diff --git a/common/bspfile.cc b/common/bspfile.cc
index 73374f4c..2b0f1efb 100644
--- a/common/bspfile.cc
+++ b/common/bspfile.cc
@@ -54,14 +54,10 @@ struct gamedef_generic_t : public gamedef_t
 
     contentflags_t cluster_contents(const contentflags_t &, const contentflags_t &) const { throw std::bad_cast(); }
 
-    int32_t get_content_type(const contentflags_t &) const { throw std::bad_cast(); }
-
     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 uint16_t &) const { throw std::bad_cast(); }
-
     contentflags_t create_empty_contents(const uint16_t &) const { throw std::bad_cast(); }
 
     contentflags_t create_solid_contents(const uint16_t &) const { throw std::bad_cast(); }
@@ -76,6 +72,10 @@ struct gamedef_generic_t : public gamedef_t
 
     contentflags_t create_detail_solid_contents(const contentflags_t &original) const { throw std::bad_cast(); }
 
+    bool contents_are_type_equal(const contentflags_t &self, const contentflags_t &other) const { throw std::bad_cast(); }
+
+    bool contents_are_equal(const contentflags_t &self, const contentflags_t &other) const { throw std::bad_cast(); }
+
     bool contents_are_any_detail(const contentflags_t &) const { throw std::bad_cast(); }
 
     bool contents_are_detail_solid(const contentflags_t &contents) const { throw std::bad_cast(); }
@@ -85,9 +85,15 @@ struct gamedef_generic_t : public gamedef_t
     bool contents_are_detail_illusionary(const contentflags_t &contents) const { throw std::bad_cast(); }
 
     bool contents_are_empty(const contentflags_t &) const { throw std::bad_cast(); }
-
+    
     bool contents_are_mirrored(const contentflags_t &) const { throw std::bad_cast(); }
 
+    bool contents_are_origin(const contentflags_t &contents) const { throw std::bad_cast(); }
+
+    bool contents_are_clip(const contentflags_t &contents) const { throw std::bad_cast(); }
+
+    bool contents_clip_same_type(const contentflags_t &, const contentflags_t &) const { throw std::bad_cast(); }
+
     bool contents_are_solid(const contentflags_t &) const { throw std::bad_cast(); }
 
     bool contents_are_sky(const contentflags_t &) const { throw std::bad_cast(); }
@@ -116,6 +122,19 @@ struct gamedef_generic_t : public gamedef_t
     const std::vector<qvec3b> &get_default_palette() const { throw std::bad_cast(); };
 };
 
+// extra data for contentflags_t for Quake-like
+struct q1_contentflags_data
+{
+    bool origin = false; // is an origin brush
+
+    bool clip = false; // is a clip brush
+    
+    constexpr bool operator==(const q1_contentflags_data &other) const { return origin == other.origin && clip == other.clip; }
+    constexpr bool operator!=(const q1_contentflags_data &other) const { return !(*this == other); }
+
+    constexpr explicit operator bool() const { return origin || clip; }
+};
+
 template<gameid_t ID>
 struct gamedef_q1_like_t : public gamedef_t
 {
@@ -139,7 +158,7 @@ struct gamedef_q1_like_t : public gamedef_t
 
     contentflags_t cluster_contents(const contentflags_t &contents0, const contentflags_t &contents1) const
     {
-        if (contents0 == contents1)
+        if (contents0.equals(this, contents1))
             return contents0;
 
         /*
@@ -159,8 +178,6 @@ struct gamedef_q1_like_t : public gamedef_t
         return create_solid_contents();
     }
 
-    int32_t get_content_type(const contentflags_t &contents) const { return contents.native; }
-
     int32_t contents_priority(const contentflags_t &contents) const
     {
         if (contents.extended & CFLAGS_DETAIL) {
@@ -193,7 +210,7 @@ struct gamedef_q1_like_t : public gamedef_t
         return contents_are_solid(contents) || contents_are_sky(contents) || (contents.extended & CFLAGS_DETAIL);
     }
 
-    contentflags_t create_extended_contents(const uint16_t &cflags) const { return {0, cflags}; }
+    inline contentflags_t create_extended_contents(const q1_contentflags_data &data) const { return {0, 0, data}; }
 
     contentflags_t create_empty_contents(const uint16_t &cflags = 0) const
     {
@@ -236,6 +253,28 @@ struct gamedef_q1_like_t : public gamedef_t
         return {0, CFLAGS_DETAIL};
     }
 
