From 2d8a85053cccc6b94edf90bad18a7662141bae82 Mon Sep 17 00:00:00 2001
From: Anshul Singhvi <anshulsinghvi@gmail.com>
Date: Sat, 20 Apr 2024 15:23:55 -0400
Subject: [PATCH 1/2] Basic predicate skeleton

---
 Project.toml                       |  1 +
 src/GeometryOps.jl                 |  1 +
 src/methods/clipping/predicates.jl | 37 ++++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+)
 create mode 100644 src/methods/clipping/predicates.jl

diff --git a/Project.toml b/Project.toml
index 11987eb2d..9a0a9019b 100644
--- a/Project.toml
+++ b/Project.toml
@@ -5,6 +5,7 @@ version = "0.1.3"
 
 [deps]
 CoordinateTransformations = "150eb455-5306-5404-9cee-2592286d6298"
+ExactPredicates = "429591f6-91af-11e9-00e2-59fbe8cec110"
 GeoInterface = "cf35fbd7-0cd7-5166-be24-54bfbe79505f"
 GeometryBasics = "5c1252a2-5f33-56bf-86c9-59e7332b4326"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
diff --git a/src/GeometryOps.jl b/src/GeometryOps.jl
index dc52c7d17..50de92d7e 100644
--- a/src/GeometryOps.jl
+++ b/src/GeometryOps.jl
@@ -26,6 +26,7 @@ include("methods/barycentric.jl")
 include("methods/centroid.jl")
 include("methods/distance.jl")
 include("methods/equals.jl")
+include("methods/clipping/predicates.jl")
 include("methods/clipping/clipping_processor.jl")
 include("methods/clipping/coverage.jl")
 include("methods/clipping/cut.jl")
diff --git a/src/methods/clipping/predicates.jl b/src/methods/clipping/predicates.jl
new file mode 100644
index 000000000..a3dc30f79
--- /dev/null
+++ b/src/methods/clipping/predicates.jl
@@ -0,0 +1,37 @@
+module Predicates
+
+using ExactPredicates
+using ExactPredicates.Codegen
+using ExactPredicates.Codegen: group!, coord, @genpredicate
+
+using ExactPredicates: ext, inp
+
+# This is the implementation of r_cross_s from 2 points in the `_intersection_points` file.
+@genpredicate function isparallel(a1 :: 2, a2 :: 2, b1 :: 2, b2 :: 2)
+    r = a2 - a1
+    s = b2 - b1
+    group!(r...)
+    group!(s...)
+    ext(r, s)
+end
+
+@genpredicate function iscollinear(a1::2, a2::2, b1::2, b2::2)
+    Δqp = b1 - a1
+    s = b2 - b1
+    group!(Δqp...)
+    group!(s...)
+    ext(s, Δqp)
+end
+
+import .Predicates
+
+# Predicates.r_cross_s(...)
+
+#=
+using MultiFloats
+function isparallel_adaptive(a1, a2, b1, b2)
+    r = Float64x2.(a2) - Float64x2.(a1)
+    s = Float64x2.(b2) - Float64x2.(b1)
+    return sign(Predicates.ext(r, s))
+end
+=#
\ No newline at end of file

From f3eaf1750fa3274f96152aa33edd7d516a8f3faa Mon Sep 17 00:00:00 2001
From: Anshul Singhvi <anshulsinghvi@gmail.com>
Date: Sat, 20 Apr 2024 15:32:59 -0400
Subject: [PATCH 2/2] Add tabs and a comment

---
 src/methods/clipping/predicates.jl | 48 +++++++++++++++++++-----------
 1 file changed, 30 insertions(+), 18 deletions(-)

diff --git a/src/methods/clipping/predicates.jl b/src/methods/clipping/predicates.jl
index a3dc30f79..85b912af5 100644
--- a/src/methods/clipping/predicates.jl
+++ b/src/methods/clipping/predicates.jl
@@ -1,26 +1,30 @@
 module Predicates
 
-using ExactPredicates
-using ExactPredicates.Codegen
-using ExactPredicates.Codegen: group!, coord, @genpredicate
+    using ExactPredicates
+    using ExactPredicates.Codegen
+    using ExactPredicates.Codegen: group!, coord, @genpredicate
 
-using ExactPredicates: ext, inp
+    using ExactPredicates: ext, inp
 
-# This is the implementation of r_cross_s from 2 points in the `_intersection_points` file.
-@genpredicate function isparallel(a1 :: 2, a2 :: 2, b1 :: 2, b2 :: 2)
-    r = a2 - a1
-    s = b2 - b1
-    group!(r...)
-    group!(s...)
-    ext(r, s)
-end
+    # This is the implementation of r_cross_s from 2 points in the `_intersection_points` file.
+    # 0 == parallel
+    @genpredicate function isparallel(a1 :: 2, a2 :: 2, b1 :: 2, b2 :: 2)
+        r = a2 - a1
+        s = b2 - b1
+        group!(r...)
+        group!(s...)
+        ext(r, s)
+    end
+    # This is the implementation of `iscollinear` from `intersection_points`.
+    # 0 == parallel.
+    @genpredicate function iscollinear(a1::2, a2::2, b1::2, b2::2)
+        Δqp = b1 - a1
+        s = b2 - b1
+        group!(Δqp...)
+        group!(s...)
+        ext(s, Δqp)
+    end
 
-@genpredicate function iscollinear(a1::2, a2::2, b1::2, b2::2)
-    Δqp = b1 - a1
-    s = b2 - b1
-    group!(Δqp...)
-    group!(s...)
-    ext(s, Δqp)
 end
 
 import .Predicates
@@ -28,10 +32,18 @@ import .Predicates
 # Predicates.r_cross_s(...)
 
 #=
+# If we want to inject adaptivity, we would do:
 using MultiFloats
 function isparallel_adaptive(a1, a2, b1, b2)
     r = Float64x2.(a2) - Float64x2.(a1)
     s = Float64x2.(b2) - Float64x2.(b1)
     return sign(Predicates.ext(r, s))
 end
+function isparallel(a1, a2, b1, b2)
+    # try Predicates.isparallel_naive(a1, a2, b1, b2)
+    # check the error bound there
+    # then try isparallel_adaptive(a1, a2, b1, b2)
+    # then try Predicates.isparallel_slow
+    # then try isparallel
+end
 =#
\ No newline at end of file