示中，我们使用了名为 3d.png 的图像。图片存储在本地的images/文件夹中，也粘贴在下面以供参考。请注意 3d.png 是精灵图像；精灵图像是图像的集合。我们想要在立方体上显示图像，并且立方体的所有侧面都在一起。您还可以下载您选择的类似精灵图像并在演示链接中使用。

用于盒子的纹理 - images/3d.png

网状圆柱体

在本节中，我们将了解如何创建 MeshCylinder。

要创建MeshCylinder，您需要使用类BABYLON.MeshBuilder.CreateCylinder。

该类的参数如下 -

var meshcylinder = BABYLON.MeshBuilder.CreateCylinder("meshcylinder", {
   height: 3,
   diameter: 35,
   tessellation: 52
}, scene);

使用网格和网格构建器的 CreateCylinder 之间的区别是 - 您可以使用网格构建器中的选项。现在我们使用高度、直径和镶嵌作为传递给圆柱体的选项。我们使用带有线框的标准材料作为该网格的材料。检查浏览器中的输出并查看圆柱体。您可以在游戏中使用类似的结构，就像场景中旋转的轮子一样。

演示

<!doctype html>
<html>
   <head>
      <meta charset = "utf-8">
      <title>Babylon.js demo - Mesh Builder</title>
      <script src = "babylon.js"></script>
      <style>
         html,body,canvas { margin: 0; padding: 0; width: 100%; height: 100%; font-size: 0; }
      </style>
   </head>

   <body>
      <canvas id = "renderCanvas"></canvas>
      <script type = "text/javascript">
         var canvas = document.getElementById("renderCanvas");
         var engine = new BABYLON.Engine(canvas, true);
         var createScene  = function() {
            var scene = new BABYLON.Scene(engine);
            scene.clearColor = new BABYLON.Color3(0.8, 0.8, 0.8);
            
            var camera = new BABYLON.ArcRotateCamera("Camera", -Math.PI / 6, 1.3, 40, new BABYLON.Vector3(0, -3, 0), scene);
            
            var light = new BABYLON.HemisphericLight("hemi", new BABYLON.Vector3(0, 1, 0), scene);

            var mat = new BABYLON.StandardMaterial("mat", scene);
            mat.diffuseColor = new BABYLON.Color3(0.1, .5, 0);
            mat.specularColor = new BABYLON.Color3(0, 0, 0);
            mat.wireframe = true;

            var meshcylinder = BABYLON.MeshBuilder.CreateCylinder("meshcylinder", {
               height: 3,
               diameter: 35,
               tessellation: 52
            }, scene);

            meshcylinder.material = mat;
            meshcylinder.position = new BABYLON.Vector3(0, 0, 0);

            scene.activeCamera.attachControl(canvas);
            return scene;
         };
         
         var scene = createScene();
         engine.runRenderLoop(function() {
            scene.render();
         });
      </script>
   </body>
</html>

输出

上面的代码行生成以下输出 -

现在，将在一个演示中一起使用使用网格生成器创建的许多形状。下面的演示链接中涵盖的形状将在后续部分中列出。

BabylonJS – 网格交点和点

游戏中的网格相交非常重要，因为您知道游戏中两个对象相交时需要做什么。下面的演示中对网格相交时需要捕获的事件解释了相同的概念。

在下面给出的演示中，我们涵盖了以下两个概念 -

相交网格
交点

<!doctype html>
<html>
   <head>
      <meta charset = "utf-8">
      <title>BabylonJs - Basic Element-Creating Scene</title>
      <script src = "babylon.js"></script>
      <style>
         canvas {width: 100%; height: 100%;}
      </style>
   </head>

   <body>
      <canvas id = "renderCanvas"></canvas>
      <script type = "text/javascript">
         var canvas = document.getElementById("renderCanvas");
         var engine = new BABYLON.Engine(canvas, true);
         
         var createScene  = function() {
            var scene = new BABYLON.Scene(engine);
            scene.clearColor = new BABYLON.Color3(1, 1, 1);
            
            var camera = new BABYLON.ArcRotateCamera("ArcRotateCamera", 1, 0.8, 20, new BABYLON.Vector3(0, 0, 0), scene);
            camera.attachControl(canvas, true);

