前言

前段時間想要做一個web端的圖形化積木式編程（類似少兒編程）的案例，網上沖浪了一圈又一圈，終于技術選型好，然后代碼一頓敲，終于出來了一個雛形。

TIPS：該案例設計主要參考iRobot Coding,只用做學習用途，侵刪。

https://code.irobot.com/#/

最終實現效果

最終實現效果

本文實現效果

• 實現碰撞效果

  
  
  實現碰撞效果

完整代碼

• 實現碰撞效果

<template>
  <div style="height: 100%;width: 100%;">
    <div>
      <canvas id="renderCanvas"></canvas>
    </div>
  </div>
</template>

<script>
import * as BABYLON from 'babylonjs';
import * as BABYLON_MATERAIAL from "babylonjs-materials"
import ammo from "ammo.js";
import utils from "./utils";

//全局變量
var scene = null //場景實例
var engine = null //3d引擎實例
var camera = null //攝像機實例
var plane = null //綠地
var ground = null //網格
var skybox = null //天空盒
var car = null //小車
var cubeParent = null //方塊組
var startingPoint = new BABYLON.Vector3(0, 0, 0)//當前點擊位置

// 質量 、摩擦系數、反彈系數
const bodyMass = 0.5, bodyFriction = 0.5, bodyRestitution = 0.9;
const groundFriction = 0.8, groundRestitution = 0.5;

async function loadScene() {
  //場景初始化，可看文章一
  scene = initScene()
  //加載網絡模型，可看文章二
  await initRobot()

  //可看文章三，監聽拖動事件，實現點擊拖動模型
  dragListening()

  //本文內容
  // 1、初始化重力碰撞系統
  await initAmmo()
  // 2、將地面和小車加入碰撞體
  addPhysicEffect()
  //3、加入碰撞體方塊
  initCubes()

  //開啟debug窗口
  // scene.debugLayer.show()

}

async function initAmmo() {
  const Ammo = await ammo();
  console.log("Ammo", Ammo)
  //啟用y方向重力
  scene.enablePhysics(new BABYLON.Vector3(0, -10, 0), new BABYLON.AmmoJSPlugin(true, Ammo));

  scene.onReadyObservable.add(function () {
    console.log(scene.getPhysicsEngine()._physicsPlugin.bjsAMMO.btDefaultCollisionConfiguration());
    console.log(scene.getPhysicsEngine()._physicsPlugin._collisionConfiguration);
    console.log(scene.getPhysicsEngine()._physicsPlugin._dispatcher);
    console.log(scene.getPhysicsEngine()._physicsPlugin._solver);
    console.log(scene.getPhysicsEngine()._physicsPlugin.world);
  });
}

function addPhysicEffect() {
  //地面啟用碰撞體
  plane.physicsImpostor = new BABYLON.PhysicsImpostor(plane, BABYLON.PhysicsImpostor.BoxImpostor, {
    mass: 0,
    restitution: groundRestitution,
    friction: groundFriction
  }, scene);

  //小車啟用碰撞體
  var robotBody = utils.getMeshFromMeshs(car, "Glass_Plane.006")
  console.log('robotBody', robotBody)

  var robotSize = utils.getMeshSize(robotBody)
  var robotScale = 50
  const robotScalingFactor = robotScale / 10;
  var physicsRoot = makePhysicsObjects(car, scene, robotScalingFactor, robotSize)
  //小車實例
  car = physicsRoot

}


function makePhysicsObjects(newMeshes, scene, scaling, size) {
  var physicsRoot = new BABYLON.Mesh("robot", scene);
  physicsRoot.position.y -= 2
  newMeshes.forEach((m) => {
    if (m.parent == null) {
      physicsRoot.addChild(m)
    }
  })

  // 將所有碰撞體加入physics impostor
  physicsRoot.getChildMeshes().forEach((m) => {
    m.scaling.x = Math.abs(m.scaling.x)
    m.scaling.y = Math.abs(m.scaling.y)
    m.scaling.z = Math.abs(m.scaling.z)
    // console.log("m.name",m.name)
    m.physicsImpostor = new BABYLON.PhysicsImpostor(m, BABYLON.PhysicsImpostor.BoxImpostor, {mass: 0.1}, scene);
  })

