public unsafe void BuildConvexHull2D()
{
// Build circle.
var expectedCom = new float3(4, 5, 3);
const int n = 1024;
float3 * points = stackalloc float3[n];
Aabb domain = Aabb.Empty;
for (int i = 0; i < n; ++i)
{
float angle = (float)i / n * 2 * (float)math.PI;
points[i] = expectedCom + new float3(math.cos(angle), math.sin(angle), 0);
domain.Include(points[i]);
}
ConvexHullBuilderStorage builder = new ConvexHullBuilderStorage(8192, Allocator.Temp, domain, 0.0f, ConvexHullBuilder.IntResolution.High);
for (int i = 0; i < n; ++i)
{
builder.Builder.AddPoint(points[i]);
}
builder.Builder.UpdateHullMassProperties();
var massProperties = builder.Builder.HullMassProperties;
Assert.IsTrue(math.all(math.abs(massProperties.CenterOfMass - expectedCom) < 1e-4f));
Assert.AreEqual(math.PI, massProperties.SurfaceArea, 1e-4f);
}
//
// Reference implementations of queries using simple brute-force methods
//
static unsafe float RefConvexConvexDistance(ref ConvexHull a, ref ConvexHull b, MTransform aFromB)
{
bool success = false;
if (a.NumVertices + b.NumVertices < 64) // too slow without burst
{
// Build the minkowski difference in a-space
int maxNumVertices = a.NumVertices * b.NumVertices;
Aabb aabb = Aabb.Empty;
for (int iB = 0; iB < b.NumVertices; iB++)
{
float3 vertexB = Math.Mul(aFromB, b.Vertices[iB]);
for (int iA = 0; iA < a.NumVertices; iA++)
{
float3 vertexA = a.Vertices[iA];
aabb.Include(vertexA - vertexB);
}
}
ConvexHullBuilderStorage diffStorage = new ConvexHullBuilderStorage(maxNumVertices, Allocator.Temp, aabb, 0.0f, ConvexHullBuilder.IntResolution.Low);
ref ConvexHullBuilder diff = ref diffStorage.Builder;
success = true;
for (int iB = 0; iB < b.NumVertices; iB++)
{
float3 vertexB = Math.Mul(aFromB, b.Vertices[iB]);
for (int iA = 0; iA < a.NumVertices; iA++)
{
float3 vertexA = a.Vertices[iA];
diff.AddPoint(vertexA - vertexB, (uint)(iA | iB << 16));
}
}
float distance = 0.0f;
if (success && diff.Dimension == 3)
{
// Find the closest triangle to the origin
distance = float.MaxValue;
bool penetrating = true;
foreach (int t in diff.Triangles.Indices)
{
ConvexHullBuilder.Triangle triangle = diff.Triangles[t];
float3 v0 = diff.Vertices[triangle.GetVertex(0)].Position;
float3 v1 = diff.Vertices[triangle.GetVertex(1)].Position;
float3 v2 = diff.Vertices[triangle.GetVertex(2)].Position;
float3 n = diff.ComputePlane(t).Normal;
DistanceQueries.Result result = DistanceQueries.TriangleSphere(v0, v1, v2, n, float3.zero, 0.0f, MTransform.Identity);
if (result.Distance < distance)
{
distance = result.Distance;
}
penetrating = penetrating & (math.dot(n, -result.NormalInA) < 0.0f); // only penetrating if inside of all planes
}
if (penetrating)
{
distance = -distance;
}
distance -= a.ConvexRadius + b.ConvexRadius;
}
else
{
success = false;
}
diffStorage.Dispose();
if (success)
{
return(distance);
}
}