            var matcone = new BABYLON.StandardMaterial("mat1", scene);
            matcone.alpha = 1.0;
            matcone.diffuseColor = new BABYLON.Color3(0, 0, 0);
            matcone.wireframe = true;

            var cone = BABYLON.MeshBuilder.CreateCylinder("cone", {height : 10, diameterTop: 10,diameterBottom:10, tessellation: 5}, scene);
            cone.position= new BABYLON.Vector3(12,1,0);
            cone.material = matcone;	

            var balloon1 = BABYLON.Mesh.CreateSphere("balloon1",5, 1.0, scene);
            var balloon2 = BABYLON.Mesh.CreateSphere("balloon2", 5, 1.0, scene);
            var balloon3 = BABYLON.Mesh.CreateSphere("balloon3", 5, 1.0, scene);
            
            balloon1.material = new BABYLON.StandardMaterial("matBallon", scene);
            balloon2.material = new BABYLON.StandardMaterial("matBallon", scene);
            balloon3.material = new BABYLON.StandardMaterial("matBallon", scene);

            balloon1.position = new BABYLON.Vector3(4, 2, 0);
            balloon2.position = new BABYLON.Vector3(5, 1, 0);
            balloon3.position = new BABYLON.Vector3(7, 0, 0);

            var pointToIntersect = new BABYLON.Vector3(10, 0, 0);
            var a = 0.01;
            
            scene.registerBeforeRender(function () {
               if (balloon1.intersectsMesh(cone, false)) {
                  balloon1.material.emissiveColor = new BABYLON.Color3(1, 0, 0);
               } else {
                  balloon1.material.emissiveColor = new BABYLON.Color3(0, 1, 0);
               }

               if (balloon2.intersectsMesh(cone, false)) {
                  balloon2.material.emissiveColor = new BABYLON.Color3(1, 0, 0);
               } else {
                  balloon2.material.emissiveColor = new BABYLON.Color3(0, 1, 0);
               }

               if (balloon3.intersectsMesh(cone, false)) {
                  balloon3.material.emissiveColor = new BABYLON.Color3(1, 0, 0);
               } else {
                  balloon3.material.emissiveColor = new BABYLON.Color3(0, 1, 0);
               }

               if (balloon3.intersectsPoint(pointToIntersect)) {
                  balloon3.material.emissiveColor = new BABYLON.Color3(0, 0, 0);
               }

               a += 0.01;
               balloon1.position.x += Math.cos(a) / 10;
               balloon2.position.x += Math.cos(a) / 10;
               balloon3.position.x += Math.cos(a) / 10;
            });
            return scene;
         };
         var scene = createScene();
         engine.runRenderLoop(function() {
            scene.render();
         });
      </script>
   </body>
</html>

输出

上面的代码生成以下输出 -

解释

通过上面的代码，我们创建了一个线框为 true 的圆柱体。我们创建了 3 个球体。球体的原始颜色是绿色。

在scene.registerBeforeRender函数中，我们将根据与网格（此处为圆柱体）的交集来更改球体的颜色。

考虑registerBeforeRender中的以下代码-

if (balloon1.intersectsMesh(cone, false)) {
   balloon1.material.emissiveColor = new BABYLON.Color3(1, 0, 0);
} else {
   balloon1.material.emissiveColor = new BABYLON.Color3(0, 1, 0);
}

intersectsMesh如果与传递给它的参数中给定的网格相交，则给出 true 或 false。

例如，

balloon1.intersectsMesh(cone, false); //cone refers to the cylinder mesh here.

与圆柱体相交的球体颜色变为红色；否则，它是绿色的。

以下代码用于相交点 -

var pointToIntersect = new BABYLON.Vector3(10, 0, 0);
if (balloon3.intersectsPoint(pointToIntersect)) {
   balloon3.material.emissiveColor = new BABYLON.Color3(0, 0, 0);
}

这里，pointtoIntersect变量是位置向量，在 x 轴上为 10。如果球体穿过交点，球体的颜色将变为黑色。

BabylonJS – 网格拾取碰撞

选择碰撞实际上会为您提供坐标，您可以将网格物体放置在该位置。对象是通过鼠标拾取的，您只需将鼠标单击的位置放置即可。考虑您需要将网格（对象）放置在用户单击鼠标的位置；因此，在拾取碰撞的帮助下，它可以帮助您获得单击位置的坐标。