  // 縮放根對象并將其變成physics impostor
  physicsRoot.scaling.scaleInPlace(scaling)

  physicsRoot.physicsImpostor = new BABYLON.PhysicsImpostor(physicsRoot, BABYLON.PhysicsImpostor.NoImpostor, {
    mass: bodyMass,
    friction: bodyFriction,
    restitution: bodyRestitution
  }, scene);

  //轉為碰撞體后，其y軸會偏移，偏移比例根據實際調整
  const impostorOffset = -(size.y) / 1.1
  physicsRoot.physicsImpostor.setDeltaPosition(new BABYLON.Vector3(0, impostorOffset, 0));
  physicsRoot.position.subtractInPlace(new BABYLON.Vector3(0, -impostorOffset, 0));
  return physicsRoot
}

function initCubes() {
  var scale = 1
  const scalingFactor = scale / 10;
  cubeParent = new BABYLON.TransformNode("cubes");
  const cubeHeight = 80 * scalingFactor
  var cube = createBasicRoundedBox(scene, "cube", cubeHeight)

  cube.position._y += cubeHeight / 2
  cube.position._x -= 100
  cube.material = new BABYLON.StandardMaterial("amaterial", scene);
  cube.material.diffuseColor = new BABYLON.Color3(16 / 255.0, 156 / 255.0, 73 / 255.0);
  cubeParent[0] = cube

  var cube2 = createBasicRoundedBox(scene, "cube2", cubeHeight)
  cube2.position._y += cubeHeight / 2
  cube2.position._x -= 100
  cube2.position._z += cubeHeight * 2
  cube2.material = new BABYLON.StandardMaterial("amaterial", scene);
  cube2.material.diffuseColor = new BABYLON.Color3(48 / 255.0, 102 / 255.0, 150 / 255.0);
  cubeParent[1] = cube2

  var cube3 = createBasicRoundedBox(scene, "cube3", cubeHeight)
  cube3.position._y += cubeHeight / 2
  cube3.position._x -= 100
  cube3.position._z -= cubeHeight * 2
  cube3.material = new BABYLON.StandardMaterial("amaterial", scene);
  cube3.material.diffuseColor = new BABYLON.Color3(199 / 255.0, 88 / 255.0, 93 / 255.0);
  cubeParent[2] = cube3

  //對象事件監聽
  let actionManager = new BABYLON.ActionManager(scene);
  cube.actionManager = actionManager;
  cube2.actionManager = actionManager;
  cube3.actionManager = actionManager;

  // 方塊鼠標hover高亮
  var hl = new BABYLON.HighlightLayer("hl1", scene);
  actionManager.registerAction(new BABYLON.ExecuteCodeAction(BABYLON.ActionManager.OnPointerOverTrigger, function (evn) {
    var hover_cube = evn.meshUnderPointer.id
    if (hover_cube == cube.name) {
      hl.addMesh(cube, BABYLON.Color3.White());
    } else if (hover_cube == cube2.name) {
      hl.addMesh(cube2, BABYLON.Color3.White());
    } else if (hover_cube == cube3.name) {
      hl.addMesh(cube3, BABYLON.Color3.White());
    }


  }));
  //方塊鼠標hover離開取消高亮
  actionManager.registerAction(new BABYLON.ExecuteCodeAction(BABYLON.ActionManager.OnPointerOutTrigger, function (evn) {
    var hover_cube = evn.meshUnderPointer.id
    if (hover_cube == cube.name) {
      hl.removeMesh(cube);
    } else if (hover_cube == cube2.name) {
      hl.removeMesh(cube2);
    } else if (hover_cube == cube3.name) {
      hl.removeMesh(cube3);
    }
  }));

