SimulationTree.Meshes 0.3.9

Meshes

Data type for storing 3D shapes/geometry.

Usage

Below is an example of building a quad mesh from scratch:

Mesh mesh = new(world);
USpan<Vector3> positions = mesh.CreatePositions(4);
USpan<Vector2> uvs = mesh.CreateUVs(4);
USpan<Vector3> normals = mesh.CreateNormals(4);
positions[0] = new(0, 0, 0);
positions[1] = new(1, 0, 0);
positions[2] = new(1, 1, 0);
positions[3] = new(0, 1, 0);
uvs[0] = new(0, 0);
uvs[1] = new(1, 0);
uvs[2] = new(1, 1);
uvs[3] = new(0, 1);
normals[0] = new(0, 0, 1);
normals[1] = new(0, 0, 1);
normals[2] = new(0, 0, 1);
normals[3] = new(0, 0, 1);
mesh.AddTriangle(0, 1, 2);
mesh.AddTriangle(2, 3, 0);

USpan<uint> indices = quadMesh.GetIndices();

Updating after creation

Whenever arrays of a mesh are modified in length, the version of the mesh increments. This gives feedback for systems to update when necessary. But for the cases where the array lengths remain the same and only contents change, the IncrementVersion function should be used:

USpan<Vector3> positions = mesh.GetPositions();
positions[0] *= 2;
positions[1] *= 2;
positions[2] *= 2;
positions[3] *= 2;
mesh.IncrementVersion();

positions = mesh.ResizePositions(8);
positions[4] = new(0, 0, 0);
positions[5] = new(1, 0, 0);
positions[6] = new(1, 1, 0);
positions[7] = new(0, 1, 0);
//incrementing version is already done

Assembling

Often mesh data is wanted in a specific formats . The Assemble function can be used to retrieve a flat list of float values containing vertex data in the specified order:

USpan<Mesh.Channel> channels = [Mesh.Channel.Position, Mesh.Channel.UV];
USpan<float> vertexData = stackalloc float[(int)channels.GetVertexSize() * 4];
quadMesh.Assemble(vertexData, channels);