演示

<!doctype html>
<html>
   <head>
      <meta charset = "utf-8">
      <title>BabylonJs - Basic Element-Creating Scene</title>
      <script src = "babylon.js"></script>
      <style>
         canvas {width: 100%; height: 100%;}
      </style>
   </head>
   
   <body>
      <canvas id = "renderCanvas"></canvas>
      <script type = "text/javascript">
         var canvas = document.getElementById("renderCanvas");
         var engine = new BABYLON.Engine(canvas, true);
         var createScene  = function() {
            var scene = new BABYLON.Scene(engine);
            scene.clearColor = new BABYLON.Color3(1, 1, 1);

            // setup environment
            var light0 = new BABYLON.PointLight("Omni", new BABYLON.Vector3(0, 10, 20), scene);
            var freeCamera = new BABYLON.FreeCamera("FreeCamera", new BABYLON.Vector3(0, 0, -30), scene);

            var balloon1 = BABYLON.Mesh.CreateSphere("balloon1",5, 1.0, scene);
            var balloon2 = BABYLON.Mesh.CreateSphere("balloon2", 5, 1.0, scene);
            balloon1.material = new BABYLON.StandardMaterial("matBallon", scene);
            balloon2.material = new BABYLON.StandardMaterial("matBallon", scene);

            balloon1.position = new BABYLON.Vector3(0, 0, -0.1);
            balloon2.position = new BABYLON.Vector3(0, 0, -0.1);
            balloon1.material.emissiveColor = new BABYLON.Color3(1, 0, 0);
            balloon2.material.emissiveColor = new BABYLON.Color3(0, 0, 1);

            //Wall
            var wall = BABYLON.Mesh.CreatePlane("wall", 30.0, scene);
            wall.material = new BABYLON.StandardMaterial("wallMat", scene);
            wall.material.emissiveColor = new BABYLON.Color3(0.5, 1, 0.5);

            //When pointer down event is raised

            scene.onPointerDown = function (evt, pickResult) {
               // if the click hits the ground object, we change the impact position
               if (pickResult.hit) {
                  var dateValue = new Date();
                  var secondNumber = dateValue.getSeconds();
                  if (secondNumber % 2 == 0) {
                  balloon1.position.x = pickResult.pickedPoint.x;
                  balloon1.position.y = pickResult.pickedPoint.y;
                  } else {
                     balloon2.position.x = pickResult.pickedPoint.x;
                     balloon2.position.y = pickResult.pickedPoint.y;
                  }
               }
            };
            return scene;
         };
         var scene = createScene();
         engine.runRenderLoop(function() {
            scene.render();
         });
      </script>
   </body>
</html>

输出

解释

在上面的示例中，我们使用了一个平面和 2 个球体。要生成此输出，请使用以下代码 -

scene.onPointerDown = function (evt, pickResult) {
   // if the click hits the ground object, we change the impact position
   if (pickResult.hit) {
      var dateValue = new Date();
      var secondNumber = dateValue.getSeconds();
      if (secondNumber % 2 == 0) {
      balloon1.position.x = pickResult.pickedPoint.x;
      balloon1.position.y = pickResult.pickedPoint.y;
      } else {
         balloon2.position.x = pickResult.pickedPoint.x;
         balloon2.position.y = pickResult.pickedPoint.y;
      }
   }
};

事件scene.onPointerDown为您提供协调的 -x、y 和 z，在我们的示例中为pickResult。

如果您单击地面网格物体，它会将 pickResult.hit 设为 true。我们考虑奇数/偶数秒并更改球体的位置以选取结果 z 和 y 坐标，如上所示。位置更改后，球体将放置在您单击并放置鼠标的位置。您可以尝试上面的演示。

BabylonJS – 光线投射

光线投射就像太阳光线，用于检查场景中的碰撞和交叉。

句法

var ray = new BABYLON.Ray(origin, direction, length);

参数

考虑光线投射的以下参数 -

原点- 光线开始的地方。
方向- 射线方向计算如下 -

var forward = new BABYLON.Vector3(0,0,1);		
forward = vecToLocal(forward, box);
var direction = forward.subtract(origin);

然后，为了获得方向，我们从原点（即盒子位置）中减去它 -

长度- 射线的长度。

演示

<!doctype html>
<html>
   <head>
      <meta charset = "utf-8">
      <title>BabylonJs - Basic Element-Creating Scene</title>
      <script src = "babylon.js"></script>
      <style>
         canvas {width: 100%; height: 100%;}
      </style>
   </head>

