star-cpr

commit 5da0a0368ae784afa09150d8b4cc13ee918dc0f4
parent e8b3d8f1e3e18f9e51768c318a52c21a8b86a6d2
Author: Christophe Coustet <christophe.coustet@meso-star.com>
Date:   Fri, 15 Sep 2023 15:29:03 +0200

Add component_in_component and get_vertex_in_component API calls

Diffstat:
M
src/scpr.h
 | 
20
+++++++++++++++++++-
M
src/scpr_polygon.c
 | 
110
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-

2 files changed, 128 insertions(+), 2 deletions(-)
diff --git a/src/scpr.h b/src/scpr.h
@@ -253,7 +253,14 @@ scpr_polygon_eq
    const struct scpr_polygon* polygon2,
    int* is_eq);
 
-/* Check if a given vertex is in a given component. */
+/* Return a vertex that is inside a component. */
+SCPR_API res_T
+scpr_get_vertex_in_component
+  (const struct scpr_polygon* polygon,
+   const size_t icomponent,
+   double vertex[2]);
+
+/* Check if a vertex is in a component. */
 SCPR_API res_T
 scpr_is_vertex_in_component
   (const struct scpr_polygon* polygon,
@@ -261,6 +268,17 @@ scpr_is_vertex_in_component
    const double vertex[2],
    int* situation); /* +1: inside, 0: on, -1: outside */
 
+/* Check if a component is inside a component, given the 2 components do not
+ * overlap.
+ * Only meaningful for 2 simple polygons. */
+SCPR_API res_T
+scpr_is_component_in_component
+  (const struct scpr_polygon* polygon1,
+   const size_t icomponent1,
+   const struct scpr_polygon* polygon2,
+   const size_t icomponent2,
+   int* c1_is_in_c2);
+
 SCPR_API res_T
 scpr_polygon_dump_to_obj
   (struct scpr_polygon* polygon,
diff --git a/src/scpr_polygon.c b/src/scpr_polygon.c
@@ -551,6 +551,53 @@ error:
 }
 
 res_T
+scpr_get_vertex_in_component
+  (const struct scpr_polygon* polygon,
+   const size_t icomponent,
+   double vertex[2])
+{
+  size_t i, p1sz;
+  Clipper2Lib::Point64 p0, c;
+  Clipper2Lib::PointInPolygonResult in;
+  res_T res = RES_OK;
+
+  if(!polygon || !vertex || icomponent >= polygon->paths.size()) {
+    res = RES_BAD_ARG;
+    goto error;
+  }
+
+  /* Find the center of the segment between vertex #0 and vertex #i
+   * If it is inside the polygon return it */
+  p0 = polygon->paths[icomponent][0];
+  p1sz = polygon->paths[icomponent].size();
+  for(i = 2; i < polygon->paths[0].size(); i++) {
+    Clipper2Lib::Point64 pi = polygon->paths[icomponent][i];
+    if(p1sz == 3) {
+      /* Special case of a triangle: get the barycenter */
+      Clipper2Lib::Point64 p1 = polygon->paths[icomponent][1];
+      c = (p0 + p1 + pi) * 0.3333333;
+    } else {
+      c = (p0 + pi) * 0.5;
+    }
+    TRY(in = Clipper2Lib::PointInPolygon(c, polygon->paths[icomponent]));
+    if(in == Clipper2Lib::PointInPolygonResult::IsOn) {
+      int64_t tmp64[2];
+      tmp64[0] = c.x; tmp64[1] = c.y;
+      ERR(scpr_device_unscale(polygon->device, tmp64, 2, vertex));
+      break; /* Found! */
+    }
+  }
+  /* Should not be there: the component is either ill-formed or too thin to host
+   * a vertex in its inside! */
+  res = RES_BAD_ARG;
+
+exit:
+  return res;
+error:
+  goto exit;
+}
+
+res_T
 scpr_is_vertex_in_component
   (const struct scpr_polygon* polygon,
    const size_t icomponent,
@@ -570,7 +617,6 @@ scpr_is_vertex_in_component
   ERR(scpr_device_scale(polygon->device, vertex, 2, tmp64));
   TRY(pt.Init(SPLIT2(tmp64)));
   TRY(in = Clipper2Lib::PointInPolygon(pt, polygon->paths[icomponent]));
-  enum class PointInPolygonResult { IsOn, IsInside, IsOutside };
   switch(in) {
     case Clipper2Lib::PointInPolygonResult::IsOn:
       *situation = 0;
@@ -590,6 +636,68 @@ error:
 }
 
 res_T
+scpr_is_component_in_component
+  (const struct scpr_polygon* polygon1,
+   const size_t icomponent1,
+   const struct scpr_polygon* polygon2,
+   const size_t icomponent2,
+   int* c1_is_in_c2)
+{
+  size_t i, p1sz;
+  Clipper2Lib::Point64 p0, c;
+  Clipper2Lib::PointInPolygonResult in;
+  res_T res = RES_OK;
+
+  if(!polygon1 || icomponent1 >= polygon1->paths.size()
+     || !polygon2 || icomponent2 >= polygon2->paths.size()
+     || ! c1_is_in_c2)
+  {
+    res = RES_BAD_ARG;
+    goto error;
+  }
+
+  /* First find a vertex that is inside polygon1 */
+  p0 = polygon1->paths[icomponent1][0];
+  p1sz = polygon1->paths[icomponent1].size();
+  for(i = 2; i < p1sz; i++) {
+    Clipper2Lib::Point64 pi = polygon1->paths[icomponent1][i];
+    if(p1sz == 3) {
+      /* Special case of a triangle: get the barycenter */
+      Clipper2Lib::Point64 p1 = polygon1->paths[icomponent1][1];
+      c = (p0 + p1 + pi) * 0.3333333;
+    } else {
+      c = (p0 + pi) * 0.5;
+    }
+    TRY(in = Clipper2Lib::PointInPolygon(c, polygon1->paths[icomponent1]));
+    if(in != Clipper2Lib::PointInPolygonResult::IsInside)
+      continue;
+    /* c is in polygon1; check its situation against polygon2 */
+    TRY(in = Clipper2Lib::PointInPolygon(c, polygon2->paths[icomponent2]));
+    switch(in) {
+      case Clipper2Lib::PointInPolygonResult::IsOn:
+        /* The 2 components overlap! */
+        res = RES_BAD_ARG;
+        goto error;
+      case Clipper2Lib::PointInPolygonResult::IsOutside:
+        *c1_is_in_c2 = 0;
+        goto exit;
+      case Clipper2Lib::PointInPolygonResult::IsInside:
+        *c1_is_in_c2 = 1;
+        goto exit;
+    }
+    break;
+  }
+  /* Should not be there: component1 is either ill-formed or too thin to host
+   * a vertex in its inside! */
+  res = RES_BAD_ARG;
+
+exit:
+  return res;
+error:
+  goto exit;
+}
+
+res_T
 scpr_polygon_dump_to_obj
   (struct scpr_polygon* polygon,
    FILE* stream)