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@Doprez
Created November 11, 2023 05:10
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Get Vertices and Indices from a mesh in Stride3d
using Stride.Games;
using Stride.Rendering;
using System;
using Stride.Core.Serialization;
using Stride.Core;
using Stride.Physics;
using System.Collections.Generic;
using Stride.Core.Mathematics;
public static class MeshExtensions
{
public static (List<Vector3> verts, List<int> indices) GetMeshVerticesAndIndices(this Model model, IGame game)
{
return GetMeshData(model, game.Services, game);
}
static unsafe (List<Vector3> verts, List<int> indices) GetMeshData(Model model, IServiceRegistry services, IGame game)
{
Matrix[] nodeTransforms = null;
int totalVerts = 0, totalIndices = 0;
foreach (var meshData in model.Meshes)
{
totalVerts += meshData.Draw.VertexBuffers[0].Count;
totalIndices += meshData.Draw.IndexBuffer.Count;
}
var combinedVerts = new List<Vector3>(totalVerts);
var combinedIndices = new List<int>(totalIndices);
foreach (var meshData in model.Meshes)
{
var vBuffer = meshData.Draw.VertexBuffers[0].Buffer;
var iBuffer = meshData.Draw.IndexBuffer.Buffer;
byte[] verticesBytes = vBuffer.GetData<byte>(game.GraphicsContext.CommandList); ;
byte[] indicesBytes = iBuffer.GetData<byte>(game.GraphicsContext.CommandList); ;
if ((verticesBytes?.Length ?? 0) == 0 || (indicesBytes?.Length ?? 0) == 0)
{
throw new InvalidOperationException(
$"Failed to find mesh buffers while attempting to build a {nameof(StaticMeshColliderShape)}. " +
$"Make sure that the {nameof(model)} is either an asset on disk, or has its buffer data attached to the buffer through '{nameof(AttachedReference)}'\n" +
$"You can also explicitly build a {nameof(StaticMeshColliderShape)} using the second constructor instead of this one.");
}
int vertMappingStart = combinedVerts.Count;
fixed (byte* bytePtr = verticesBytes)
{
var vBindings = meshData.Draw.VertexBuffers[0];
int count = vBindings.Count;
int stride = vBindings.Declaration.VertexStride;
for (int i = 0, vHead = vBindings.Offset; i < count; i++, vHead += stride)
{
var pos = *(Vector3*)(bytePtr + vHead);
if (nodeTransforms != null)
{
Matrix posMatrix = Matrix.Translation(pos);
Matrix.Multiply(ref posMatrix, ref nodeTransforms[meshData.NodeIndex], out var finalMatrix);
pos = finalMatrix.TranslationVector;
}
combinedVerts.Add(pos);
}
}
fixed (byte* bytePtr = indicesBytes)
{
if (meshData.Draw.IndexBuffer.Is32Bit)
{
foreach (int i in new Span<int>(bytePtr + meshData.Draw.IndexBuffer.Offset, meshData.Draw.IndexBuffer.Count))
{
combinedIndices.Add(vertMappingStart + i);
}
}
else
{
foreach (ushort i in new Span<ushort>(bytePtr + meshData.Draw.IndexBuffer.Offset, meshData.Draw.IndexBuffer.Count))
{
combinedIndices.Add(vertMappingStart + i);
}
}
}
}
return (combinedVerts, combinedIndices);
}
}
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