+    bool contents_are_type_equal(const contentflags_t &self, const contentflags_t &other) const
+    {
+        if (self.game_data.has_value() != other.game_data.has_value()) {
+            return false;
+        }
+
+        if (self.game_data.has_value()) {
+            if (std::any_cast<const q1_contentflags_data &>(self.game_data) !=
+                std::any_cast<const q1_contentflags_data &>(other.game_data)) {
+                return false;
+            }
+        }
+
+        return (self.extended & CFLAGS_CONTENTS_MASK) == (other.extended & CFLAGS_CONTENTS_MASK) &&
+               self.native == other.native;
+    }
+
+    bool contents_are_equal(const contentflags_t &self, const contentflags_t &other) const
+    {
+        return contents_are_type_equal(self, other);
+    }
+
     bool contents_are_any_detail(const contentflags_t &contents) const
     {
         // in Q1, there are only CFLAGS_DETAIL, CFLAGS_DETAIL_ILLUSIONARY, or CFLAGS_DETAIL_FENCE
@@ -257,18 +296,11 @@ struct gamedef_q1_like_t : public gamedef_t
         return ((contents.extended & CFLAGS_DETAIL_ILLUSIONARY) != 0);
     }
 
-    bool contents_are_empty(const contentflags_t &contents) const
-    {
-        if (contents.extended & CFLAGS_CONTENTS_MASK)
-            return false;
-
-        return contents.native == CONTENTS_EMPTY;
-    }
-
     bool contents_are_mirrored(const contentflags_t &contents) const
     {
-        if (contents.extended & CFLAGS_BMODEL_MIRROR_INSIDE) {
-            return true;
+        // if we have mirrorinside set, go ahead
+        if (contents.mirror_inside.has_value()) {
+            return contents.mirror_inside.value();
         }
 
         // If the brush is non-solid, mirror faces for the inside view
@@ -277,10 +309,37 @@ struct gamedef_q1_like_t : public gamedef_t
                || (contents.native == CONTENTS_LAVA);
     }
 
+    bool contents_are_origin(const contentflags_t &contents) const
+    {
+        return contents.game_data.has_value() && std::any_cast<const q1_contentflags_data &>(contents.game_data).origin;
+    }
+
+    bool contents_are_clip(const contentflags_t &contents) const
+    {
+        return contents.game_data.has_value() && std::any_cast<const q1_contentflags_data &>(contents.game_data).clip;
+    }
+
+    bool contents_clip_same_type(const contentflags_t &self, const contentflags_t &other) const
+    {
+        return self.equals(this, other) && self.clips_same_type.value_or(true);
+    }
+
+    bool contents_are_empty(const contentflags_t &contents) const
+    {
+        if (contents.extended & CFLAGS_CONTENTS_MASK)
+            return false;
+        else if (contents.game_data.has_value() && std::any_cast<const q1_contentflags_data &>(contents.game_data))
+            return false;
+
+        return contents.native == CONTENTS_EMPTY;
+    }
+
     bool contents_are_solid(const contentflags_t &contents) const
     {
         if (contents.extended & CFLAGS_CONTENTS_MASK)
             return false;
+        else if (contents.game_data.has_value() && std::any_cast<const q1_contentflags_data &>(contents.game_data))
+            return false;
 
         return contents.native == CONTENTS_SOLID;
     }
@@ -289,6 +348,8 @@ struct gamedef_q1_like_t : public gamedef_t
     {
         if (contents.extended & CFLAGS_CONTENTS_MASK)
             return false;
+        else if (contents.game_data.has_value() && std::any_cast<const q1_contentflags_data &>(contents.game_data))
+            return false;
 
         return contents.native == CONTENTS_SKY;
     }
@@ -297,6 +358,8 @@ struct gamedef_q1_like_t : public gamedef_t
     {
         if (contents.extended & CFLAGS_CONTENTS_MASK)
             return false;
+        else if (contents.game_data.has_value() && std::any_cast<const q1_contentflags_data &>(contents.game_data))
+            return false;
 
         return contents.native <= CONTENTS_WATER && contents.native >= CONTENTS_LAVA;
     }
@@ -321,7 +384,7 @@ struct gamedef_q1_like_t : public gamedef_t
     bool portal_can_see_through(const contentflags_t &contents0, const contentflags_t &contents1) const
     {
         /* If contents values are the same and not solid, can see through */
-        return !(contents0.is_solid(this) || contents1.is_solid(this)) && contents0 == contents1;
+        return !(contents0.is_solid(this) || contents1.is_solid(this)) && contents0.equals(this, contents1);
     }
 
     bool contents_seals_map(const contentflags_t &contents) const override
@@ -367,11 +430,11 @@ struct gamedef_q1_like_t : public gamedef_t
     {
         // check for strong content indicators
         if (!Q_strcasecmp(texname.data(), "origin")) {
-            return create_extended_contents(CFLAGS_ORIGIN);
+            return create_extended_contents({ true, false });
         } else if (!Q_strcasecmp(texname.data(), "hint") || !Q_strcasecmp(texname.data(), "hintskip")) {
-            return create_extended_contents(CFLAGS_HINT);
+            return create_empty_contents();
         } else if (!Q_strcasecmp(texname.data(), "clip")) {
-            return create_extended_contents(CFLAGS_CLIP);
+            return create_extended_contents({ false, true });
         } else if (texname[0] == '*') {
             if (!Q_strncasecmp(texname.data() + 1, "lava", 4)) {
                 return create_liquid_contents(CONTENTS_LAVA);
@@ -382,10 +445,10 @@ struct gamedef_q1_like_t : public gamedef_t
             }
         } else if (!Q_strncasecmp(texname.data(), "sky", 3)) {
             return create_sky_contents();
-        } else {
-            // and anything else is assumed to be a regular solid.
-            return create_solid_contents();
         }
+
+        // and anything else is assumed to be a regular solid.
+        return create_solid_contents();
     }
 
     void init_filesystem(const fs::path &, const settings::common_settings &) const
@@ -543,8 +606,9 @@ struct gamedef_q2_t : public gamedef_t
         return c;
     }
 
