/// <summary>
/// Calculate mesh only once ... no worry about animation, no accurate bounding box
/// </summary>
/// <param name="bones"></param>
/// <param name="mesh"></param>
/// <returns></returns>
/// <remarks>
/// https://gamedev.stackexchange.com/questions/46332/mesh-manipulation-on-gpu-vs-cpu
/// https://gamedev.stackexchange.com/questions/43986/calculate-an-aabb-for-bone-animated-model
/// </remarks>
AnimationHittableGeometryComponent ConstructMesh(Matrix4x4[] bones, CMOAnimateMeshComponent mesh)
{
var pos = new List <Vector3>();
var norms = new List <Vector3>();
var indeces = new List <int>();
for (int indx = 0; indx < mesh.VertexBuffers.Count; indx++)
{
var vb = mesh.VertexBuffers[indx];
var vertices = new Vertex[vb.Length];
for (var i = 0; i < vb.Length; i++)
{
// Retrieve skinning information for vertex
var skin = new SkinningVertex();
if (mesh.SkinningVertexBuffers.Count > 0)
{
skin = mesh.SkinningVertexBuffers[indx][i];
}
// Create vertex
vertices[i] = new Vertex(vb[i].Position, vb[i].Normal, (Vector4)vb[i].Color, vb[i].UV, skin);
//the same matrix as in animation.hlsl
var skinTransform = Matrix4x4.Transpose(
bones[skin.BoneIndex0] * skin.BoneWeight0 +
bones[skin.BoneIndex1] * skin.BoneWeight1 +
bones[skin.BoneIndex2] * skin.BoneWeight2 +
bones[skin.BoneIndex3] * skin.BoneWeight3);
pos.Add(Vector3.Transform(vb[i].Position, skinTransform));
norms.Add(Vector3.TransformNormal(vb[i].Normal, skinTransform));
}
}
var offset = 0;
// Initialize index buffers
for (var i = 0; i < mesh.IndexBuffers.Count; i++)
{
var ib = mesh.IndexBuffers[i];
foreach (var ii in ib)
{
indeces.Add(offset + (int)ii);
}
offset += mesh.VertexBuffers[i].Length;
}
var geo = new AnimationHittableGeometryComponent();
geo.Positions = pos.ToImmutableArray();
geo.Indices = indeces.ToImmutableArray();
geo.Normals = norms.ToImmutableArray();
geo.IsModified = true;
return(geo);
}
OrientationComponent CreateStickOnComponent(AnimationHittableGeometryComponent geo)
{
var box = geo.Box;
var com = new OrientationComponent();
com.AxisUpLocal = -Vector3.UnitZ; //local axis of current anim mesh by default
com.AttachPointLocal = box.GetCenter() + com.AxisUpLocal * box.Size().Z / 2; //the bottom point of Box for stick on terrain
com.FrontDirectionLocal = Vector3.UnitY;
return(com);
}