segmentize

src/typed-geometry/feature/objects.hh

@@ -22,6 +22,7 @@
 #include <typed-geometry/functions/objects/plane.hh>
 #include <typed-geometry/functions/objects/project.hh>
 #include <typed-geometry/functions/objects/rasterize.hh>
+#include <typed-geometry/functions/objects/segmentize.hh>
 #include <typed-geometry/functions/objects/size.hh>
 #include <typed-geometry/functions/objects/tangent.hh>
 #include <typed-geometry/functions/objects/triangle.hh>

src/typed-geometry/functions/objects/segmentize.hh

+#pragma once
+
+#include <typed-geometry/feature/basic.hh>
+#include <typed-geometry/functions/objects/edges.hh>
+
+namespace tg
+{
+/// calls on_segment for each edge of the object
+/// on_segment: (tg::segment) -> void
+template <class Obj, class OnSegment, std::enable_if_t<has_edges_of<Obj>, int> = 0>
+constexpr void segmentize(Obj const& obj, OnSegment&& on_segment)
+{
+    for (auto&& s : edges_of(obj))
+        on_segment(s);
+}
+
+/// calls on_segment for a discretized version of the sphere
+template <class ScalarT, class TraitsT, class OnSegment>
+void segmentize(sphere<2, ScalarT, 2, TraitsT> const& s, int segs, OnSegment&& on_segment)
+{
+    TG_ASSERT(segs >= 3);
+
+    using dir_t = dir<2, ScalarT>;
+
+    auto const dir_of = [&](int i) -> dir_t {
+        if (i == 0 || i == segs)
+            return dir_t(1, 0);
+
+        auto [sa, ca] = sin_cos(tau<ScalarT> * i / ScalarT(segs));
+        return dir_t(ca, sa);
+    };
+    auto const pos_of = [&](int i) {
+        auto d = dir_of(i);
+        return s.center + d * s.radius;
+    };
+
+    auto prev = pos_of(0);
+    for (auto i = 1; i <= segs; ++i)
+    {
+        auto curr = pos_of(i);
+        on_segment(tg::segment<2, ScalarT>(prev, curr));
+        prev = curr;
+    }
+}
+template <class ScalarT, class TraitsT, class OnSegment>
+void segmentize(sphere<2, ScalarT, 3, TraitsT> const& s, int segs, OnSegment&& on_segment)
+{
+    TG_ASSERT(segs >= 3);
+    auto const dx = any_normal(s.normal);
+    auto const dy = cross(s.normal, dx);
+
+    using dir_t = dir<2, ScalarT>;
+
+    auto const dir_of = [&](int i) -> dir_t {
+        if (i == 0 || i == segs)
+            return dir_t(1, 0);
+
+        auto [sa, ca] = sin_cos(tau<ScalarT> * i / ScalarT(segs));
+        return dir_t(ca, sa);
+    };
+    auto const pos_of = [&](int i) {
+        auto d = dir_of(i) * s.radius;
+        return s.center + dx * d.x + dy * d.y;
+    };
+
+    auto prev = pos_of(0);
+    for (auto i = 1; i <= segs; ++i)
+    {
+        auto curr = pos_of(i);
+        on_segment(tg::segment<3, ScalarT>(prev, curr));
+        prev = curr;
+    }
+}
+}

src/typed-geometry/functions/objects/triangulate.hh

@@ -34,8 +34,8 @@ void triangulate_uv(sphere<3, ScalarT, 3, TraitsT> const& s, int segs_u, int seg
         else if (v == segs_v)
             return dir_t(0, -1, 0);
 
-        auto [su, cu] = tg::sin_cos(tau<ScalarT> * (u == segs_u ? 0 : u) / ScalarT(segs_u));
-        auto [sv, cv] = tg::sin_cos(pi<ScalarT> * v / ScalarT(segs_v));
+        auto [su, cu] = sin_cos(tau<ScalarT> * (u == segs_u ? 0 : u) / ScalarT(segs_u));
+        auto [sv, cv] = sin_cos(pi<ScalarT> * v / ScalarT(segs_v));
 
         return dir_t(sv * su, cv, sv * cu);
     };
@@ -52,7 +52,7 @@ void triangulate_uv(sphere<3, ScalarT, 3, TraitsT> const& s, int segs_u, int seg
             auto p1 = pos_of(i, 1);
             auto p2 = pos_of(i + 1, 1);
 
-            on_triangle(tg::triangle3(p0, p1, p2));
+            on_triangle(tg::triangle<3, ScalarT>(p0, p1, p2));
         }
     }
 
@@ -66,8 +66,8 @@ void triangulate_uv(sphere<3, ScalarT, 3, TraitsT> const& s, int segs_u, int seg
             auto p10 = pos_of(i + 1, j + 0);
             auto p11 = pos_of(i + 1, j + 1);
 
-            on_triangle(tg::triangle3(p00, p01, p11));
-            on_triangle(tg::triangle3(p00, p11, p10));
+            on_triangle(tg::triangle<3, ScalarT>(p00, p01, p11));
+            on_triangle(tg::triangle<3, ScalarT>(p00, p11, p10));
         }
     }
 
@@ -79,7 +79,7 @@ void triangulate_uv(sphere<3, ScalarT, 3, TraitsT> const& s, int segs_u, int seg
             auto p1 = pos_of(i, segs_v - 1);
             auto p2 = pos_of(i + 1, segs_v - 1);
 
-            on_triangle(tg::triangle3(p0, p2, p1));
+            on_triangle(tg::triangle<3, ScalarT>(p0, p2, p1));
         }
     }
 }