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DemoMeshHelper.cs
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DemoMeshHelper.cs
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using BepuPhysics.Collidables;
using System;
using System.Numerics;
using BepuUtilities.Memory;
using DemoContentLoader;
using BepuUtilities;
using BepuPhysics.Trees;
namespace Demos;
public static class DemoMeshHelper
{
public static Mesh LoadModel(ContentArchive content, BufferPool pool, string contentName, Vector3 scaling)
{
var meshContent = content.Load<MeshContent>(contentName);
pool.Take<Triangle>(meshContent.Triangles.Length, out var triangles);
for (int i = 0; i < meshContent.Triangles.Length; ++i)
{
triangles[i] = new Triangle(meshContent.Triangles[i].A, meshContent.Triangles[i].B, meshContent.Triangles[i].C);
}
return new Mesh(triangles, scaling, pool);
}
public static Mesh CreateFan(int triangleCount, float radius, Vector3 scaling, BufferPool pool)
{
var anglePerTriangle = 2 * MathF.PI / triangleCount;
pool.Take<Triangle>(triangleCount, out var triangles);
for (int i = 0; i < triangleCount; ++i)
{
var firstAngle = i * anglePerTriangle;
var secondAngle = ((i + 1) % triangleCount) * anglePerTriangle;
ref var triangle = ref triangles[i];
triangle.A = new Vector3(radius * MathF.Cos(firstAngle), 0, radius * MathF.Sin(firstAngle));
triangle.B = new Vector3(radius * MathF.Cos(secondAngle), 0, radius * MathF.Sin(secondAngle));
triangle.C = new Vector3();
}
return new Mesh(triangles, scaling, pool);
}
public static Mesh CreateDeformedPlane(int width, int height, Func<int, int, Vector3> deformer, Vector3 scaling, BufferPool pool, IThreadDispatcher dispatcher = null)
{
pool.Take<Vector3>(width * height, out var vertices);
for (int i = 0; i < width; ++i)
{
for (int j = 0; j < height; ++j)
{
vertices[width * j + i] = deformer(i, j);
}
}
var quadWidth = width - 1;
var quadHeight = height - 1;
var triangleCount = quadWidth * quadHeight * 2;
pool.Take<Triangle>(triangleCount, out var triangles);
for (int i = 0; i < quadWidth; ++i)
{
for (int j = 0; j < quadHeight; ++j)
{
var triangleIndex = (j * quadWidth + i) * 2;
ref var triangle0 = ref triangles[triangleIndex];
ref var v00 = ref vertices[width * j + i];
ref var v01 = ref vertices[width * j + i + 1];
ref var v10 = ref vertices[width * (j + 1) + i];
ref var v11 = ref vertices[width * (j + 1) + i + 1];
triangle0.A = v00;
triangle0.B = v01;
triangle0.C = v10;
ref var triangle1 = ref triangles[triangleIndex + 1];
triangle1.A = v01;
triangle1.B = v11;
triangle1.C = v10;
}
}
pool.Return(ref vertices);
return new Mesh(triangles, scaling, pool, dispatcher);
}
/// <summary>
/// Creates a bunch of nodes and associates them with leaves with absolutely no regard for where the leaves are.
/// </summary>
static void CreateDummyNodes(ref Tree tree, int nodeIndex, int nodeLeafCount, ref int leafCounter)
{
ref var node = ref tree.Nodes[nodeIndex];
node.A.LeafCount = nodeLeafCount / 2;
if (node.A.LeafCount > 1)
{
node.A.Index = nodeIndex + 1;
tree.Metanodes[node.A.Index] = new Metanode { IndexInParent = 0, Parent = nodeIndex };
CreateDummyNodes(ref tree, node.A.Index, node.A.LeafCount, ref leafCounter);
}
else
{
tree.Leaves[leafCounter] = new Leaf(nodeIndex, 0);
node.A.Index = Tree.Encode(leafCounter++);
}
node.B.LeafCount = nodeLeafCount - node.A.LeafCount;
if (node.B.LeafCount > 1)
{
node.B.Index = nodeIndex + node.A.LeafCount;
tree.Metanodes[node.B.Index] = new Metanode { IndexInParent = 1, Parent = nodeIndex };
CreateDummyNodes(ref tree, node.B.Index, node.B.LeafCount, ref leafCounter);
}
else
{
tree.Leaves[leafCounter] = new Leaf(nodeIndex, 1);
node.B.Index = Tree.Encode(leafCounter++);
}
}
/// <summary>
/// Takes a large number of triangles and creates a Mesh from them, but does not attempt to compute any bounds.
/// The topology of the mesh's acceleration structure is based entirely on the order of the triangles.
