From b8b1df01e7e6cc9053eb53417da4caa6bda18552 Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Sun, 23 Oct 2022 15:40:37 +0200
Subject: [PATCH] fixed some linewidth issues

---
 drawing.cpp | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/drawing.cpp b/drawing.cpp
index adc55230..fbc58626 100644
--- a/drawing.cpp
+++ b/drawing.cpp
@@ -809,7 +809,13 @@ void dqi_poly::gldraw() {
 #endif
 
 EX ld scale_at(const shiftmatrix& T) {
-  if(GDIM == 3 && pmodel == mdPerspective) return 1 / abs((tC0(unshift(T)))[2]);
+  if(GDIM == 3 && pmodel == mdPerspective) {
+    ld z = (tC0(unshift(T)))[2];
+    if(z == 0) return 1;
+    z = 1 / abs(z);
+    if(z > 10) return 10;
+    return z;
+    }
   if(sol) return 1;
   hyperpoint h1, h2, h3;
   applymodel(tC0(T), h1);
@@ -841,6 +847,17 @@ EX ld linewidthat(const shiftpoint& h) {
       return dfc;
       }
     }
+  else if(hyperbolic && pmodel == mdRelPerspective) {
+    if(abs(h[3]) < 1e-6) return 1;
+    return 1 / (1 + abs(h[3]));
+    }
+  else if(sl2 && pmodel == mdRelPerspective) {
+    if(abs(h[2]) < 1e-6) return 1;
+    return 1 / (1 + abs(h[2]));
+    }
+  else if(hyperbolic && GDIM == 3 && pmodel == mdPerspective && pconf.alpha == 0 && h[3] < 0.99) {
+    return 1;
+    }
   else if(perfect_linewidth >= (inHighQual ? 1 : 2)) {
     hyperpoint h0 = h.h / zlevel(h.h);
     shiftmatrix T = shiftless(rgpushxto0(h0), h.shift);