   <body>
      <canvas id = "renderCanvas"></canvas>
      <script type = "text/javascript">
         var canvas = document.getElementById("renderCanvas");
         var engine = new BABYLON.Engine(canvas, true);
         
         var createScene  = function() {
            var scene = new BABYLON.Scene(engine);

            var light = new BABYLON.PointLight("Omni", new BABYLON.Vector3(0, 100, 100), scene);
            
            var camera = new BABYLON.ArcRotateCamera("Camera", 0, 0.8, 100, new BABYLON.Vector3.Zero(), scene);
            camera.attachControl(canvas, true);

            var ground = BABYLON.Mesh.CreateGround("ground", 500, 500, 10, scene);

            var box = BABYLON.Mesh.CreateBox("box", 4.0, scene);
            box.position.y = 2;
            box.scaling.z = 2;
           
            var matBox = new BABYLON.StandardMaterial("matBox", scene);
            matBox.diffuseColor = new BABYLON.Color3(0.8, 0.1, 0.5);
            box.material = matBox;
            box.isPickable = false; 

            var box2 = BABYLON.Mesh.CreateBox("box2", 8.0, scene);
            box2.position = new BABYLON.Vector3(-20, 4, 0); 
            
            var matBox2 = new BABYLON.StandardMaterial("matBox2", scene);
            matBox2.diffuseColor = new BABYLON.Color3(1, 0, 0);
            box2.material = matBox2;

            var box3 = BABYLON.Mesh.CreateBox("box3", 8.0, scene);
            box3.position = new BABYLON.Vector3(20, 4, 0); 
            
            var matBox3 = new BABYLON.StandardMaterial("matBox3", scene);
            matBox3.diffuseColor = new BABYLON.Color3(1, 0, 0);
            box3.material = matBox3;

            var box4 = BABYLON.Mesh.CreateBox("box4", 8.0, scene);
            box4.position = new BABYLON.Vector3(0, 0, 20); 
            
            var matBox4 = new BABYLON.StandardMaterial("matBox4", scene);
            matBox4.diffuseColor = new BABYLON.Color3(0, 1, 0);
            box4.material = matBox4;

            var box5 = BABYLON.Mesh.CreateBox("box5", 8.0, scene);
            box5.position = new BABYLON.Vector3(0, 0, -20); 
            
            var matBox5 = new BABYLON.StandardMaterial("matBox5", scene);
            matBox5.diffuseColor = new BABYLON.Color3(0, 1, 0);
            box5.material = matBox5;

            function mousemovef() {
               var pickResult = scene.pick(scene.pointerX, scene.pointerY);

               if (pickResult.hit) {
                  var diffX = pickResult.pickedPoint.x - box.position.x;
                  var diffY = pickResult.pickedPoint.z - box.position.z;
                  box.rotation.y = Math.atan2(diffX,diffY);			
               }	
            }

            scene.onPointerMove = function () {
               mousemovef();
            };

            function vecToLocal(vector, mesh) {
               var m = mesh.getWorldMatrix();
               var v = BABYLON.Vector3.TransformCoordinates(vector, m);
               return v;		
            }   

            scene.registerBeforeRender(function () {
               var origin = box.position;

               var forward = new BABYLON.Vector3(0,0,1);		
               forward = vecToLocal(forward, box);

               var direction = forward.subtract(origin);
               direction = BABYLON.Vector3.Normalize(direction);

               var length = 100;

               var ray = new BABYLON.Ray(origin, direction, length);
               // ray.show(scene, new BABYLON.Color3(1, 1, 0.1));

               var hit = scene.pickWithRay(ray);

               if (hit.pickedMesh) {
                  hit.pickedMesh.scaling.y  += 0.01;
               }
            });		
            return scene;
         };
         var scene = createScene();
         engine.runRenderLoop(function() {
            scene.render();
         });
      </script>
   </body>
</html>

输出

上面的代码行生成以下输出 -

解释

中心有一个主盒子，充当光线投射。当它指向任何一个盒子时，盒子的大小就会增加。事实证明，这个概念在玩游戏时非常有用，可以了解哪个其他物体正在接触并可以采取必要的行动。