-    int32_t get_content_type(const contentflags_t &contents) const
+    inline int32_t get_content_type(const contentflags_t &contents) const
     {
+        // fixme-brushbsp: should TRANSLUCENT be here? does it need to be?
         return contents.native & (Q2_ALL_VISIBLE_CONTENTS |
                                      (Q2_CONTENTS_PLAYERCLIP | Q2_CONTENTS_MONSTERCLIP | Q2_CONTENTS_ORIGIN |
                                          Q2_CONTENTS_TRANSLUCENT | Q2_CONTENTS_AREAPORTAL));
@@ -579,8 +643,6 @@ struct gamedef_q2_t : public gamedef_t
         return !!(contents.native & Q2_CONTENTS_SOLID);
     }
 
-    contentflags_t create_extended_contents(const uint16_t &cflags) const { return {0, cflags}; }
-
     contentflags_t create_empty_contents(const uint16_t &cflags) const { return {0, cflags}; }
 
     contentflags_t create_solid_contents(const uint16_t &cflags) const { return {Q2_CONTENTS_SOLID, cflags}; }
@@ -617,6 +679,18 @@ struct gamedef_q2_t : public gamedef_t
         return result;
     }
 
+    bool contents_are_type_equal(const contentflags_t &self, const contentflags_t &other) const
+    {
+        return (self.extended & CFLAGS_CONTENTS_MASK) == (other.extended & CFLAGS_CONTENTS_MASK) &&
+               get_content_type(self) == get_content_type(other);
+    }
+
+    bool contents_are_equal(const contentflags_t &self, const contentflags_t &other) const
+    {
+        return (self.extended & CFLAGS_CONTENTS_MASK) == (other.extended & CFLAGS_CONTENTS_MASK) &&
+               self.native == other.native;
+    }
+
     bool contents_are_any_detail(const contentflags_t &contents) const
     {
         return ((contents.native & Q2_CONTENTS_DETAIL) != 0);
@@ -652,24 +726,40 @@ struct gamedef_q2_t : public gamedef_t
             || ((contents.native & mist2_type) == mist2_type);
     }
 
+    bool contents_are_mirrored(const contentflags_t &contents) const
+    {
+        // if we have mirrorinside set, go ahead
+        if (contents.mirror_inside.has_value())
+            return contents.mirror_inside.value();
+
+        // Q2 is a bit different here. in vanilla tools,
+        // every content except SOLID is implicitly mirrorinside.
+        // the only exception is that 4bsp has the unused AUX
+        // contents to default to not mirroring the insides.
+        return !(contents.native & (Q2_CONTENTS_SOLID | Q2_CONTENTS_AUX));
+    }
+
+    bool contents_are_origin(const contentflags_t &contents) const
+    {
+        return contents.native & Q2_CONTENTS_ORIGIN;
+    }
+
+    bool contents_are_clip(const contentflags_t &contents) const
+    {
+        return contents.native & (Q2_CONTENTS_PLAYERCLIP | Q2_CONTENTS_MONSTERCLIP);
+    }
+    
+    bool contents_clip_same_type(const contentflags_t &self, const contentflags_t &other) const
+    {
+        return (self.native & Q2_ALL_VISIBLE_CONTENTS) == (other.native & Q2_ALL_VISIBLE_CONTENTS) && self.clips_same_type.value_or(true);
+    }
+
     bool contents_are_empty(const contentflags_t &contents) const
     {
         if (contents.extended & CFLAGS_CONTENTS_MASK)
             return false;
 
-        if (contents.native & Q2_CONTENTS_AREAPORTAL)
-            return false; // HACK: needs to return false in order for LinkConvexFaces to assign Q2_CONTENTS_AREAPORTAL
-                          // to the leaf
-
-        return !(contents.native & Q2_ALL_VISIBLE_CONTENTS);
-    }
-
-    bool contents_are_mirrored(const contentflags_t &contents) const
-    {
-        // fixme-brushbsp: support some way of opting out of mirrorinside
-
-        // If the brush is non-solid, mirror faces for the inside view
-        return !(contents.native & Q2_CONTENTS_SOLID);
+        return !get_content_type(contents);
     }
 
     bool contents_are_solid(const contentflags_t &contents) const
@@ -785,10 +875,8 @@ struct gamedef_q2_t : public gamedef_t
         const std::string &texname, const surfflags_t &flags, const contentflags_t &contents) const
     {
         // hints and skips are never detail, and have no content
-        if (flags.native & Q2_SURF_HINT) {
-            return {0, CFLAGS_HINT};
-        } else if (flags.native & Q2_SURF_SKIP) {
-            return {0, 0};
+        if (flags.native & (Q2_SURF_HINT | Q2_SURF_SKIP)) {
+            return {Q2_CONTENTS_EMPTY};
         }
 
