From 5f33d6b51b60471e22ba43d48783cd1df56f1fd6 Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Wed, 16 Sep 2020 13:51:21 +0200
Subject: [PATCH] drawing:: broken_projection as a separate function

---
 drawing.cpp | 145 ++++++++++++++++++++++++++++------------------------
 1 file changed, 78 insertions(+), 67 deletions(-)

diff --git a/drawing.cpp b/drawing.cpp
index 8c03e6aa..10a1ad6f 100644
--- a/drawing.cpp
+++ b/drawing.cpp
@@ -1501,8 +1501,85 @@ EX namespace ods {
 #endif
   EX }
 
+/** @brief render in a broken projection; return false if normal rendering is not applicable */
+bool broken_projection(dqi_poly& p0) {
+  int broken_coord = models::get_broken_coord(pmodel);
+  static bool in_broken = false;
+  if(broken_coord && !in_broken) {
+
+    int zcoord = broken_coord;
+    int ycoord = 3 - zcoord;
+    
+    vector<hyperpoint> all;
+    for(int i=0; i<p0.cnt; i++) 
+      all.push_back(p0.V.T * glhr::gltopoint((*p0.tab)[p0.offset+i]));
+    int fail = 0;
+    int last_fail;
+    
+    auto break_in = [&] (hyperpoint a, hyperpoint b) {
+      return a[0] * b[0] <= 0 && (a[0] * b[zcoord] - b[0] * a[zcoord]) * (a[0] - b[0]) < 0;
+      };
+    
+    for(int i=0; i<p0.cnt-1; i++) 
+      if(break_in(all[i], all[i+1]))
+        last_fail = i, fail++;
+    vector<glvertex> v;
+    dqi_poly p = p0;
+    p.tab = &v;
+    p.offset = 0;
+    p.V.T = Id;
+    if(fail) {
+      dynamicval<bool> ib(in_broken, true);
+      ld part = ilerp(all[last_fail][0], all[last_fail+1][0], 0);
+      hyperpoint initial = normalize(lerp(all[last_fail], all[last_fail+1], 1 - (1-part) * .99));
+      bool have_initial = true;
+      v.push_back(glhr::pointtogl(initial));
+      last_fail++;
+      int at = last_fail;
+      do {
+        v.push_back(glhr::pointtogl(all[at]));
+        if(at == p0.cnt-1 && all[at] != all[0]) {
+          p.cnt = isize(v); p.draw(); v.clear(); at = 0;
+          have_initial = false;
+          }
+        int next = at+1;
+        if(next == p0.cnt) next = 0;
+        if(break_in(all[at], all[next])) {
+          ld part = ilerp(all[at][0], all[next][0], 0);
+          hyperpoint final = normalize(lerp(all[at], all[next], part * .99));
+          v.push_back(glhr::pointtogl(final));
+          if(have_initial) {
+            int max = 4 << vid.linequality;
+            if(final[0] * initial[0] > 0) {
+              for(int i=1; i<=max; i++)
+                v.push_back(glhr::pointtogl(lerp(final, initial, i * 1. / max)));
+              }
+            else {
+              hyperpoint end = Hypc;
+              end[ycoord] = final[ycoord] > 0 ? 1 : -1;
+              for(int i=1; i<=max; i++)
+                v.push_back(glhr::pointtogl(lerp(final, end, i * 1. / max)));
+              for(int i=1; i<=max; i++)
+                v.push_back(glhr::pointtogl(lerp(end, initial, i * 1. / max)));
+              }
+            }
+          p.cnt = isize(v); p.draw(); v.clear();
+          initial = normalize(lerp(all[at], all[next], 1 - (1-part) * .99));
+          have_initial = true;
+          v.push_back(glhr::pointtogl(initial));
+          }
+        at = next;
+        }
+      while(at != last_fail);
+      return true;
+      }
+    }
+  return false;
+  }
+
 void dqi_poly::draw() {
   if(flags & POLY_DEBUG) debug_this();
+
   if(debugflags & DF_VERTEX) {
     println(hlog, tie(V, offset, cnt, offset_texture, outline, linewidth, flags, intester, cache), (cell*) tinf);
     for(int i=0; i<cnt; i++) print(hlog, (*tab)[i]);
@@ -1546,73 +1623,7 @@ void dqi_poly::draw() {
     return;
     }
   
-  int broken_coord = models::get_broken_coord(pmodel);
-  static bool in_broken = false;
-  if(broken_coord && !in_broken) {
-
-    int zcoord = broken_coord;
-    int ycoord = 3 - zcoord;
-    
-    vector<hyperpoint> all;
-    for(int i=0; i<cnt; i++) 
-      all.push_back(V.T * glhr::gltopoint((*tab)[offset+i]));
-    int fail = 0;
-    int last_fail;
-    for(int i=0; i<cnt-1; i++) 
-      if(all[i][0] * all[i+1][0] <= 0 && (all[i][0] * all[i+1][zcoord] - all[i+1][0] * all[i][zcoord]) * (all[i][0] - all[i+1][0]) < 0)
-        last_fail = i, fail++;
-    vector<glvertex> v;
-    dqi_poly p = *this;
-    p.tab = &v;
-    p.offset = 0;
-    p.V.T = Id;
-    if(fail) {
-      dynamicval<bool> ib(in_broken, true);
-      ld part = ilerp(all[last_fail][0], all[last_fail+1][0], 0);
-      hyperpoint initial = normalize(lerp(all[last_fail], all[last_fail+1], 1 - (1-part) * .99));
-      bool have_initial = true;
-      v.push_back(glhr::pointtogl(initial));
-      last_fail++;
-      int at = last_fail;
-      do {
-        v.push_back(glhr::pointtogl(all[at]));
-        if(at == cnt-1 && all[at] != all[0]) {
-          p.cnt = isize(v); p.draw(); v.clear(); at = 0;
-          have_initial = false;
-          }
-        int next = at+1;
-        if(next == cnt) next = 0;
-        if(all[at][0] * all[next][0] <= 0 && (all[at][0] * all[next][zcoord] - all[next][0] * all[at][zcoord]) * (all[at][0] - all[next][0]) < 0) {
-          ld part = ilerp(all[at][0], all[next][0], 0);
-          if(part > .999 || part < .001) { in_broken = false; return; }
-          hyperpoint final = normalize(lerp(all[at], all[next], part * .99));
-          v.push_back(glhr::pointtogl(final));
-          if(have_initial) {
-            int max = 4 << vid.linequality;
-            if(final[0] * initial[0] > 0) {
-              for(int i=1; i<=max; i++)
-                v.push_back(glhr::pointtogl(lerp(final, initial, i * 1. / max)));
-              }
-            else {
-              hyperpoint end = Hypc;
-              end[ycoord] = final[ycoord] > 0 ? 1 : -1;
-              for(int i=1; i<=max; i++)
-                v.push_back(glhr::pointtogl(lerp(final, end, i * 1. / max)));
-              for(int i=1; i<=max; i++)
-                v.push_back(glhr::pointtogl(lerp(end, initial, i * 1. / max)));
-              }
-            }
-          p.cnt = isize(v); p.draw(); v.clear();
-          initial = normalize(lerp(all[at], all[next], 1 - (1-part) * .99));
-          have_initial = true;
-          v.push_back(glhr::pointtogl(initial));
-          }
-        at = next;
-        }
-      while(at != last_fail);
-      return;
-      }
-    }
+  if(broken_projection(*this)) return;  
   
   if(sphere && pmodel == mdTwoPoint && !in_twopoint) {
     #define MAX_PHASE 4