Change back the name of rtgrpblib_draw_elliptical_arc to rtgrpblib_draw_circular_arc

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 18 insertions, 8 deletions

diff --git a/librifunktionsteckensnittsglyfrasteriseringsprogrambiblioteket.h b/librifunktionsteckensnittsglyfrasteriseringsprogrambiblioteket.h
index aa6f4ce..ef53fea 100644
--- a/librifunktionsteckensnittsglyfrasteriseringsprogrambiblioteket.h
+++ b/librifunktionsteckensnittsglyfrasteriseringsprogrambiblioteket.h
@@ -128,19 +128,29 @@ void rtgrpblib_draw_cubic_bezier(RTGRPBLIB_RASTER *restrict raster,
                                  double x4, double y4);
 
 /**
- * Draw a elliptical arc
+ * Draw a circular arc
  * 
  * @param  raster      The drawing buffer
- * @param  x0, y0      The midpoint of the ellipse
- * @param  semiwidth   Half the width of the ellipse
- * @param  semiheight  Half the height of the ellipse
+ * @param  x0, y0      The midpoint of the circle
+ * @param  semiwidth   Half the width of the circle
+ * @param  semiheight  Half the height of the circle
  * @param  start       The angular starting point of the arc, in radians
  * @param  end         The angular end point of the arc, in radians
+ *
+ * Rather than specify a radius, a semimajor and semiminor is
+ * specified, despite this, the shape is called a circular rather
+ * than elliptical, this is because the function is indented to
+ * draw a circular arc on a image with different horizontal
+ * and vertical cell densities; note an elliptical arc on an image
+ * with the same horizontal as vertical cell density. This is
+ * why the function doesn't provide a way to rotate the ellipse:
+ * it's a circle, not an ellipse, and circles are perfectly
+ * symmetrical
  */
-void rtgrpblib_draw_elliptical_arc(RTGRPBLIB_RASTER *restrict raster,
-                                   double x0, double y0,
-                                   double semiwidth, double semiheight,
-                                   double start, double end);
+void rtgrpblib_draw_circular_arc(RTGRPBLIB_RASTER *restrict raster,
+                                 double x0, double y0,
+                                 double semiwidth, double semiheight,
+                                 double start, double end);
 
 
 #if defined(__clang__)