Add MinDistanceSampling for 3D Ball (#1121)

* add MinDistanceSampling for 3D Ball

* Update src/sampling/mindistance.jl

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* add test

* Minor adjustments

* Fix method ambiguity

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Júlio Hoffimann <julio.hoffimann@gmail.com>

src/sampling/mindistance.jl

@@ -37,15 +37,19 @@ MinDistanceSampling(α, ρ, δ, metric) = MinDistanceSampling(addunit(α, u"m"),
 
 MinDistanceSampling(α::T; ρ=T(0.65), δ=100, metric=Euclidean()) where {T} = MinDistanceSampling(α, ρ, δ, metric)
 
-function sample(rng::AbstractRNG, d::Domain, method::MinDistanceSampling)
+sample(rng::AbstractRNG, d::Domain, method::MinDistanceSampling) = _sample(rng, d, method)
+
+sample(rng::AbstractRNG, b::Ball, method::MinDistanceSampling) = _sample(rng, b, method)
+
+function _sample(rng::AbstractRNG, obj, method::MinDistanceSampling)
   # retrieve parameters
   α = method.α
   ρ = method.ρ
   δ = method.δ
   m = method.metric
 
   # total volume/area of the object
-  V = sum(measure, d)
+  V = measure(obj)
 
   # expected number of Poisson samples
   # for relative radius (Lagae & Dutré 2007)
@@ -55,7 +59,7 @@ function sample(rng::AbstractRNG, d::Domain, method::MinDistanceSampling)
   O = ceil(Int, δ * ustrip(N))
 
   # oversample the object
-  points = sample(rng, d, HomogeneousSampling(O))
+  points = sample(rng, obj, HomogeneousSampling(O))
 
   # collect points into point set
   𝒫 = PointSet(collect(points))

test/sampling.jl

@@ -392,6 +392,12 @@ end
   poly = PolyArea(cart.([(-44.20065308, -21.12284851), (-44.20324135, -21.122799875), (-44.20582962, -21.12275124)]))
   ps = sample(poly, MinDistanceSampling(3.2423333333753135e-5))
   @test length(ps) > 0
+
+  ball = Ball(cart(10, 10), T(3))
+  ps = sample(ball, MinDistanceSampling(1.0))
+  n = length(ps)
+  @test all(∈(ball), ps)
+  @test all(norm(ps[i] - ps[j]) ≥ T(1.0) * u"m" for i in 1:n for j in (i + 1):n)
 end
 
 @testitem "FibonacciSampling" setup = [Setup] begin