/// This is intended to be used with <see cref="Tree.Refit"/>, <see cref="Tree.RefitAndRefine(BufferPool, int, float)"/>,
/// or <see cref="Tree.RefitAndRefineMultithreadedContext.RefitAndRefine(ref Tree, BufferPool, IThreadDispatcher, int, float)"/> to provide bounds and higher quality.
/// </summary>
/// <param name="triangles">Large number of triangles to build a mesh from.</param>
/// <param name="scaling">Scale to use for the mesh shape.</param>
/// <param name="pool">Buffer pool to allocate resources for the mesh.</param>
/// <returns>Created mesh with no bounds.</returns>
/// <remarks>This exists primarily as an easy example of how to work around the slow sequential default mesh building options for very large meshes, like heightmaps.
/// It is not optimized anywhere close to as much as it could be.
/// In the future, I'd like to give the Tree and Mesh much faster (and multithreaded) constructors that achieve quality and speed in one shot.</remarks>
public unsafe static Mesh CreateGiantMeshFastWithoutBounds(Buffer<Triangle> triangles, Vector3 scaling, BufferPool pool)
{
if (triangles.Length < 128)
{
//The special logic isn't necessary for tiny meshes, and we also don't handle the corner case of leaf counts <= 2. Just use the regular constructor.
return new Mesh(triangles, scaling, pool);
}
var mesh = Mesh.CreateWithoutTreeBuild(triangles, scaling, pool);
int leafCounter = 0;
CreateDummyNodes(ref mesh.Tree, 0, triangles.Length, ref leafCounter);
for (int i = 0; i < triangles.Length; ++i)
{
ref var t = ref triangles[i];
mesh.Tree.GetBoundsPointers(i, out var min, out var max);
*min = Vector3.Min(t.A, Vector3.Min(t.B, t.C));
*max = Vector3.Max(t.A, Vector3.Max(t.B, t.C));
}
return mesh;
}
/// <summary>
/// Takes a very large number of triangles and turns them into a mesh by simply assuming that the input triangles are in an order that'll happen to produce an okay-ish acceleration structure.
/// If you have a large height map, you might want to use this instead of the Mesh constructor's default sweep build or insertion builder.
/// The quality is much lower than a sweep build (or even insertion build for that matter), but it can be orders of magnitude faster.
/// Consider using refinement to get the tree quality closer to the sweep builder's quality afterwards.
/// </summary>
/// <param name="triangles">Large number of triangles to build a mesh from.</param>
/// <param name="scaling">Scale to use for the mesh shape.</param>
/// <param name="pool">Buffer pool to allocate resources for the mesh.</param>
/// <returns>Created mesh.</returns>
/// <remarks>This exists primarily as an easy example of how to work around the slow sequential default mesh building options for very large meshes, like heightmaps.
/// It is not optimized anywhere close to as much as it could be.
/// In the future, I'd like to give the Tree and Mesh much faster (and multithreaded) constructors that achieve quality and speed in one shot.</remarks>
public static Mesh CreateGiantMeshFast(Buffer<Triangle> triangles, Vector3 scaling, BufferPool pool)
{
var mesh = CreateGiantMeshFastWithoutBounds(triangles, scaling, pool);
//None of the nodes actually have bounds. Give them some now.
mesh.Tree.Refit();
return mesh;
}
/// <summary>
/// Takes a very large number of triangles and turns them into a mesh by first creating a dummy topology and then incrementally refining it.
/// If you have a large height map, you might want to use this instead of the Mesh constructor's default sweep build or insertion builder.
/// The quality can approach <see cref="Tree.SweepBuild(BufferPool, Buffer{BoundingBox})"/> at a much lower cost thanks to a more efficient algorithm and multithreading.
/// </summary>
/// <param name="triangles">Large number of triangles to build a mesh from.</param>
/// <param name="scaling">Scale to use for the mesh shape.</param>
/// <param name="pool">Buffer pool to allocate resources for the mesh.</param>
/// <returns>Created mesh.</returns>
/// <remarks>This exists primarily as an easy example of how to work around the slow sequential default mesh building options for very large meshes, like heightmaps.
/// It is not optimized anywhere close to as much as it could be.
/// In the future, I'd like to give the Tree and Mesh much faster (and multithreaded) constructors that achieve quality and speed in one shot.</remarks>
public static Mesh CreateGiantMeshWithRefinements(Buffer<Triangle> triangles, Vector3 scaling, BufferPool pool, Tree.RefitAndRefineMultithreadedContext context, IThreadDispatcher threadDispatcher, int refinementIterationCount = 8)
{
var mesh = CreateGiantMeshFastWithoutBounds(triangles, scaling, pool);
//None of the nodes actually have bounds. Give them some now.
for (int i = 0; i < refinementIterationCount; ++i)
context.RefitAndRefine(ref mesh.Tree, pool, threadDispatcher, i, 20);
return mesh;
}
}