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基于webgl(threejs)的路面编辑

用户3158888

发布于 2022-09-21 01:49:37

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代码可运行

文章被收录于专栏：计算机图形学前端可视化 WebGL计算机图形学前端可视化 WebGL

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代码可运行

楔子

在很多应用中，特别是一些园区类的应用。都需要对园区的地面环境进行展示，路面就是地面的一部分。通常的做法是，都是建模的时候把相关的元素都建好，然后导入到展示系统中进行展示。不过有些情况下，可能建模并不太方便，所以三维编辑器可以直接进行简单的路面编辑显得挺有必要。

路面对象扩展

简单的路面希望能够通过一个路径来生成。我们知道在threejs中有通过路径生成管路的对象，参考文章WebGL管网展示(及TubeGeometry优化)，管路的横截面是一个圆形。道路的横截面期望是一个矩形，因此，我们可以仿照管路的思路制作一个类似的对象PathRectGeometry，只是计算顶点的时候，横截面不再使用圆形，而是使用一个矩形，代码如下：

 let points = [new Vec3(-width/2,-height/2,0),new Vec3(-width/2,height/2,0),
        new Vec3(width/2,height/2,0),new Vec3(width/2,-height/2,0)] 
            if(!scope.clockwise) {
                points = [new Vec3(-width/2,-height/2,0),new Vec3(width/2,-height/2,0),
                    new Vec3(width/2,height/2,0),new Vec3(-width/2,height/2,0)];
            }
      for( let j = 0;j <= points.length;j ++) {
        let jj = j == points.length ? 0 : j; 
        let point = points[jj];
        let radius = Math.hypot(point.x,point.y);
        const sin = point.y / radius;
        const cos = point.x / radius;

          normal.x = ( cos * N.x + sin * B.x );
                normal.y = ( cos * N.y + sin * B.y );
                normal.z = ( cos * N.z + sin * B.z );
                normal.normalize();

                normals.push( 0,1,0 );
            // vertex
                vertex.x = P.x + radius * normal.x;
                vertex.y = P.y + radius * normal.y;
                vertex.z = P.z + radius * normal.z;

                vertices.push( vertex.x, vertex.y, vertex.z );
      }

通过PathRectGeometry创建对象的效果如下图所示：

路面编辑

通过在平面上面打点来构建直线和贝塞尔曲线，然后通过构建得线条了生成路径，通过路径就可以生成路面效果，

 graph.getView().addEventListener("click", (event) => {
        let now = new Date().getTime();
        if (t != 0 && now - t < 500) {
          return;
        }
        t = now;
        if (path) {
          let pos = graph.getPositionOnPlaneByEvent(event, plane);
          constraintsHorizontalOrVertical(path, pos);
          path.lineTo(pos.x, pos.y, pos.z);
          tempPath = path.clone(tempPath);
          tempRoad.geometry.path = tempPath;
        }
      })

大概得过程如下所示：

在生成得路径上，会有很多控制点，拖动控制点可以二次修改路径：

生成连接处

两条路得连接处会有斑马线之类得，点击生成斑马线，可以通过算法自动计算斑马线，

// 找到road1 到road2的joint
    function createJointShape(road1, road2) {
      let path = road1.geometry.path;
      let path2 = road2.geometry.path;
      let lastPoint = path.points.at(-1);
      let lastCurve = path.curves.at(-1);
      let curves = path2.curves;
      console.log(curves);
      let minCurve, minDist = Infinity,
        minPoint
      for (let i = 0; i < curves.length; i++) {
        let curve = curves[i];
        if (curve.type == "LineCurve3") {
          let {
            dist,
            point
          } = findClosestPoint(lastPoint, curve.v1, curve.v2);
          if (dist < minDist) {
            minDist = dist;
            minPoint = point;
            minCurve = curve;
          }
        }
      }
      console.log(minCurve, minDist, minPoint);

      let v1 = lastCurve.v1,
        v2 = lastCurve.v2;
      let tagent = new dt.Vec3().subVectors(v2, v1);
      let up = new dt.Vec3(0, 1, 0);
      let cross = new dt.Vec3().cross(up, tagent);
      cross.normalize();
      let halfRoadWidth = 50;
      cross.multiplyScalar(halfRoadWidth);
      let cross2 = cross.clone().multiplyScalar(3.0);

      let p1 = lastPoint.clone().add(cross),
        p2 = lastPoint.clone().sub(cross);

      let sub = new dt.Vec3().subVectors(minPoint, lastPoint);
      console.log(sub.length(), minDist, halfRoadWidth)
      sub.setLength(minDist - halfRoadWidth);

      let joinPoint = new dt.Vec3().addVectors(lastPoint, sub);

      let halfSub = sub.clone().multiplyScalar(0.75);
      let p3Center = p1.clone().add(halfSub);
      let p4Center = p2.clone().add(halfSub);

      let p3 = joinPoint.clone().add(cross2);
      let p4 = joinPoint.clone().sub(cross2)

      let newPath = new dt.ShapePath();

      newPath.moveTo(p2.x, p2.z);
      newPath.quadraticCurveTo(p4Center.x, p4Center.z, p4.x, p4.z);
      newPath.lineTo(p3.x, p3.z);
      newPath.quadraticCurveTo(p3Center.x, p3Center.z, p1.x, p1.z);
      // newPath.closePath();
      // let geo = new dt.PathTubeGeometry(newPath, 64, 2);
      // let tube = new dt.Mesh(geo);

      let shapePath = newPath;

      const simpleShapes = shapePath.toShapes(true);

      var texture = graph.loadTexture("./road/001.jpg", {
        wrapT: dt.RepeatWrapping,
        wrapS: dt.RepeatWrapping,
      });
      texture.repeat.set(1 / 100, 1 / 100);
      texture.anisotropy = 16;

      let m1 = new dt.BasicMaterial({
        //  flatShading:true,
        map: texture,
        // envMap:envMap,
        // reflectivity:0.4,
        color: 0xffffff,
        toneMapped: false,
      });

      var geometry = new dt.ExtrudeGeometry(simpleShapes, {
        depth: 1,
        bevelEnabled: false,
        vertical: true,
      });
      var mesh = new dt.Mesh(geometry, m1);
      window.graph.getDataManager().add(mesh);

      road1.add(mesh);
    }