Currently I am writing on my thesis for university, the theme I am working on is 3D Visualization of hierarchical structures using cone trees.
I want to do is to draw a cone and arrange a number of spheres at the bottom of the cone. The spheres should be arranged according to the radius and the number of spheres correctly.
As you can imagine I need a lot of these cone/sphere combinations.
First Attempt
I was able to find some tutorials that helped with drawing cones and spheres.
Cone
public Cone(GraphicsDevice device, float height, int tessellation, string name, List<Sphere> children) { //prepare children and calculate the children spacing and radius of the cone if (children == null || children.Count == 0) { throw new ArgumentNullException("children"); } this.Height = height; this.Name = name; this.Children = children; //create the cone if (tessellation < 3) { throw new ArgumentOutOfRangeException("tessellation"); } //Create a ring of triangels around the outside of the cones bottom for (int i = 0; i < tessellation; i++) { Vector3 normal = this.GetCircleVector(i, tessellation); // add the vertices for the top of the cone base.AddVertex(Vector3.Up * height, normal); //add the bottom circle base.AddVertex(normal * this.radius + Vector3.Down * height, normal); //Add indices base.AddIndex(i * 2); base.AddIndex(i * 2 + 1); base.AddIndex((i * 2 + 2) % (tessellation * 2)); base.AddIndex(i * 2 + 1); base.AddIndex((i * 2 + 3) % (tessellation * 2)); base.AddIndex((i * 2 + 2) % (tessellation * 2)); } //create flate triangle to seal the bottom this.CreateCap(tessellation, height, this.Radius, Vector3.Down); base.InitializePrimitive(device); }Sphere
public void Initialize(GraphicsDevice device, Vector3 qi) { int verticalSegments = this.Tesselation; int horizontalSegments = this.Tesselation * 2; //single vertex on the bottom base.AddVertex((qi * this.Radius) + this.lowering, Vector3.Down); for (int i = 0; i < verticalSegments; i++) { float latitude = ((i + 1) * MathHelper.Pi / verticalSegments) - MathHelper.PiOver2; float dy = (float)Math.Sin(latitude); float dxz = (float)Math.Cos(latitude); //Create a singe ring of latitudes for (int j = 0; j < horizontalSegments; j++) { float longitude = j * MathHelper.TwoPi / horizontalSegments; float dx = (float)Math.Cos(longitude) * dxz; float dz = (float)Math.Sin(longitude) * dxz; Vector3 normal = new Vector3(dx, dy, dz); base.AddVertex(normal * this.Radius, normal); } } // Finish with a single vertex at the top of the sphere. AddVertex((qi * this.Radius) + this.lowering, Vector3.Up); // Create a fan connecting the bottom vertex to the bottom latitude ring. for (int i = 0; i < horizontalSegments; i++) { AddIndex(0); AddIndex(1 + (i + 1) % horizontalSegments); AddIndex(1 + i); } // Fill the sphere body with triangles joining each pair of latitude rings. for (int i = 0; i < verticalSegments - 2; i++) { for (int j = 0; j < horizontalSegments; j++) { int nextI = i + 1; int nextJ = (j + 1) % horizontalSegments; base.AddIndex(1 + i * horizontalSegments + j); base.AddIndex(1 + i * horizontalSegments + nextJ); base.AddIndex(1 + nextI * horizontalSegments + j); base.AddIndex(1 + i * horizontalSegments + nextJ); base.AddIndex(1 + nextI * horizontalSegments + nextJ); base.AddIndex(1 + nextI * horizontalSegments + j); } } // Create a fan connecting the top vertex to the top latitude ring. for (int i = 0; i < horizontalSegments; i++) { base.AddIndex(CurrentVertex - 1); base.AddIndex(CurrentVertex - 2 - (i + 1) % horizontalSegments); base.AddIndex(CurrentVertex - 2 - i); } base.InitializePrimitive(device); }The tricky part now is to arrange the spheres at the bottom of the cone. I tried is to draw just the cone and then draw the spheres. I need a lot of these cones, so it would be pretty hard to calculate all the positions correctly.
Second Attempt
So the second try was to generate a object that builds all vertices of the cone and all of the spheres at once. So I was hoping to render a cone with all its spheres arranged correctly. After a short debug I found out that the cone is created and the first sphere, when it turn of the second sphere I am running into an OutOfBoundsException of ushort.MaxValue.
