x01.EarthRun
<div id="cnblogs_post_body">月亮绕着地球转，地球绕着太阳转，一个 TranslateTransform3D + RotationTransform3D 即可搞定。难的是球体（Sphere）绘制。作为球体，由经度、纬度划分为一小块一小块的。球体的绘制，说白了，就是这一小块一小块的绘制。除上下极点外，每小块由四个点（Point3D）构成，即两个三角形。
现在，只要求出了这些 Point3D，问题即可解决。为简便，不妨设球心 O 为（0，0，0），半径 r 为 1 。（WPF 3D 坐标：左到右 x 轴，下到上 y 轴，屏幕里到外 z 轴）
如何求球面某经纬度交叉点 A （x，y，z）的 3D 坐标呢？
1. 忽略 z 轴，设角 AOX （纬度偏移）度数为 a，则 x = cos(a); y = sin(a); 同理，z = cos(a);
2. 设经度偏移角度 AOZ 为 b，此时，y 不变。忽略 y 轴，则 x = cos(a)*sin(b); z = cos(a)*cos(b);
即：(cos(a)*sin(b), sin(a), cos(a)*cos(b)) 为 A 3D 坐标。参考代码如下：
<div class="cnblogs_code" >http://images.cnblogs.com/OutliningIndicators/ContractedBlock.gifhttp://images.cnblogs.com/OutliningIndicators/ExpandedBlockStart.gifTrangulate<div id="cnblogs_code_open_ae55b94f-540d-4811-8eb8-86e133ade64d" class="cnblogs_code_hide">protected void Triangulate(DependencyPropertyChangedEventArgs e, Point3DCollection vertices, Vector3DCollection normals, Int32Collection indices, PointCollection textures) { vertices.Clear(); normals.Clear(); indices.Clear(); textures.Clear(); for (int stack = 0; stack <= Stacks; stack++) { double phi = Math.PI / 2 - stack * Math.PI / Stacks; double y = Radius * Math.Sin(phi); double scale = -Radius * Math.Cos(phi); for (int slice = 0; slice <= Slices; slice++) { double theta = slice * 2 * Math.PI / Slices; double x = scale * Math.Sin(theta); double z = scale * Math.Cos(theta); Vector3D normal = new Vector3D(x, y, z); normals.Add(normal); vertices.Add(normal + Center); textures.Add(new Point((double)slice / Slices, (double)stack / Stacks)); } } // stack == 0 for (int slice = 0; slice < Slices; slice++) { indices.Add(slice + 1); indices.Add(Slices + 1 + slice); indices.Add(Slices + 1 + slice + 1); } for (int stack = 1; stack < Stacks - 1; stack++) { for (int slice = 0; slice < Slices; slice++) { indices.Add(stack * (Slices + 1) + slice); indices.Add((stack + 1) * (Slices + 1) + slice); indices.Add(stack * (Slices + 1) + slice + 1); indices.Add(stack * (Slices + 1) + slice + 1); indices.Add((stack + 1) * (Slices + 1) + slice); indices.Add((stack + 1) * (Slices + 1) + slice + 1); } } // stack == Stacks - 1 for (int slice = 0; slice < Slices; slice++) { int stack = Stacks - 1; indices.Add(stack * (Slices + 1) + slice); indices.Add((stack + 1) * (Slices + 1) + slice); indices.Add(stack * (Slices + 1) + slice + 1); } }
页:
[1]