  scene.freezeMaterials();
}

//創建帶碰撞體的方塊
function createBasicRoundedBox(scene, name, size, mass = 0.25, restitution = 0.5, friction = 0.5) {
  const boxSide = size;
  const sphereSide = boxSide * 3.1 / 2;
  const sphere = BABYLON.MeshBuilder.CreateSphere('sphere', {diameter: sphereSide, segments: 16}, scene);
  const box = BABYLON.Mesh.CreateBox('box', boxSide, scene);
  const intersection = BABYLON.CSG.FromMesh(box).intersect(BABYLON.CSG.FromMesh(sphere));
  sphere.dispose();
  box.dispose();
  const roundedBox = intersection.toMesh(
      name,
      new BABYLON.StandardMaterial('roundedBoxMaterial', scene),
      scene
  );
  roundedBox.draggable = true;
  roundedBox.physicsImpostor = new BABYLON.PhysicsImpostor(
      roundedBox,
      BABYLON.PhysicsImpostor.BoxImpostor,
      {mass: mass, restitution: restitution, friction: friction}
  );
  roundedBox.material.freeze();
  roundedBox.material.specularColor = new BABYLON.Color3(0, 0, 0);
  roundedBox.freezeWorldMatrix()
  return roundedBox;
}

//鼠標點擊拖動監聽
function dragListening() {
  // 物體拖拽事件
  var canvas = engine.getRenderingCanvas();

  var currentMesh;//當前點擊的模型網格

  //判斷當前點擊對象是否是地板
  var getGroundPosition = function () {
    var pickinfo = scene.pick(scene.pointerX, scene.pointerY, function (mesh) {
      return (mesh == ground || mesh == plane);
    });
    if (pickinfo.hit) {
      return pickinfo.pickedPoint;
    }
    return null;
  }

  //鼠標點下
  var onPointerDown = function (evt) {
    if (evt.button !== 0) {
      return;
    }
    //判斷當前是否點擊一個模型網格，如果是地板、天空盒等對象，則設置hit為false
    var pickInfo = scene.pick(scene.pointerX, scene.pointerY, function (mesh) {
      return (mesh !== ground && mesh !== plane && mesh !== skybox);
    });
    console.log("pickInfo", pickInfo)
    //如果hit為true，則不為地板、天空盒等對象
    if (pickInfo.hit) {
      currentMesh = pickInfo.pickedMesh;//獲取當前點擊對象
      if (currentMesh.parent == null) {
        console.log("no parent")//沒有父節點則就是car對象了
      } else if (currentMesh.parent.name == car.name) {
        //有父節點，證明現在點擊的是子對象，而移動需要移動整個小車對象，所以設置當前點擊mesh為父節點（即car對象）
        currentMesh = currentMesh.parent
      }
      console.log("currentMesh", currentMesh)
      //獲取當前移動時地板的坐標
      startingPoint = getGroundPosition(evt);
      //移動物體時，暫時屏蔽相機的移動控制
      if (startingPoint) { // we need to disconnect camera from canvas
        setTimeout(function () {
          camera.detachControl(canvas);
        }, 0);
      }
    }
  }

  //鼠標點擊著移動中
  var onPointerMove = function (evt) {
    if (!startingPoint) {
      return;
    }
    if (!currentMesh) {
      return;
    }
    //更新當前點擊的地板位置
    var current = getGroundPosition(evt);
    if (!current) {
      return;
    }
    //更新當前小車坐標位置為點擊的地板位置
    console.log('startingPoint', startingPoint)
    var diff = current.subtract(startingPoint);
    console.log('diff', diff)
    currentMesh.position.addInPlace(diff);
    console.log("currentMesh.name", currentMesh.name)
    //更新位置信息
    startingPoint = current;
  }

  //鼠標點擊后松開
  var onPointerUp = function () {
    //恢復相機移動控制
    if (startingPoint) {
      camera.attachControl(canvas, true);
      startingPoint = null;
      return;
    }
  }