Cone and Spheres
public ConeWithSpheres(GraphicsDevice device, float height, float coneDiameter, float sphereDiameter, int coneTessellation, int sphereTessellation, int numberOfSpheres) { if (coneTessellation < 3) { throw new ArgumentException(string.Format("{0} is to small for the tessellation of the cone. The number must be greater or equal to 3", coneTessellation)); } if (sphereTessellation < 3) { throw new ArgumentException(string.Format("{0} is to small for the tessellation of the sphere. The number must be greater or equal to 3", sphereTessellation)); } //set properties this.Height = height; this.ConeDiameter = coneDiameter; this.SphereDiameter = sphereDiameter; this.NumberOfChildren = numberOfSpheres; //end set properties //generate the cone this.GenerateCone(device, coneTessellation); //generate the spheres //vector that defines the Y position of the sphere on the cones bottom Vector3 lowering = new Vector3(0, 0.888f, 0); this.GenerateSpheres(device, sphereTessellation, numberOfSpheres, lowering); } // ------ GENERATE CONE ------ private void GenerateCone(GraphicsDevice device, int coneTessellation) { int doubleTessellation = coneTessellation * 2; //Create a ring of triangels around the outside of the cones bottom for (int index = 0; index < coneTessellation; index++) { Vector3 normal = this.GetCircleVector(index, coneTessellation); //add the vertices for the top of the cone base.AddVertex(Vector3.Up * this.Height, normal); //add the bottom of the cone base.AddVertex(normal * this.ConeRadius + Vector3.Down * this.Height, normal); //add indices base.AddIndex(index * 2); base.AddIndex(index * 2 + 1); base.AddIndex((index * 2 + 2) % doubleTessellation); base.AddIndex(index * 2 + 1); base.AddIndex((index * 2 + 3) % doubleTessellation); base.AddIndex((index * 2 + 2) % doubleTessellation); } //create flate triangle to seal the bottom this.CreateCap(coneTessellation, this.Height, this.ConeRadius, Vector3.Down); base.InitializePrimitive(device); } // ------ GENERATE SPHERES ------ private void GenerateSpheres(GraphicsDevice device, int sphereTessellation, int numberOfSpheres, Vector3 lowering) { int verticalSegments = sphereTessellation; int horizontalSegments = sphereTessellation * 2; for (int childCount = 1; childCount < numberOfSpheres; childCount++) { //single vertex at the bottom of the sphere base.AddVertex((this.GetCircleVector(childCount, this.NumberOfChildren) * this.SphereRadius) + lowering, Vector3.Down); for (int verticalSegmentsCount = 0; verticalSegmentsCount < verticalSegments; verticalSegmentsCount++) { float latitude = ((verticalSegmentsCount + 1) * MathHelper.Pi / verticalSegments) - MathHelper.PiOver2; float dy = (float)Math.Sin(latitude); float dxz = (float)Math.Cos(latitude); //create a single ring of latitudes for (int horizontalSegmentsCount = 0; horizontalSegmentsCount < horizontalSegments; horizontalSegmentsCount++) { float longitude = horizontalSegmentsCount * MathHelper.TwoPi / horizontalSegments; float dx = (float)Math.Cos(longitude) * dxz; float dz = (float)Math.Sin(longitude) * dxz; Vector3 normal = new Vector3(dx, dy, dz); base.AddVertex((normal * this.SphereRadius) + lowering, normal); } } //finish with a single vertex at the top of the sphere base.AddVertex((this.GetCircleVector(childCount, this.NumberOfChildren) * this.SphereRadius) + lowering, Vector3.Up); //create a fan connecting the bottom vertex to the bottom latitude ring for (int i = 0; i < horizontalSegments; i++) { base.AddIndex(0); base.AddIndex(1 + (i + 1) % horizontalSegments); base.AddIndex(1 + i); } //Fill the sphere body with triangles joining each pair of latitude rings for (int i = 0; i < verticalSegments - 2; i++) { for (int j = 0; j < horizontalSegments; j++) { int nextI = i + 1; int nextJ = (j + 1) % horizontalSegments; base.AddIndex(1 + i * horizontalSegments + j); base.AddIndex(1 + i * horizontalSegments + nextJ); base.AddIndex(1 + nextI * horizontalSegments + j); base.AddIndex(1 + i * horizontalSegments + nextJ); base.AddIndex(1 + nextI * horizontalSegments + nextJ); base.AddIndex(1 + nextI * horizontalSegments + j); } } //create a fan connecting the top vertiex to the top latitude for (int i = 0; i < horizontalSegments; i++) { base.AddIndex(this.CurrentVertex - 1); base.AddIndex(this.CurrentVertex - 2 - (i + 1) % horizontalSegments); base.AddIndex(this.CurrentVertex - 2 - i); } base.InitializePrimitive(device); } }Any ideas how I could fix this?