         contentflags_t surf_contents = contents;
@@ -801,7 +889,7 @@ struct gamedef_q2_t : public gamedef_t
         // if we have TRANS33 or TRANS66, we have to be marked as WINDOW,
         // so unset SOLID, give us WINDOW, and give us TRANSLUCENT
         if (flags.native & (Q2_SURF_TRANS33 | Q2_SURF_TRANS66)) {
-            surf_contents.native |= Q2_CONTENTS_TRANSLUCENT | Q2_CONTENTS_DETAIL;
+            surf_contents.native |= Q2_CONTENTS_TRANSLUCENT;
 
             if (surf_contents.native & Q2_CONTENTS_SOLID) {
                 surf_contents.native = (surf_contents.native & ~Q2_CONTENTS_SOLID) | Q2_CONTENTS_WINDOW;
@@ -809,21 +897,16 @@ struct gamedef_q2_t : public gamedef_t
         }
 
         // translucent objects are automatically classified as detail
-        if (surf_contents.native & Q2_CONTENTS_WINDOW) {
+        if (surf_contents.native & Q2_CONTENTS_TRANSLUCENT) {
             surf_contents.native |= Q2_CONTENTS_DETAIL;
         } else if (surf_contents.native & (Q2_CONTENTS_MIST | Q2_CONTENTS_AUX)) {
             surf_contents.native |= Q2_CONTENTS_DETAIL;
         }
 
         if (surf_contents.native & (Q2_CONTENTS_MONSTERCLIP | Q2_CONTENTS_PLAYERCLIP)) {
-            surf_contents.extended |= CFLAGS_CLIP;
             surf_contents.native |= Q2_CONTENTS_DETAIL;
         }
 
-        if (surf_contents.native & Q2_CONTENTS_ORIGIN) {
-            surf_contents.extended |= CFLAGS_ORIGIN;
-        }
-
         return surf_contents;
     }
 
@@ -1105,10 +1188,16 @@ bool surfflags_t::is_valid(const gamedef_t *game) const
     return game->surfflags_are_valid(*this);
 }
 
+bool contentflags_t::equals(const gamedef_t *game, const contentflags_t &other) const
+{
+    return game->contents_are_equal(*this, other) &&
+        mirror_inside == other.mirror_inside &&
+        clips_same_type == other.clips_same_type;
+}
+
 bool contentflags_t::types_equal(const contentflags_t &other, const gamedef_t *game) const
 {
-    return (extended & CFLAGS_CONTENTS_MASK) == (other.extended & CFLAGS_CONTENTS_MASK) &&
-           game->get_content_type(*this) == game->get_content_type(other);
+    return game->contents_are_type_equal(*this, other);
 }
 
 int32_t contentflags_t::priority(const gamedef_t *game) const
@@ -1141,16 +1230,21 @@ bool contentflags_t::is_detail_illusionary(const gamedef_t *game) const
     return game->contents_are_detail_illusionary(*this);
 }
 
-bool contentflags_t::is_empty(const gamedef_t *game) const
-{
-    return game->contents_are_empty(*this);
-}
-
 bool contentflags_t::is_mirrored(const gamedef_t *game) const
 {
     return game->contents_are_mirrored(*this);
 }
 
+bool contentflags_t::will_clip_same_type(const gamedef_t *game, const contentflags_t &other) const
+{
+    return game->contents_clip_same_type(*this, other);
+}
+
+bool contentflags_t::is_empty(const gamedef_t *game) const
+{
+    return game->contents_are_empty(*this);
+}
+
 bool contentflags_t::is_solid(const gamedef_t *game) const
 {
     return game->contents_are_solid(*this);
@@ -1171,25 +1265,34 @@ bool contentflags_t::is_valid(const gamedef_t *game, bool strict) const
     return game->contents_are_valid(*this, strict);
 }
 
+bool contentflags_t::is_clip(const gamedef_t *game) const
+{
+    return game->contents_are_clip(*this);
+}
+
+bool contentflags_t::is_origin(const gamedef_t *game) const
+{
+    return game->contents_are_origin(*this);
+}
+
 std::string contentflags_t::to_string(const gamedef_t *game) const
 {
     std::string s = game->get_contents_display(*this);
 