添加box.isPickable = false; 这样就不考虑中心的主框了。如果您不希望任何物体包含在光线中进行接触，请添加box.isPickable = false; 到它。

以下代码添加了由射线拾取的框的缩放。

scene.registerBeforeRender(function () {
   var origin = box.position;	
   var forward = new BABYLON.Vector3(0,0,1);		
   forward = vecToLocal(forward, box);

   var direction = forward.subtract(origin);
   direction = BABYLON.Vector3.Normalize(direction);

   var length = 100;

   var ray = new BABYLON.Ray(origin, direction, length);

   var hit = scene.pickWithRay(ray);

   if (hit.pickedMesh) {
      hit.pickedMesh.scaling.y  += 0.01;
   }
});

var ray = new BABYLON.Ray(原点、方向、长度); 创建一条射线，并将主框位置作为原点。

射线方向计算如下 -

var forward = new BABYLON.Vector3(0,0,1);		
forward = vecToLocal(forward, box);
var direction = forward.subtract(origin);

然后，为了获得方向，我们从原点（即盒子位置）中减去它。函数vecToLocal旨在通过将向量乘以网格矩阵来从网格角度转换位置。

我们使用var hit = scene.pickWithRay(ray);从射线中获取命中点

它给出了光线与网格重合的位置。

缩放应用于通过执行以下代码行拾取的网格 -

if (hit.pickedMesh) {
   hit.pickedMesh.scaling.y  += 0.01;
}

在浏览器中尝试上面的示例以查看输出。

带有谓词函数的光线投射

现在让我们看看带有谓词函数的 raycast 是如何工作的以及 rayhelper 显示的方向。

演示

<!doctype html>
<html>
   <head>
      <meta charset = "utf-8">
      <title>BabylonJs - Basic Element-Creating Scene</title>
      <script src = "babylon.js"></script>
      <style>
         canvas {width: 100%; height: 100%;}
      </style>
   </head>
   
   <body>
      <canvas id = "renderCanvas"></canvas>
      <script type = "text/javascript">
         var canvas = document.getElementById("renderCanvas");
         var engine = new BABYLON.Engine(canvas, true);
         var createScene  = function() {
            var scene = new BABYLON.Scene(engine);

            var light = new BABYLON.PointLight("Omni", new BABYLON.Vector3(0, 100, 100), scene);
            var camera = new BABYLON.ArcRotateCamera("Camera", 0, 0.8, 100, new BABYLON.Vector3.Zero(), scene);
            camera.attachControl(canvas, true);

            var ground = BABYLON.Mesh.CreateGround("ground", 500, 500, 10, scene);

            var box = BABYLON.Mesh.CreateBox("box", 4.0, scene);
            box.position.y = 2;
            box.scaling.z = 2;
            var matBox = new BABYLON.StandardMaterial("matBox", scene);
            matBox.diffuseColor = new BABYLON.Color3(0.8, 0.1, 0.5);
            box.material = matBox;
            box.isPickable = false; 

            var box2 = BABYLON.Mesh.CreateBox("box2", 8.0, scene);
            box2.position = new BABYLON.Vector3(-20, 4, 0); 
            var matBox2 = new BABYLON.StandardMaterial("matBox2", scene);
            matBox2.diffuseColor = new BABYLON.Color3(1, 0, 0);
            box2.material = matBox2;

            var box3 = BABYLON.Mesh.CreateBox("box3", 8.0, scene);
            box3.position = new BABYLON.Vector3(20, 4, 0); 
            var matBox3 = new BABYLON.StandardMaterial("matBox3", scene);
            matBox3.diffuseColor = new BABYLON.Color3(1, 0, 0);
            box3.material = matBox3;

            var box4 = BABYLON.Mesh.CreateBox("box4", 8.0, scene);
            box4.position = new BABYLON.Vector3(0, 0, 20); 
            var matBox4 = new BABYLON.StandardMaterial("matBox4", scene);
            matBox4.diffuseColor = new BABYLON.Color3(0, 1, 0);
            box4.material = matBox4;

            var box5 = BABYLON.Mesh.CreateBox("box5", 8.0, scene);
            box5.position = new BABYLON.Vector3(0, 0, -20); 
            var matBox5 = new BABYLON.StandardMaterial("matBox5", scene);
            matBox5.diffuseColor = new BABYLON.Color3(0, 1, 0);
            box5.material = matBox5;

