From 0aa93a6d31a45d8df2d8516567b98967ce04f183 Mon Sep 17 00:00:00 2001
From: Hans Hagen <pragma@wxs.nl>
Date: Fri, 14 Oct 2022 10:56:48 +0200
Subject: 2022-10-14 10:15:00

---
 metapost/context/base/mpxl/mp-math.mpxl | 10 ++++++++
 metapost/context/base/mpxl/mp-tool.mpxl | 41 +++++++++++++++++++++++++++------
 2 files changed, 44 insertions(+), 7 deletions(-)

(limited to 'metapost')

diff --git a/metapost/context/base/mpxl/mp-math.mpxl b/metapost/context/base/mpxl/mp-math.mpxl
index 404d42160..3d9ad81d3 100644
--- a/metapost/context/base/mpxl/mp-math.mpxl
+++ b/metapost/context/base/mpxl/mp-math.mpxl
@@ -172,6 +172,16 @@ else : % decimal
 
 fi ;
 
+%D Variant on post to the mailing list by MC:
+
+vardef atantwo(expr dy, dx) =
+    if dx == 0 :
+        if dy < 0 : - fi pi / 2
+    else :
+        atan(dy/dx) if dx > 0 : if dy < 0 : - else : + fi pi fi
+    fi
+enddef ;
+
 permanent
     m_acos, m_acosh, m_asin, m_asinh, m_atan, m_atantwo, m_atanh, m_cbrt, m_ceil,
     m_copysign, m_cos, m_cosh, m_deg, m_erf, m_erfc, m_exp, m_exptwo, m_expm, m_fabs,
diff --git a/metapost/context/base/mpxl/mp-tool.mpxl b/metapost/context/base/mpxl/mp-tool.mpxl
index 7462b0ace..7b7814eef 100644
--- a/metapost/context/base/mpxl/mp-tool.mpxl
+++ b/metapost/context/base/mpxl/mp-tool.mpxl
@@ -675,12 +675,16 @@ vardef mfun_tool_striped_angle(expr option, p, asked_angle, asked_gap) text extr
         mask := shape rotated used_angle ;
         maximum := max (xpart llcorner mask, xpart urcorner mask, ypart llcorner mask, ypart urcorner mask) ;
         minimum := min (xpart llcorner mask, xpart urcorner mask, ypart llcorner mask, ypart urcorner mask) ;
+        % a hack:
+maximum := maximum + max(xpart urcorner shape, ypart urcorner shape);
+minimum := minimum - max(xpart urcorner shape, ypart urcorner shape);
+        %
         pattern := image (
             if isinner :
                 mfun_tool_striped_angle_action extra ;
                 for s within shape :
                     if stroked s or filled s :
-                        clip currentpicture to pathpart s ;
+                       clip currentpicture to pathpart s ;
                     fi
                 endfor ;
             else :
@@ -741,6 +745,29 @@ def do_stripe_path_a (text asked_spec) (text asked_draw) (expr asked_path) text
     draw image(asked_draw asked_path asked_text) anglestriped(3,0,0) asked_spec ;
 enddef ;
 
+%D A more efficient variant by Mikael:
+
+% path p ; p := fullcircle scaled 3cm && (unitsquare scaled 2cm shifted (4cm,4cm)) && cycle ;
+% draw hatch(p,30,0.2cm) ; draw p ;
+
+vardef hatch(expr p, a, d) =
+    save thestripe, diag, b ; picture thestripe ; numeric diag ; path b ;
+    b := boundingbox p;
+    diag := 0.55 * ( abs((urcorner b) - (llcorner b)) ) ;
+    thestripe := image (
+        draw (-diag,0) -- (diag, 0) &&
+        for i = d step d until diag:
+            (-diag, i) -- (diag, i) &&
+            (-diag,-i) -- (diag,-i) &&
+        endfor nocycle
+        withpen currentpen ;
+    ) ;
+    thestripe := thestripe shifted center b ;
+    thestripe := thestripe rotatedaround(center b, a) ;
+    clip thestripe to p ;
+    thestripe
+enddef ;
+
 %D A few normalizing macros:
 
 % primarydef p xsized w =
@@ -4350,12 +4377,12 @@ tertiarydef p cutbeforefirst q =
     begingroup ;
     save mfun_b, mfun_p ; path mfun_b, mfun_p ; mfun_b := sortedpath (p intersectiontimeslist q) ;
     if (point 0 of mfun_b) <> (-1,-1) :
-        mfun_p := subpath(xpart point 0 of mfun_b, infinity) of p;
+        mfun_p := subpath(xpart point 0 of mfun_b, length p) of p;
     else :
         mfun_p := p ;
     fi ;
     mfun_p
-    endgroup ;
+    endgroup
 enddef ;
 
 tertiarydef p cutafterfirst q =
@@ -4367,7 +4394,7 @@ tertiarydef p cutafterfirst q =
         mfun_p := p ;
     fi ;
     mfun_p
-    endgroup ;
+    endgroup
 enddef ;
 
 
@@ -4375,12 +4402,12 @@ tertiarydef p cutbeforelast q =
     begingroup ;
     save mfun_b, mfun_p ; path mfun_b, mfun_p ; mfun_b := sortedpath (p intersectiontimeslist q) ;
     if (point 0 of mfun_b) <> (-1,-1) :
-        mfun_p := subpath(xpart point (length mfun_b) of mfun_b, infinity) of p;
+        mfun_p := subpath(xpart point (length mfun_b) of mfun_b, length p) of p;
     else :
         mfun_p := p ;
     fi ;
     mfun_p
-    endgroup ;
+    endgroup
 enddef ;
 
 tertiarydef p cutafterlast q =
@@ -4392,7 +4419,7 @@ tertiarydef p cutafterlast q =
         mfun_p := p ;
     fi ;
     mfun_p
-    endgroup ;
+    endgroup
 enddef ;
 
 % I don't want to define this path every time I make a demo:
-- 
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