-    if (extended & CFLAGS_BMODEL_MIRROR_INSIDE) {
-        s += "|BMODEL_MIRROR_INSIDE";
-    }
-    if (extended & CFLAGS_NO_CLIPPING_SAME_TYPE) {
-        s += "|NO_CLIPPING_SAME_TYPE";
-    }
-    if (extended & CFLAGS_HINT) {
-        s += "|HINT";
-    }
-    if (extended & CFLAGS_CLIP) {
+    // FIXME: how do we conditionally display this only when it matters (when it's not default basically)?
+    s += fmt::format("|MIRROR_INSIDE[{}]", mirror_inside.has_value() ? (clips_same_type.value() ? "true" : "false") : "nullopt");
+
+    s += fmt::format("|CLIPS_SAME_TYPE[{}]", clips_same_type.has_value() ? (clips_same_type.value() ? "true" : "false") : "nullopt");
+
+    // FIXME: duped for Q2, move to Q1?
+    if (is_clip(game)) {
         s += "|CLIP";
     }
-    if (extended & CFLAGS_ORIGIN) {
+    if (is_origin(game)) {
         s += "|ORIGIN";
     }
+    
+    // FIXME: duped for Q2, move to Q1?
     if (extended & CFLAGS_DETAIL) {
         s += "|DETAIL";
     }
diff --git a/include/common/bspfile.hh b/include/common/bspfile.hh
index a860973e..d14b6ace 100644
--- a/include/common/bspfile.hh
+++ b/include/common/bspfile.hh
@@ -25,6 +25,7 @@
 #include <variant>
 #include <vector>
 #include <unordered_map>
+#include <any>
 
 #include <common/cmdlib.hh>
 #include <common/log.hh>
@@ -523,6 +524,7 @@ enum q1_contents_t : int32_t
 // lower bits are stronger, and will eat weaker brushes completely
 enum q2_contents_t : int32_t
 {
+    Q2_CONTENTS_EMPTY = 0,
     Q2_CONTENTS_SOLID = nth_bit(0), // an eye is never valid in a solid
     Q2_CONTENTS_WINDOW = nth_bit(1), // translucent, but not watery
     Q2_CONTENTS_AUX = nth_bit(2),
@@ -563,12 +565,7 @@ enum q2_contents_t : int32_t
 // Special contents flags for the compiler only
 enum extended_cflags_t : uint16_t
 {
-    CFLAGS_BMODEL_MIRROR_INSIDE = nth_bit(3), /* set "_mirrorinside" "1" on a bmodel to mirror faces for when the player is inside. */
-    CFLAGS_NO_CLIPPING_SAME_TYPE = nth_bit(4), /* Don't clip the same content type. mostly intended for CONTENTS_DETAIL_ILLUSIONARY */
     // only one of these flags below should ever be set.
-    CFLAGS_HINT = nth_bit(5),
-    CFLAGS_CLIP = nth_bit(6),
-    CFLAGS_ORIGIN = nth_bit(7),
     CFLAGS_DETAIL = nth_bit(8),
     CFLAGS_DETAIL_ILLUSIONARY = nth_bit(9),
     CFLAGS_DETAIL_FENCE = nth_bit(10),
@@ -577,7 +574,7 @@ enum extended_cflags_t : uint16_t
     CFLAGS_DETAIL_MASK = (CFLAGS_DETAIL | CFLAGS_DETAIL_ILLUSIONARY | CFLAGS_DETAIL_FENCE),
     // all of the special content types
     CFLAGS_CONTENTS_MASK =
-        (CFLAGS_HINT | CFLAGS_CLIP | CFLAGS_ORIGIN | CFLAGS_DETAIL_MASK | CFLAGS_ILLUSIONARY_VISBLOCKER)
+        (CFLAGS_DETAIL_MASK | CFLAGS_ILLUSIONARY_VISBLOCKER)
 };
 
 struct gamedef_t;
@@ -590,25 +587,36 @@ struct contentflags_t
     // extra flags, specific to BSP only
     uint16_t extended;
 
-    constexpr bool operator==(const contentflags_t &other) const
-    {
-        return native == other.native && extended == other.extended;
-    }
+    // extra data supplied by the game
+    std::any game_data;
 
-    constexpr bool operator!=(const contentflags_t &other) const { return !(*this == other); }
+    // the value set directly from `_mirrorinside` on the brush, if available.
+    // don't check this directly, use `is_mirror_inside` to allow the game to decide.
+    std::optional<bool> mirror_inside = std::nullopt;
+
+    // Don't clip the same content type. mostly intended for CONTENTS_DETAIL_ILLUSIONARY.
+    // don't check this directly, use `will_clip_same_type` to allow the game to decide.
+    std::optional<bool> clips_same_type = std::nullopt;
+
+    bool equals(const gamedef_t *game, const contentflags_t &other) const;
 
     // is any kind of detail? (solid, liquid, etc.)
     bool is_any_detail(const gamedef_t *game) const;
     bool is_detail_solid(const gamedef_t *game) const;
     bool is_detail_fence(const gamedef_t *game) const;
     bool is_detail_illusionary(const gamedef_t *game) const;
+    
+    bool is_mirrored(const gamedef_t *game) const;
+    contentflags_t &set_mirrored(const std::optional<bool> &mirror_inside_value) { mirror_inside = mirror_inside_value; return *this; }
+    
+    inline bool will_clip_same_type(const gamedef_t *game) const { return will_clip_same_type(game, *this); }
+    bool will_clip_same_type(const gamedef_t *game, const contentflags_t &other) const;
+    contentflags_t &set_clips_same_type(const std::optional<bool> &clips_same_type_value) { clips_same_type = clips_same_type_value; return *this; }
 
     bool is_empty(const gamedef_t *game) const;
 
