star-cpr

commit a8a6aeffbaabe5af8733717e9e54a7ec2d83bde0
parent 3dbf6253d07b1433f727e0ee62974c08398cd9d8
Author: Christophe Coustet <christophe.coustet@meso-star.com>
Date:   Thu,  7 Sep 2023 10:14:10 +0200

Add is_cw and reverse to allow component orientation management

Diffstat:
M
src/scpr.h
 | 
13
+++++++++++++
M
src/scpr_polygon.c
 | 
49
+++++++++++++++++++++++++++++++++++++++++++++++++

2 files changed, 62 insertions(+), 0 deletions(-)
diff --git a/src/scpr.h b/src/scpr.h
@@ -230,6 +230,19 @@ scpr_polygon_get_position
    const size_t ivert,
    double position[2]);
 
+/* Get the polygon component orientation.
+ * Only meaningful for simple polygons. */
+SCPR_API res_T
+scpr_polygon_is_component_cw
+  (const struct scpr_polygon* polygon,
+   const size_t icomponent,
+   int* cw);
+
+SCPR_API res_T
+scpr_polygon_reverse_component
+  (struct scpr_polygon* polygon,
+   const size_t icomponent);
+
 /* Logical comparison for polygons.
  * Component order and orientation are not considered. */
 SCPR_API res_T
diff --git a/src/scpr_polygon.c b/src/scpr_polygon.c
@@ -456,6 +456,55 @@ error:
 }
 
 res_T
+scpr_polygon_is_component_cw
+  (const struct scpr_polygon* polygon,
+   const size_t icomponent,
+   int* cw)
+{
+  res_T res = RES_OK;
+
+  if(!polygon || !cw || icomponent > polygon->paths.size()) {
+    res = RES_BAD_ARG;
+    goto error;
+  }
+
+  *cw = !Clipper2Lib::IsPositive(polygon->paths[icomponent]);
+
+exit:
+  return res;
+error:
+  goto exit;
+}
+
+res_T
+scpr_polygon_reverse_component
+  (struct scpr_polygon* polygon,
+   const size_t icomponent)
+{
+  res_T res = RES_OK;
+  Clipper2Lib::Point64* data;
+  size_t i, j;
+
+  if(!polygon || icomponent > polygon->paths.size()) {
+    res = RES_BAD_ARG;
+    goto error;
+  }
+
+  i = 0;
+  j = polygon->paths[icomponent].size();
+  data = polygon->paths[icomponent].data();
+  while(i != j && i != --j) {
+    SWAP(Clipper2Lib::Point64, data[i], data[j]);
+    i++; /* Not in SWAP macro! */
+  }
+
+exit:
+  return res;
+error:
+  goto exit;
+}
+
+res_T
 scpr_polygon_eq
   (const struct scpr_polygon* polygon1,
    const struct scpr_polygon* polygon2,