            //ray showing the direction
            var ray = new BABYLON.Ray();
            var rayHelper = new BABYLON.RayHelper(ray);

            var localMeshDirection = new BABYLON.Vector3(0, 0, -1);
            var localMeshOrigin = new BABYLON.Vector3(0, 0, -.4);
            var length = 10;

            rayHelper.attachToMesh(box, localMeshDirection, localMeshOrigin, length);
            rayHelper.show(scene);

            function mousemovef() {
               var pickResult = scene.pick(scene.pointerX, scene.pointerY);

               if (pickResult.hit) {
                  var diffX = pickResult.pickedPoint.x - box.position.x;
                  var diffY = pickResult.pickedPoint.z - box.position.z;
                  box.rotation.y = Math.atan2(diffX,diffY);			
               }	
            }

            scene.onPointerMove = function () {
               mousemovef();
            };

            function vecToLocal(vector, mesh) {
               var m = mesh.getWorldMatrix();
               var v = BABYLON.Vector3.TransformCoordinates(vector, m);
               return v;		
            }   

            scene.registerBeforeRender(function () {
               var origin = box.position;
               function predicate(mesh) {
                  if (mesh == box2 || mesh == box || mesh == box5) {
                     return false;
                  }
                  return true;
               }
               
               var forward = new BABYLON.Vector3(0,0,1);		
               forward = vecToLocal(forward, box);

               var direction = forward.subtract(origin);
               direction = BABYLON.Vector3.Normalize(direction);

               var length = 100;

               var ray = new BABYLON.Ray(origin, direction, length);
               // ray.show(scene, new BABYLON.Color3(1, 1, 0.1));

               var hit = scene.pickWithRay(ray, predicate);
               if (hit.pickedMesh) {
                  hit.pickedMesh.scaling.y  += 0.01;
               }
            });		
            return scene;
         };
         var scene = createScene();
         engine.runRenderLoop(function() {
            scene.render();
         });
      </script>
   </body>
</html>

输出

上面的代码行生成以下输出 -

解释

带有谓词函数的光线投射有助于选择我们想要的网格。如果我们不想选择网格，我们可以忽略它。

function predicate(mesh) {
   if (mesh == box2 || mesh == box || mesh == box5) {
      return false;
   }
   return true;
}

上述函数给出了射线选择的网格。如果选择的网格是box2、box、box5，则返回false；否则，为真。

您可以尝试上面的示例。

BabylonJS – 网格阴影

阴影根据光线落在所创建的网格上的方式进行渲染。它们在使输出在 3D 世界中看起来更真实方面发挥着重要作用。

现在让我们学习如何使用babylonjs 创建阴影。

句法

var shadowGenerator00 = new BABYLON.ShadowGenerator(shadowsize, light);

参数

考虑以下与网格阴影相关的参数 -

Shadowsize - 阴影的大小。
光- 场景中使用的光。

演示

<!doctype html>
<html>
   <head>
      <meta charset = "utf-8">
      <title>BabylonJs - Basic Element-Creating Scene</title>
      <script src = "babylon.js"></script>
      <style>
         canvas {width: 100%; height: 100%;}
      </style>
   </head>

   <body>
      <canvas id = "renderCanvas"></canvas>
      <script type = "text/javascript">
         var canvas = document.getElementById("renderCanvas");
         var engine = new BABYLON.Engine(canvas, true);
         
         var createScene  = function() {
            var scene = new BABYLON.Scene(engine);
            scene.clearColor = new BABYLON.Color3(1, 1, 1);	
            var camera = new BABYLON.ArcRotateCamera("ArcRotateCamera", 1, 0.8, 20, new BABYLON.Vector3(0, 0, 0), scene);
            camera.attachControl(canvas, true);
            // light1
            var light = new BABYLON.DirectionalLight("dir01", new BABYLON.Vector3(-1, -2, -1), scene);
            light.position = new BABYLON.Vector3(20, 40, 20);

            var ground01 = BABYLON.Mesh.CreateGround("Spotlight Hard Shadows", 24, 60, 1, scene, false);
            var groundMaterial = new BABYLON.StandardMaterial("ground", scene);
            groundMaterial.diffuseTexture = new BABYLON.Texture("images/gr1.jpg", scene);
            groundMaterial.specularColor = new BABYLON.Color3(0, 0, 0);
            groundMaterial.emissiveColor = new BABYLON.Color3(0.2, 0.2, 0.2);

