From d6ca3d65aada2cdf1ba076e65c7fe59e98a25924 Mon Sep 17 00:00:00 2001
From: Alberto Griggio <agriggio@users.noreply.github.com>
Date: Fri, 17 Aug 2018 15:30:36 +0200
Subject: [PATCH] catmull-rom: ensure that the curve evaluation is exact at the
 control points

---
 rtengine/diagonalcurves.cc | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/rtengine/diagonalcurves.cc b/rtengine/diagonalcurves.cc
index 3955c8e01..fc65951fa 100644
--- a/rtengine/diagonalcurves.cc
+++ b/rtengine/diagonalcurves.cc
@@ -317,7 +317,10 @@ inline void catmull_rom_spline(int n_points,
     double c, d, A1_x, A1_y, A2_x, A2_y, A3_x, A3_y;
     double B1_x, B1_y, B2_x, B2_y, C_x, C_y;
 
-    for (i = 0; i < n_points; ++i) {
+    res_x.push_back(p1_x);
+    res_y.push_back(p1_y);
+
+    for (i = 1; i < n_points-1; ++i) {
         t = t1 + space * i;
         
         c = (t1 - t)/(t1 - t0);
@@ -353,6 +356,9 @@ inline void catmull_rom_spline(int n_points,
         res_x.push_back(C_x);
         res_y.push_back(C_y);
     }
+
+    res_x.push_back(p2_x);
+    res_y.push_back(p2_y);
 }