Added isCCW function.

Author: evetion

Project.toml

@@ -1,7 +1,7 @@
 name = "LibGEOS"
 uuid = "a90b1aa1-3769-5649-ba7e-abc5a9d163eb"
 license = "MIT"
-version = "0.6.10"
+version = "0.6.11"
 
 [deps]
 CEnum = "fa961155-64e5-5f13-b03f-caf6b980ea82"

src/geos_functions.jl

@@ -271,6 +271,15 @@ function getCoordinates(ptr::GEOSCoordSeq, context::GEOSContext = _context)
     coordseq
 end
 
+function isCCW(ptr::GEOSCoordSeq, context::GEOSContext=_context)::Bool
+    d = UInt8[1]
+    GC.@preserve result = GEOSCoordSeq_isCCW_r(context.ptr, ptr, pointer(d))
+    if result == C_NULL
+        error("LibGEOS: Error in GEOSInterpolateNormalized")
+    end
+    Bool(d[1])
+end
+
 # -----
 # Linear referencing functions -- there are more, but these are probably sufficient for most purposes
 # -----

test/test_geos_functions.jl

@@ -52,6 +52,13 @@ end
     c = LibGEOS.createPoint(LibGEOS.createCoordSeq(Vector{Float64}[[1, 2]]))
     @test LibGEOS.getCoordinates(LibGEOS.getCoordSeq(c))[1] ≈ [1, 2] atol = 1e-5
 
+    # isCCW
+    seq = Vector{Float64}[[-1, 0], [0, 0], [10, 0], [10, 10], [0, 10], [-1, 0]]
+    a = LibGEOS.createCoordSeq(seq)
+    @test LibGEOS.isCCW(a)
+    a = LibGEOS.createCoordSeq(reverse(seq))
+    @test !LibGEOS.isCCW(a)
+
     # Polygons and Holes
     shell = LibGEOS.createLinearRing(
         Vector{Float64}[[0, 0], [10, 0], [10, 10], [0, 10], [0, 0]],