From b4753e66e29af0b6087f591838069deb9689b78f Mon Sep 17 00:00:00 2001
From: jaseg <git@jaseg.de>
Date: Sun, 26 Mar 2023 00:40:43 +0100
Subject: WIP

---
 svg-flatten/include/geom2d.hpp | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

(limited to 'svg-flatten/include')

diff --git a/svg-flatten/include/geom2d.hpp b/svg-flatten/include/geom2d.hpp
index 47cf3be..9650575 100644
--- a/svg-flatten/include/geom2d.hpp
+++ b/svg-flatten/include/geom2d.hpp
@@ -113,9 +113,38 @@ namespace gerbolyze {
 
             double doc2phys_skew(double dist_doc) {
                 /* https://math.stackexchange.com/a/3521141 */
+                /* https://stackoverflow.com/a/70381885 */
                 /* xx yx x0
                  * xy yy y0 */
-                s_x = sqrt();
+                double s_x = sqrt(xx*xx + xy*xy);
+
+                if (xx == 0 && xy == 0) {
+                    return std::numeric_limits<double>::infinity;
+                }
+
+                double theta = atan2(xy, xx);
+                double f = (xx*yy - xy*yx);
+
+                if (f == 0) {
+                    return std::numeric_limits<double>::infinity;
+                }
+
+                double m = (xx*yx + yy*xy) / f;
+
+                double f = xx + m*xy;
+                double s_y = 0;
+
+                if (f == 0) {
+                    f = m*xx - xy;
+                    if (f == 0) {
+                        return std::numeric_limits<double>::infinity;
+                    }
+                    s_y = yx*s_x / f;
+                } else {
+                    s_y = yy*s_x / f;
+                }
+
+                return s_x - s_y > 
             }
 
             double doc2phys_min(double dist_doc) {
-- 
cgit