-    bool is_mirrored(const gamedef_t *game) const;
-
     // detail solid or structural solid
-    bool is_any_solid(const gamedef_t *game) const {
+    inline bool is_any_solid(const gamedef_t *game) const {
         return is_solid(game)
             || is_detail_solid(game);
     }
@@ -618,16 +626,10 @@ struct contentflags_t
     bool is_sky(const gamedef_t *game) const;
     bool is_liquid(const gamedef_t *game) const;
     bool is_valid(const gamedef_t *game, bool strict = true) const;
+    bool is_clip(const gamedef_t *game) const;
+    bool is_origin(const gamedef_t *game) const;
 
-    constexpr bool is_hint() const { return extended & CFLAGS_HINT; }
-
-    constexpr bool is_clip() const { return extended & CFLAGS_CLIP; }
-
-    constexpr bool is_origin() const { return extended & CFLAGS_ORIGIN; }
-
-    constexpr bool clips_same_type() const { return !(extended & CFLAGS_NO_CLIPPING_SAME_TYPE); }
-
-    bool is_fence(const gamedef_t *game) const {
+    inline bool is_fence(const gamedef_t *game) const {
         return is_detail_fence(game) || is_detail_illusionary(game);
     }
 
@@ -1801,10 +1803,8 @@ struct gamedef_t
     // FIXME: fix so that we don't have to pass a name here
     virtual bool texinfo_is_hintskip(const surfflags_t &flags, const std::string &name) const = 0;
     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 uint16_t &cflags = 0) const = 0;
     virtual contentflags_t create_empty_contents(const uint16_t &cflags = 0) const = 0;
     virtual contentflags_t create_solid_contents(const uint16_t &cflags = 0) const = 0;
     virtual contentflags_t create_sky_contents(const uint16_t &cflags = 0) const = 0;
@@ -1812,12 +1812,17 @@ struct gamedef_t
     virtual contentflags_t create_detail_illusionary_contents(const contentflags_t &original) const = 0;
     virtual contentflags_t create_detail_fence_contents(const contentflags_t &original) const = 0;
     virtual contentflags_t create_detail_solid_contents(const contentflags_t &original) const = 0;
+    virtual bool contents_are_type_equal(const contentflags_t &self, const contentflags_t &other) const = 0;
+    virtual bool contents_are_equal(const contentflags_t &self, const contentflags_t &other) const = 0;
     virtual bool contents_are_any_detail(const contentflags_t &contents) const = 0;
     virtual bool contents_are_detail_solid(const contentflags_t &contents) const = 0;
     virtual bool contents_are_detail_fence(const contentflags_t &contents) const = 0;
     virtual bool contents_are_detail_illusionary(const contentflags_t &contents) const = 0;
-    virtual bool contents_are_empty(const contentflags_t &contents) const = 0;
     virtual bool contents_are_mirrored(const contentflags_t &contents) const = 0;
+    virtual bool contents_are_origin(const contentflags_t &contents) const = 0;
+    virtual bool contents_are_clip(const contentflags_t &contents) const = 0;
+    virtual bool contents_are_empty(const contentflags_t &contents) const = 0;
+    virtual bool contents_clip_same_type(const contentflags_t &self, const contentflags_t &other) const = 0;
     virtual bool contents_are_solid(const contentflags_t &contents) const = 0;
     virtual bool contents_are_sky(const contentflags_t &contents) const = 0;
     virtual bool contents_are_liquid(const contentflags_t &contents) const = 0;
diff --git a/include/common/qvec.hh b/include/common/qvec.hh
index c0abd81e..1ed37b6c 100644
--- a/include/common/qvec.hh
+++ b/include/common/qvec.hh
@@ -1134,10 +1134,6 @@ struct twosided
 
     // swap the front and back values
     constexpr void swap() { std::swap(front, back); }
-
-    // equality checks
-    constexpr bool operator==(const twosided &other) const { return front == other.front && back == other.back; }
-    constexpr bool operator!=(const twosided &other) const { return !(*this == other); }
 };
 
 namespace qv {
diff --git a/qbsp/brush.cc b/qbsp/brush.cc
index feeebab4..aadfe8ca 100644
--- a/qbsp/brush.cc
+++ b/qbsp/brush.cc
@@ -333,6 +333,25 @@ void FixRotateOrigin(mapentity_t *entity)
 
     SetKeyValue(entity, "origin", qv::to_string(offset).c_str());
 }
+
+static bool Brush_IsHint(const hullbrush_t &brush)
+{
+    for (auto &f : brush.faces)
+        if (f.flags.is_hint)
+            return true;
+
+    return false;
+}
+
+static bool MapBrush_IsHint(const mapbrush_t &brush)
+{
+    for (size_t i = 0; i < brush.numfaces; i++)
+        if (brush.face(i).flags.is_hint)
+            return true;
+
+    return false;
+}
+
 /*
 =================
 CreateBrushFaces
@@ -354,7 +373,7 @@ static std::vector<face_t> CreateBrushFaces(const mapentity_t *src, hullbrush_t
     hullbrush->bounds = {};
 
     for (auto &mapface : hullbrush->faces) {
-        if (hullnum <= 0 && hullbrush->contents.is_hint()) {
+        if (hullnum <= 0 && Brush_IsHint(*hullbrush)) {
             /* Don't generate hintskip faces */
             const mtexinfo_t &texinfo = map.mtexinfos.at(mapface.texinfo);
 