  //canvas綁定監聽事件
  canvas.addEventListener("pointerdown", onPointerDown, false);
  canvas.addEventListener("pointerup", onPointerUp, false);
  canvas.addEventListener("pointermove", onPointerMove, false);
}


async function initRobot() {
  console.log('initRobot')
  //模型url路徑
  const url = "http://localhost:8088/static/model/"
  //模型名稱
  const modelName = "sportcar.babylon"
  var result = await BABYLON.SceneLoader.ImportMeshAsync(null, url, modelName, scene);
  var meshes = result.meshes
  console.log("meshes", meshes)
  car = meshes
}

function initScene() {
  //獲取到renderCanvas這個元素
  var canvas = document.getElementById("renderCanvas");
  //初始化引擎
  engine = new BABYLON.Engine(canvas, true);
  //初始化場景
  var scene = new BABYLON.Scene(engine);
  //注冊一個渲染循環來重復渲染場景
  engine.runRenderLoop(function () {
    scene.render();
  });
  //瀏覽器窗口變化時監聽
  window.addEventListener("resize", function () {
    engine.resize();
  });

  //相機初始化
  camera = new BABYLON.ArcRotateCamera("Camera", 0, 0, 5, new BABYLON.Vector3(0, 0, 10), scene);
  camera.setPosition(new BABYLON.Vector3(20, 200, 400));
  //相機角度限制
  camera.upperBetaLimit = 1.5;//最大z軸旋轉角度差不多45度俯瞰
  camera.lowerRadiusLimit = 50;//最小縮小比例
  camera.upperRadiusLimit = 1500;//最大放大比例
  //變焦速度
  camera.wheelPrecision = 1; //電腦滾輪速度 越小靈敏度越高
  camera.pinchPrecision = 20; //手機放大縮小速度 越小靈敏度越高
  scene.activeCamera.panningSensibility = 100;//右鍵平移靈敏度
  // 將相機和畫布關聯
  camera.attachControl(canvas, true);

  //燈光初始化
  var light = new BABYLON.HemisphericLight("light1", new BABYLON.Vector3(0, 10, 0), scene);
  //設置高光顏色
  light.specular = new BABYLON.Color3(0, 0, 0);
  //設置燈光強度
  light.intensity = 1

  // 綠地初始化
  var materialPlane = new BABYLON.StandardMaterial("texturePlane", scene);
  materialPlane.diffuseColor = new BABYLON.Color3(152 / 255.0, 209 / 255.0, 115 / 255.0)
  materialPlane.backFaceCulling = false;
  materialPlane.freeze()
  plane = BABYLON.MeshBuilder.CreateDisc("ground", {radius: 3000}, scene);
  plane.rotation.x = Math.PI / 2;
  plane.material = materialPlane;
  plane.position.y = -0.1;
  plane.freezeWorldMatrix()

  //網格地板初始化
  const groundSide = 144;
  ground = BABYLON.Mesh.CreateGround("ground", groundSide, groundSide, 1, scene, true);
  var groundMaterial = new BABYLON_MATERAIAL.GridMaterial("grid", scene);
  groundMaterial.mainColor = BABYLON.Color3.White();//底板顏色
  groundMaterial.alpha = 1;//透明度
  const gridLineGray = 0.95;
  groundMaterial.lineColor = new BABYLON.Color3(gridLineGray, gridLineGray, gridLineGray);
  groundMaterial.backFaceCulling = true; // 可看到背面
  //大網格間距
  groundMaterial.majorUnitFrequency = 16;
  //小網格間距
  groundMaterial.minorUnitVisibility = 0;
  const gridOffset = 8; // 網格偏移量
  groundMaterial.gridOffset = new BABYLON.Vector3(gridOffset, 0, gridOffset);
  groundMaterial.freeze(); // 凍結材質，優化渲染速度
  ground.material = groundMaterial
  ground.freezeWorldMatrix()

  //天空盒初始化
  var skyMaterial = new BABYLON_MATERAIAL.SkyMaterial("skyMaterial", scene);
  skyMaterial.inclination = 0
  skyMaterial.backFaceCulling = false;
  skybox = BABYLON.Mesh.CreateBox("skyBox", 5000.0, scene);
  skybox.material = skyMaterial;

  return scene
}


export default {
  name: "test",
  data() {
    return {}
  },
  async mounted() {
    //加載場景
    await loadScene()
  },
}
</script>

<style scoped>
#renderCanvas {
  width: 680px;
  height: 680px;
  touch-action: none;
  z-index: 10000;
  border-radius: 10px;
}
</style>