            ground01.material = groundMaterial;
            ground01.receiveShadows = true;
            ground01.position.x = -5;

            var box = BABYLON.Mesh.CreateBox("box", 3.0, scene);
            box.position.x = -5;
            box.position.y = 5;
            var shadowGenerator00 = new BABYLON.ShadowGenerator(512, light);
            shadowGenerator00.getShadowMap().renderList.push(box);
            //shadowGenerator00.usePoissonSampling = true;
            //shadowGenerator00.useExponentialShadowMap = true;
            shadowGenerator00.useBlurExponentialShadowMap = true;
            shadowGenerator00.bias = 0.01;
            scene.registerBeforeRender(function() {
               box.rotation.x += 0.01;
               box.rotation.x += 0.01;
            });
            return scene;
         };
         var scene = createScene();
         engine.runRenderLoop(function() {
            scene.render();
         });
      </script>
   </body>
</html>

输出

上面的代码行生成以下输出 -

解释

要创建阴影，您需要创建阴影生成器。考虑如下所示的示例。

var shadowGenerator00 = new BABYLON.ShadowGenerator(512, light);

要定义需要阴影的网格，您需要将其添加到上面的生成器中。

shadowGenerator00.getShadowMap().renderList.push(box);

现在，我们创建了一个地面并在其顶部创建了一个盒子。我们希望盒子的影子落在地上。为此，我们需要确保地面被标记为接收阴影，具体操作如下 -

ground01.receiveShadows = true;

有一些可用于阴影的过滤器，如下所示 -

shadowGenerator.usePoissonSampling = true; - Called Poisson sampling 
shadowGenerator.useExponentialShadowMap = true; - Exponential Shadow Map
shadowGenerator.useBlurExponentialShadowMap= true;  - Blur Exponential Shadow Map

在我们的演示中，我们使用了shadowGenerator00.useBlurExponentialShadowMap = true; 您可以尝试其他方法并查看输出结果。

在这里，我们使用了名为 gr1.jpg 的图像。图像存储在本地的 images/ 文件夹中。您可以下载您选择的任何图像并在演示链接中使用。

BabylonJS – 网格上的高级纹理

在本节中，我们将了解网格上的高级纹理。不同的纹理如下所示 -

让我们向网格应用一些复杂的纹理 - 镜子、凹凸、视频和折射。

先生。	网格及描述
1	网格高光层高光图层用于突出显示场景中的网格。您可以为其指定颜色，并将颜色应用于网格的边框。如果您想在游戏中突出显示，可以使用网格突出显示层。
2	变形网格变形通过某种过渡方式将一个对象的形状更改为另一个对象的形状。我们已经看到了形状的可更新参数；否则该参数设置为 false。对于变形，将其设置为 true 并更新网格以更改形状。
3	网格动作动作用于向网格添加交互。当您单击网格或网格相交或碰撞时，事件将被激活。
4	网格资产管理器使用assestsmanager类，您可以在场景中加载网格、图像和二进制文件。
5	导入网格我们将学习使用导入网格。
6	网格变形目标我们已经看到了线、带、多边形等的变形。现在，我们将在这个演示中看到球体和盒子的变形。通过变形目标，球体的形状发生了变化，如下面的演示所示。
7	网格实例如果您想在场景中绘制相同的网格，请使用实例。
8	网格 LOD 和实例 LOD 代表距离线。此功能允许您根据观察者的距离指定网格。随着观察者到对象的距离增加，网格的细节级别会使用 LOD 清晰显示。
9	网格体积光散射后处理此过程会散射光，如下面给出的输出所示。在浏览器中进行相同的测试，您将看到光线如何通过网格散射。
10	网格边缘渲染器 EdgesRendering 用于在网格周围绘制边缘，如上面的输出所示。
11	网格混合模式您可以通过修改材质的 alphamode 来创建混合模式。
12	网格实体粒子 SolidParticle 系统在网格上更新。我们在网格上看到的所有属性都可以用于固体粒子。
13	网格面数据 Facet数据占用大量内存，默认情况下不启用此功能。为了启用它，我们需要根据需要创建一个网格并向其更新面数据。