@@ -802,7 +821,7 @@ static void Brush_LoadEntity(mapentity_t *dst, const mapentity_t *src, const int
     for (int i = 0; i < src->nummapbrushes; i++) {
         const mapbrush_t *mapbrush = &src->mapbrush(i);
         const contentflags_t contents = Brush_GetContents(mapbrush);
-        if (contents.is_origin()) {
+        if (contents.is_origin(options.target_game)) {
             if (dst == map.world_entity()) {
                 logging::print("WARNING: Ignoring origin brush in worldspawn\n");
                 continue;
@@ -859,10 +878,11 @@ static void Brush_LoadEntity(mapentity_t *dst, const mapentity_t *src, const int
 
     /* _mirrorinside key (for func_water etc.) */
     const bool mirrorinside_set = *ValueForKey(src, "_mirrorinside");
-    const bool all_mirrorinside = !!atoi(ValueForKey(src, "_mirrorinside"));
+    const std::optional<bool> mirrorinside = mirrorinside_set ? decltype(mirrorinside)(atoi(ValueForKey(src, "_mirrorinside")) ? true : false) : std::nullopt;
 
     /* _noclipfaces */
-    const bool noclipfaces = !!atoi(ValueForKey(src, "_noclipfaces"));
+    const bool noclipfaces_set = *ValueForKey(src, "_noclipfaces");
+    const std::optional<bool> clipsametype = noclipfaces_set ? decltype(clipsametype)(atoi(ValueForKey(src, "_noclipfaces")) ? false : true) : std::nullopt;
 
     const bool func_illusionary_visblocker = (0 == Q_strcasecmp(classname, "func_illusionary_visblocker"));
 
@@ -880,21 +900,14 @@ static void Brush_LoadEntity(mapentity_t *dst, const mapentity_t *src, const int
         bool detail = false;
         bool detail_illusionary = false;
         bool detail_fence = false;
-        bool mirrorinside = all_mirrorinside;
 
         // inherit the per-entity settings
         detail |= all_detail;
         detail_illusionary |= all_detail_illusionary;
         detail_fence |= all_detail_fence;
 
-        if (!mirrorinside_set) {
-            if (options.target_game->id == GAME_QUAKE_II && (contents.native & (Q2_CONTENTS_AUX | Q2_CONTENTS_MIST))) {
-                mirrorinside = true;
-            }
-        }
-
         /* "origin" brushes always discarded */
-        if (contents.is_origin())
+        if (contents.is_origin(options.target_game))
             continue;
 
         /* -omitdetail option omits all types of detail */
@@ -927,7 +940,7 @@ static void Brush_LoadEntity(mapentity_t *dst, const mapentity_t *src, const int
          * include them in the model bounds so collision detection works
          * correctly.
          */
-        if (contents.is_clip() && hullnum != HULL_COLLISION) {
+        if (hullnum != HULL_COLLISION && contents.is_clip(options.target_game)) {
             if (hullnum == 0) {
                 std::optional<brush_t> brush = LoadBrush(src, mapbrush, contents, rotate_offset, rottype, hullnum);
 
@@ -943,7 +956,7 @@ static void Brush_LoadEntity(mapentity_t *dst, const mapentity_t *src, const int
         }
 
         /* "hint" brushes don't affect the collision hulls */
-        if (contents.is_hint()) {
+        if (MapBrush_IsHint(*mapbrush)) {
             if (hullnum > 0)
                 continue;
             contents = options.target_game->create_empty_contents();
@@ -975,12 +988,8 @@ static void Brush_LoadEntity(mapentity_t *dst, const mapentity_t *src, const int
             contents = options.target_game->create_solid_contents();
 
         // apply extended flags
-        if (mirrorinside) {
-            contents.extended |= CFLAGS_BMODEL_MIRROR_INSIDE;
-        }
-        if (noclipfaces) {
-            contents.extended |= CFLAGS_NO_CLIPPING_SAME_TYPE;
-        }
+        contents.set_mirrored(mirrorinside);
+        contents.set_clips_same_type(clipsametype);
         if (func_illusionary_visblocker) {
             contents.extended |= CFLAGS_ILLUSIONARY_VISBLOCKER;
         }
diff --git a/qbsp/csg4.cc b/qbsp/csg4.cc
index 994e6baa..4ebec62a 100644
--- a/qbsp/csg4.cc
+++ b/qbsp/csg4.cc
@@ -262,7 +262,7 @@ static bool ShouldClipbrushEatBrush(const brush_t &brush, const brush_t &clipbru
     }
 
