为 3D 模型生成插座连接/沿边缘绘制圆柱体

Question

我有这个处理草图，我试图在其中加载模型（.stl 或 .obj）并为每个边缘交叉点构建参数化套接字连接点。这些将是 3D 打印的，并且适当规格的杆将插入它们的孔中。

我已经能够在顶点处绘制球体（在模型上以 红色 表示），但我无法生成 绿色 插槽甚至杆粉红色：

我可以得到模型边缘的坐标：

id: 0 0 {-25.805634,-23.170607,13.6315975} -> 1 {-16.868328,-10.148323,6.785455} f: 2
id: 1 1 {-16.868328,-10.148323,6.785455} -> 2 {-52.833824,-10.148322,16.799314} f: 2
....

有了这些我可以画一个Line3D(Vec3D a, Vec3D b) (toxi.geom.Line3D)

但我不想要 Line3D，我需要在它们之间画一个圆柱体，从而得到杆。如果您愿意的话，可以将线条拉伸或膨胀为 3D 体积...

WETriangleMesh whale, redmesh;

[bla bla bla]
然后在void setup()里面：

for(WingedEdge e : whale.edges.values()) {
    edges.add(e);
    drawSocket(e);
}

void drawSocket(WingedEdge e) {
    // draw size 2 balls at model vertices
    Sphere ball = new Sphere(e.a, 2);
    // convert to mesh at resolution 6 and add to redmesh
    ball.toMesh(redmesh, 6);
}

然后在void draw()：

// draw the mesh with the whale
gfx.mesh(whale);
// color the next mesh red
fill(255,0,0);
// draw the mesh with the spheres
gfx.mesh(redmesh);

我发现没有可以从Vec3D a, Vec3D b 参数就地构建的 3D 形状类。也许创建一个类来使用这两个坐标？

如果就地构建形状太难了，那么也许是变换？ pushMatrix()translate()和popMatrix()?

编辑：已解决，见下文。谢谢！

Answer 1

诀窍是将套接字转换到边缘的一个顶点，并让它们面对相反的顶点。这是一个处理函数，它将像您的鲸鱼一样采用 WETriangleMesh，并返回用于点、插座和杆的网格。我写了一个更完整的例子here。

float socketLength = 30;
float socketRadius = 6;
float rodRadius = 5;
float pointRadius = 10.0;
int resolution = 10;

WETriangleMesh[] convertMeshToRodSockets(WETriangleMesh inMesh) {
  WETriangleMesh[] meshes = new WETriangleMesh[3];

  meshes[0] = new WETriangleMesh();
  meshes[1] = new WETriangleMesh();
  meshes[2] = new WETriangleMesh();

  for (Vertex vert : inMesh.getVertices ()) {
    //Sphere points
    Sphere sphere = new Sphere(vert, pointRadius);
    WETriangleMesh sphereMesh = new WETriangleMesh();
    sphere.toMesh(sphereMesh, resolution);
    meshes[2].addMesh((WETriangleMesh)sphereMesh);
  }

  for (WingedEdge edge : inMesh.edges.values ()) {
    Vec3D pointA = edge.a;
    Vec3D pointB = edge.b;

    //Meshes to store socket shapes
    ZAxisCylinder socket;
    ZAxisCylinder rod;
    WETriangleMesh socketAMesh = new WETriangleMesh();
    WETriangleMesh socketBMesh = new WETriangleMesh();
    WETriangleMesh rodMesh = new WETriangleMesh();

    float distanceBetweenPoints = pointA.distanceTo(pointB);

    //Create sockets and point towards target
    socket = new ZAxisCylinder(new Vec3D(0.0, 0.0, 0.0), socketRadius, socketLength);
    socket.toMesh(socketAMesh, resolution, 0.0);
    socketAMesh.pointTowards(pointB.sub(pointA));

    //Translate socket to start from the center of the point
    socketAMesh.translate( offsetTranslation(pointA, pointB, socketLength ));

    //Create second socket and look in the opposite direction to face the start point
    socket.toMesh(socketBMesh, resolution, 0.0);
    socketBMesh.pointTowards(pointA.sub(pointB));
    socketBMesh.translate( offsetTranslation(pointB, pointA, socketLength ));

    //Create rod with a length matching the distance between the two points
    rod = new ZAxisCylinder(new Vec3D(0.0, 0.0, 0.0), rodRadius, distanceBetweenPoints);
    rod.toMesh(rodMesh, resolution, 0.0);
    rodMesh.pointTowards(pointB.sub(pointA));

    //Translate the rod to the midpoint of both points
    rodMesh.translate(pointA.add(pointB).scale(0.5));

    //Combine meshes together
    meshes[0].addMesh((WETriangleMesh)rodMesh);
    meshes[1].addMesh((WETriangleMesh)socketAMesh);
    meshes[1].addMesh((WETriangleMesh)socketBMesh);
  }

  return meshes;
}

//Function to return a vector that is slightly offset by a length.
Vec3D offsetTranslation(Vec3D a, Vec3D b, float l) {
  return a.interpolateTo(b, (l*0.5 / a.distanceTo(b)) );
}