• utils.js - 公用方法封裝

var utils = {
    //meshs中根據名稱獲取mesh
    getMeshFromMeshs(newMeshes, name) {
        var mesh = null
        newMeshes.forEach(m => {
            if (m.name == name) {
                mesh = m
            }
        })
        return mesh
    },

    //獲取mesh的尺寸信息
    getMeshSize(checkmesh) {
        const sizes = checkmesh.getHierarchyBoundingVectors()
        const size = {
            x: (sizes.max.x - sizes.min.x),
            y: (sizes.max.y - sizes.min.y),
            z: (sizes.max.z - sizes.min.z)
        }
        return size
    },
}
export default utils;

代碼分解

本文要實現的功能:
1、引入Ammo.js物理引擎
2、將地面和小車加入碰撞體，測試小車和地面的碰撞效果
3、加入方塊碰撞體，測試小車和方塊的碰撞效果

0.NPM安裝Ammo.js物理引擎依賴

npm install kripken/ammo.js

1.初始化物理引擎

async function initAmmo() {
  const Ammo = await ammo();
  console.log("Ammo", Ammo)
  //啟用y方向重力
  scene.enablePhysics(new BABYLON.Vector3(0, -10, 0), new BABYLON.AmmoJSPlugin(true, Ammo));

  scene.onReadyObservable.add(function () {
    console.log(scene.getPhysicsEngine()._physicsPlugin.bjsAMMO.btDefaultCollisionConfiguration());
    console.log(scene.getPhysicsEngine()._physicsPlugin._collisionConfiguration);
    console.log(scene.getPhysicsEngine()._physicsPlugin._dispatcher);
    console.log(scene.getPhysicsEngine()._physicsPlugin._solver);
    console.log(scene.getPhysicsEngine()._physicsPlugin.world);
  });
}

2.地面和小車加入碰撞體

function addPhysicEffect() {
  //地面啟用碰撞體
  plane.physicsImpostor = new BABYLON.PhysicsImpostor(plane, BABYLON.PhysicsImpostor.BoxImpostor, {
    mass: 0,
    restitution: groundRestitution,
    friction: groundFriction
  }, scene);

  //小車啟用碰撞體
  var robotBody = utils.getMeshFromMeshs(car, "Glass_Plane.006")
  console.log('robotBody', robotBody)

  var robotSize = utils.getMeshSize(robotBody)
  var robotScale = 50
  const robotScalingFactor = robotScale / 10;
  var physicsRoot = makePhysicsObjects(car, scene, robotScalingFactor, robotSize)
  //小車實例
  car = physicsRoot
}

• 其中，小車初始化部分作小改動，不直接實例化，而是先存儲meshs的網格列表

async function initRobot() {
  console.log('initRobot')
  //模型url路徑
  const url = "http://localhost:8088/static/model/"
  //模型名稱
  const modelName = "sportcar.babylon"
  var result = await BABYLON.SceneLoader.ImportMeshAsync(null, url, modelName, scene);
  var meshes = result.meshes
  console.log("meshes", meshes)
  // 直接構造一個car的父節點，然后實例化
  // var parent = new BABYLON.Mesh("car", scene);
  // const scale = 10//縮放比例
  // for (var mesh of meshes) {
  //   mesh.scaling = new BABYLON.Vector3(scale, scale, scale)
  //   mesh.parent = parent
  // }
  // //將根節點設置為全局變量
  // car = parent
      
  //不直接實例化小車節點，car對象存儲meshes網格列表，在小車引入碰撞體后再實例化
  car = meshes
}

3.引入方塊碰撞體

• 為了方便看碰撞效果，引入方塊組
• 初始化方塊組，加入碰撞體和hover高亮

function initCubes() {
  var scale = 1
  const scalingFactor = scale / 10;
  cubeParent = new BABYLON.TransformNode("cubes");
  const cubeHeight = 80 * scalingFactor
  var cube = createBasicRoundedBox(scene, "cube", cubeHeight)

  cube.position._y += cubeHeight / 2
  cube.position._x -= 100
  cube.material = new BABYLON.StandardMaterial("amaterial", scene);
  cube.material.diffuseColor = new BABYLON.Color3(16 / 255.0, 156 / 255.0, 73 / 255.0);
  cubeParent[0] = cube

