From 13612f18d0c89a0b6601c292d761bc32cdc94877 Mon Sep 17 00:00:00 2001
From: Eric Wasylishen <ewasylishen@gmail.com>
Date: Sun, 1 May 2022 00:48:58 -0600
Subject: [PATCH] qbsp: factor out 'chops' condition in BrushGE

---
 common/bspfile.cc         | 18 ++++++++++++++++++
 include/common/bspfile.hh |  7 +++++++
 qbsp/csg4.cc              |  7 +------
 3 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/common/bspfile.cc b/common/bspfile.cc
index a794d9a5..d21da8f3 100644
--- a/common/bspfile.cc
+++ b/common/bspfile.cc
@@ -58,6 +58,8 @@ struct gamedef_generic_t : public gamedef_t
 
     int32_t contents_priority(const contentflags_t &) const { throw std::bad_cast(); }
 
+    bool chops(const contentflags_t &) const { throw std::bad_cast(); }
+
     contentflags_t create_extended_contents(const int32_t &) const { throw std::bad_cast(); }
 
     contentflags_t create_empty_contents(const int32_t &) const { throw std::bad_cast(); }
@@ -169,6 +171,10 @@ struct gamedef_q1_like_t : public gamedef_t
         }
     }
 
+    bool chops(const contentflags_t &contents) const { 
+        return contents_are_solid(contents) || contents_are_sky(contents) || (contents.extended & CFLAGS_DETAIL);
+    }
+
     contentflags_t create_extended_contents(const int32_t &cflags) const { return {0, cflags}; }
 
     contentflags_t create_empty_contents(const int32_t &cflags = 0) const
@@ -495,6 +501,13 @@ struct gamedef_q2_t : public gamedef_t
         }
     }
 
+    bool chops(const contentflags_t &contents) const
+    {
+        // TODO: ideally this could just check for Q2_CONTENTS_SOLID
+        // once we implement detail as Q2_CONTENTS_SOLID|Q2_CONTENTS_DETAIL
+        return contents_are_solid(contents) || (contents.extended & CFLAGS_DETAIL);
+    }
+
     contentflags_t create_extended_contents(const int32_t &cflags) const { return {0, cflags}; }
 
     contentflags_t create_empty_contents(const int32_t &cflags) const { return {0, cflags}; }
@@ -973,6 +986,11 @@ int32_t contentflags_t::priority(const gamedef_t *game) const
     return game->contents_priority(*this);
 }
 
+bool contentflags_t::chops(const gamedef_t* game) const
+{
+    return game->chops(*this);
+}
+
 bool contentflags_t::is_empty(const gamedef_t *game) const
 {
     return game->contents_are_empty(*this);
diff --git a/include/common/bspfile.hh b/include/common/bspfile.hh
index 56cacd1a..f8f73dcc 100644
--- a/include/common/bspfile.hh
+++ b/include/common/bspfile.hh
@@ -632,8 +632,14 @@ struct contentflags_t
     // also match.
     bool types_equal(const contentflags_t &other, const gamedef_t *game) const;
 
+    // when multiple brushes contribute to a leaf, the higher priority
+    // one determines the leaf contents
     int32_t priority(const gamedef_t *game) const;
 
+    // whether this should chop (if so, only lower priority content brushes get chopped)
+    // should return true only for solid / opaque content types
+    bool chops(const gamedef_t *game) const;
+
     std::string to_string(const gamedef_t *game) const;
 };
 
@@ -1767,6 +1773,7 @@ struct gamedef_t
     virtual contentflags_t cluster_contents(const contentflags_t &contents0, const contentflags_t &contents1) const = 0;
     virtual int32_t get_content_type(const contentflags_t &contents) const = 0;
     virtual int32_t contents_priority(const contentflags_t &contents) const = 0;
+    virtual bool chops(const contentflags_t &) const = 0;
     virtual contentflags_t create_extended_contents(const int32_t &cflags = 0) const = 0;
     virtual contentflags_t create_empty_contents(const int32_t &cflags = 0) const = 0;
     virtual contentflags_t create_solid_contents(const int32_t &cflags = 0) const = 0;
diff --git a/qbsp/csg4.cc b/qbsp/csg4.cc
index 3a9c413f..845b9977 100644
--- a/qbsp/csg4.cc
+++ b/qbsp/csg4.cc
@@ -527,12 +527,7 @@ static bool BrushGE(const brush_t& a, const brush_t& b)
 {
     // only chop if at least one of the two contents is
     // opaque (solid, sky, or detail)
-    if (!(a.contents.is_solid(options.target_game)
-          || b.contents.is_solid(options.target_game)
-          || a.contents.is_sky(options.target_game)
-          || b.contents.is_sky(options.target_game)
-          || a.contents.is_detail(CFLAGS_DETAIL)
-          || b.contents.is_detail(CFLAGS_DETAIL))) {
+    if (!(a.contents.chops(options.target_game) || b.contents.chops(options.target_game))) {
         return false;
     }