     if (clipbrush.contents.types_equal(brush.contents, options.target_game)) {
-        return clipbrush.contents.clips_same_type();
+        return clipbrush.contents.will_clip_same_type(options.target_game);
     }
 
     return false;
@@ -426,7 +426,7 @@ Returns a >= b as far as brush clipping
 bool BrushGE(const brush_t& a, const brush_t& b)
 {
     // same contents clip each other
-    if (a.contents == b.contents && a.contents.clips_same_type()) {
+    if (a.contents.will_clip_same_type(options.target_game, b.contents)) {
         // map file order
         return a.file_order > b.file_order;
     }
diff --git a/qbsp/exportobj.cc b/qbsp/exportobj.cc
index 1c3d594f..54eec22b 100644
--- a/qbsp/exportobj.cc
+++ b/qbsp/exportobj.cc
@@ -71,7 +71,8 @@ static void ExportObjFace(std::ofstream &f, const face_t *face, int *vertcount)
         // not sure why -v is needed, .obj uses (0, 0) in the top left apparently?
         fmt::print(f, "vt {:.9} {:.9}\n", uv[0], -uv[1]);
     }
-
+    
+    // fixme-brushbsp
     fmt::print(f, "usemtl contents{}_{}\n", face->contents[0].native, face->contents[0].extended);
     f << 'f';
     for (int i = 0; i < face->w.size(); i++) {
@@ -108,8 +109,9 @@ void ExportObj_Faces(const std::string &filesuffix, const std::vector<const face
     WriteContentsMaterial(mtlfile, {CONTENTS_LAVA}, 0.2, 0.0, 0.0);
 
     WriteContentsMaterial(mtlfile, {CONTENTS_SKY}, 0.8, 0.8, 1.0);
-    WriteContentsMaterial(mtlfile, {CONTENTS_SOLID, CFLAGS_CLIP}, 1, 0.8, 0.8);
-    WriteContentsMaterial(mtlfile, {CONTENTS_EMPTY, CFLAGS_HINT}, 1, 1, 1);
+    // fixme-brushbsp
+    //WriteContentsMaterial(mtlfile, {CONTENTS_SOLID, CFLAGS_CLIP}, 1, 0.8, 0.8);
+    //WriteContentsMaterial(mtlfile, {CONTENTS_EMPTY, CFLAGS_HINT}, 1, 1, 1);
 
     WriteContentsMaterial(mtlfile, {CONTENTS_SOLID, CFLAGS_DETAIL}, 0.5, 0.5, 0.5);
 
diff --git a/qbsp/merge.cc b/qbsp/merge.cc
index 2a5d4181..c045d37e 100644
--- a/qbsp/merge.cc
+++ b/qbsp/merge.cc
@@ -69,7 +69,8 @@ static face_t *TryMerge(face_t *f1, face_t *f2)
     bool keep1, keep2;
 
     if (!f1->w.size() || !f2->w.size() || f1->planeside != f2->planeside || f1->texinfo != f2->texinfo ||
-        f1->contents != f2->contents || f1->lmshift != f2->lmshift)
+        !f1->contents[0].equals(options.target_game, f2->contents[0]) || !f1->contents[1].equals(options.target_game, f2->contents[1]) || 
+        f1->lmshift[0] != f2->lmshift[0] || f1->lmshift[1] != f2->lmshift[1])
         return NULL;
 
     // find a common edge
diff --git a/qbsp/qbsp.cc b/qbsp/qbsp.cc
index 8f8025fc..13bf260a 100644
--- a/qbsp/qbsp.cc
+++ b/qbsp/qbsp.cc
@@ -998,7 +998,7 @@ static void BSPX_Brushes_AddModel(
             case CONTENTS_SLIME:
             case CONTENTS_LAVA:
             case CONTENTS_SKY:
-                if (b->contents.is_clip()) {
+                if (b->contents.is_clip(options.target_game)) {
                     perbrush.contents = -8;
                 } else {
                     perbrush.contents = b->contents.native;
@@ -1008,7 +1008,7 @@ static void BSPX_Brushes_AddModel(
             //                      perbrush.contents = -16;
             //                      break;
             default: {
-                if (b->contents.is_clip()) {
+                if (b->contents.is_clip(options.target_game)) {
                     perbrush.contents = -8;
                 } else {
                     logging::print("WARNING: Unknown contents: {}. Translating to solid.\n",
diff --git a/qbsp/surfaces.cc b/qbsp/surfaces.cc
index 50c26922..40861397 100644
--- a/qbsp/surfaces.cc
+++ b/qbsp/surfaces.cc
@@ -574,11 +574,11 @@ static std::list<face_t *> ClipFacesToTree_r(node_t *node, const brush_t *srcbru
             return {};
         }
 
-        // translucent contents also clip faces 
-        if (node->contents == srcbrush->contents 
-            && srcbrush->contents.clips_same_type()) {
+        // see what the game thinks about the clip
+        if (srcbrush->contents.will_clip_same_type(options.target_game, node->contents)) {
             return {};
         }
+
         // other content types let the faces thorugh
         return faces;
     }