From a81441b1e98f21f537a9709a2b640b2826a712d2 Mon Sep 17 00:00:00 2001
From: Marty <85036874+MatusGuy@users.noreply.github.com>
Date: Mon, 18 Sep 2023 20:50:21 +0100
Subject: [PATCH] Raycast function returns what it hit (#2631)

- Raycast function that returns what raycast hit
- Fix random segfault?
- Use union for hit
---
 src/collision/collision_system.cpp | 46 ++++++++++++++++++++++++------
 src/collision/collision_system.hpp | 18 ++++++++++++
 2 files changed, 55 insertions(+), 9 deletions(-)

diff --git a/src/collision/collision_system.cpp b/src/collision/collision_system.cpp
index 35afbbf74cf..7a5dedd11c4 100644
--- a/src/collision/collision_system.cpp
+++ b/src/collision/collision_system.cpp
@@ -690,10 +690,14 @@ CollisionSystem::is_free_of_movingstatics(const Rectf& rect, const CollisionObje
   return true;
 }
 
-bool
-CollisionSystem::free_line_of_sight(const Vector& line_start, const Vector& line_end, bool ignore_objects, const CollisionObject* ignore_object) const
+CollisionSystem::RaycastResult
+CollisionSystem::get_first_line_intersection(const Vector& line_start,
+                                             const Vector& line_end,
+                                             bool ignore_objects,
+                                             const CollisionObject* ignore_object) const
 {
   using namespace collision;
+  RaycastResult result{};
 
   // Check if no tile is in the way.
   const float lsx = std::min(line_start.x, line_end.x);
@@ -709,16 +713,26 @@ CollisionSystem::free_line_of_sight(const Vector& line_start, const Vector& line
         {
           continue;
         }
-        
-        const Tile& tile = solids->get_tile_at(test_vector);
+
+        const Tile* tile = &solids->get_tile_at(test_vector);
+
         // FIXME: check collision with slope tiles
-        if ((tile.get_attributes() & Tile::SOLID)) return false;
+        if ((tile->get_attributes() & Tile::SOLID))
+        {
+          result.is_valid = true;
+          result.hit.tile = tile;
+          result.box = {glm::floor((test_vector - solids->get_offset()) / 32.0f), Sizef(32.f, 32.f)};
+          return result;
+        }
       }
     }
   }
 
   if (ignore_objects)
-    return true;
+  {
+    result.is_valid = false;
+    return result;
+  }
 
   // Check if no object is in the way.
   for (const auto& object : m_objects) {
@@ -726,12 +740,26 @@ CollisionSystem::free_line_of_sight(const Vector& line_start, const Vector& line
     if (!object->is_valid()) continue;
     if ((object->get_group() == COLGROUP_MOVING)
         || (object->get_group() == COLGROUP_MOVING_STATIC)
-        || (object->get_group() == COLGROUP_STATIC)) {
-      if (intersects_line(object->get_bbox(), line_start, line_end)) return false;
+        || (object->get_group() == COLGROUP_STATIC))
+    {
+      if (intersects_line(object->get_bbox(), line_start, line_end))
+      {
+        result.is_valid = true;
+        result.hit.object = object;
+        result.box = object->get_bbox();
+        return result;
+      }
     }
   }
 
-  return true;
+  result.is_valid = false;
+  return result;
+}
+
+bool
+CollisionSystem::free_line_of_sight(const Vector& line_start, const Vector& line_end, bool ignore_objects, const CollisionObject* ignore_object) const
+{
+  return !get_first_line_intersection(line_start, line_end, ignore_objects, ignore_object).is_valid;
 }
 
 std::vector<CollisionObject*>
diff --git a/src/collision/collision_system.hpp b/src/collision/collision_system.hpp
index c422f9755ab..a263e439d3c 100644
--- a/src/collision/collision_system.hpp
+++ b/src/collision/collision_system.hpp
@@ -34,6 +34,18 @@ class Sector;
 
 class CollisionSystem final
 {
+public:
+  struct RaycastResult
+  {
+    bool is_valid; /**< true if raycast hit something */
+    union
+    {
+      const CollisionObject* object;
+      const Tile* tile;
+    } hit; /**< tile/object that the raycast hit */
+    Rectf box = {}; /**< hitbox of tile/object */
+  };
+
 public:
   CollisionSystem(Sector& sector);
 
@@ -56,6 +68,12 @@ class CollisionSystem final
   bool is_free_of_tiles(const Rectf& rect, const bool ignoreUnisolid = false, uint32_t tiletype = Tile::SOLID) const;
   bool is_free_of_statics(const Rectf& rect, const CollisionObject* ignore_object, const bool ignoreUnisolid) const;
   bool is_free_of_movingstatics(const Rectf& rect, const CollisionObject* ignore_object) const;
+
+
+  RaycastResult get_first_line_intersection(const Vector& line_start,
+                                            const Vector& line_end,
+                                            bool ignore_objects,
+                                            const CollisionObject* ignore_object) const;
   bool free_line_of_sight(const Vector& line_start, const Vector& line_end, bool ignore_objects, const CollisionObject* ignore_object) const;
 
   std::vector<CollisionObject*> get_nearby_objects(const Vector& center, float max_distance) const;