  var cube2 = createBasicRoundedBox(scene, "cube2", cubeHeight)
  cube2.position._y += cubeHeight / 2
  cube2.position._x -= 100
  cube2.position._z += cubeHeight * 2
  cube2.material = new BABYLON.StandardMaterial("amaterial", scene);
  cube2.material.diffuseColor = new BABYLON.Color3(48 / 255.0, 102 / 255.0, 150 / 255.0);
  cubeParent[1] = cube2

  var cube3 = createBasicRoundedBox(scene, "cube3", cubeHeight)
  cube3.position._y += cubeHeight / 2
  cube3.position._x -= 100
  cube3.position._z -= cubeHeight * 2
  cube3.material = new BABYLON.StandardMaterial("amaterial", scene);
  cube3.material.diffuseColor = new BABYLON.Color3(199 / 255.0, 88 / 255.0, 93 / 255.0);
  cubeParent[2] = cube3

  //對象事件監聽
  let actionManager = new BABYLON.ActionManager(scene);
  cube.actionManager = actionManager;
  cube2.actionManager = actionManager;
  cube3.actionManager = actionManager;

  // 方塊鼠標hover高亮
  var hl = new BABYLON.HighlightLayer("hl1", scene);
  actionManager.registerAction(new BABYLON.ExecuteCodeAction(BABYLON.ActionManager.OnPointerOverTrigger, function (evn) {
    var hover_cube = evn.meshUnderPointer.id
    if (hover_cube == cube.name) {
      hl.addMesh(cube, BABYLON.Color3.White());
    } else if (hover_cube == cube2.name) {
      hl.addMesh(cube2, BABYLON.Color3.White());
    } else if (hover_cube == cube3.name) {
      hl.addMesh(cube3, BABYLON.Color3.White());
    }


  }));
  //方塊鼠標hover離開取消高亮
  actionManager.registerAction(new BABYLON.ExecuteCodeAction(BABYLON.ActionManager.OnPointerOutTrigger, function (evn) {
    var hover_cube = evn.meshUnderPointer.id
    if (hover_cube == cube.name) {
      hl.removeMesh(cube);
    } else if (hover_cube == cube2.name) {
      hl.removeMesh(cube2);
    } else if (hover_cube == cube3.name) {
      hl.removeMesh(cube3);
    }
  }));

  scene.freezeMaterials();
}

• 創建方塊碰撞體公共方法

//創建方塊碰撞體公共方法
function createBasicRoundedBox(scene, name, size, mass = 0.25, restitution = 0.5, friction = 0.5) {
  const boxSide = size;
  const sphereSide = boxSide * 3.1 / 2;
  const sphere = BABYLON.MeshBuilder.CreateSphere('sphere', {diameter: sphereSide, segments: 16}, scene);
  const box = BABYLON.Mesh.CreateBox('box', boxSide, scene);
  const intersection = BABYLON.CSG.FromMesh(box).intersect(BABYLON.CSG.FromMesh(sphere));
  sphere.dispose();
  box.dispose();
  const roundedBox = intersection.toMesh(
      name,
      new BABYLON.StandardMaterial('roundedBoxMaterial', scene),
      scene
  );
  roundedBox.draggable = true;
  roundedBox.physicsImpostor = new BABYLON.PhysicsImpostor(
      roundedBox,
      BABYLON.PhysicsImpostor.BoxImpostor,
      {mass: mass, restitution: restitution, friction: friction}
  );
  roundedBox.material.freeze();
  roundedBox.material.specularColor = new BABYLON.Color3(0, 0, 0);
  roundedBox.freezeWorldMatrix()
  return roundedBox;
}

后續計劃

Babylon.js

• 自定義啟動界面
• babylonjs-gui 按鈕實現
• babylonjs+ammojs 碰撞體實現
• 將3d界面放入可拖動窗口中

Blockly

• 入門使用blockly
• 自定義block塊
• blockly第三方組件使用
• 接入js-interpreter，步驟運行block塊
• ......(想到啥寫啥)

開源項目GitHub鏈接

https://github.com/Wenbile/Child-Programming-Web

你的點贊是我繼續編寫的動力