From 494c9e9e46d5600bc180211ac28f9a68118531e0 Mon Sep 17 00:00:00 2001
From: En Yi <en.yi@tutanota.com>
Date: Sun, 13 Aug 2023 12:34:27 +0800
Subject: [PATCH] Fix incorrect line test

By this project convention, the line extend will start from p1 and
end at p2, but not including p2 [p1, p2). Thus, existing tests are
testing a zero-length line, which should assert no collision.

Add test to properly test AABB edge collision with a line

Also update existing collision function to account for this
---
 CMakeLists.txt             | 2 +-
 scenes/engine/collisions.c | 2 +-
 tests/test_AABB.c          | 5 +++++
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index aab8df5..7582bb2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -111,7 +111,7 @@ target_link_libraries(assets_test
     ${GAME_LIBS}
 )
 
-if (UNIT_TESTING)
+if (BUILD_TESTING)
      find_package(cmocka 1.1.0 REQUIRED)
      add_subdirectory(tests)
 endif()
diff --git a/scenes/engine/collisions.c b/scenes/engine/collisions.c
index 820433b..6bef940 100644
--- a/scenes/engine/collisions.c
+++ b/scenes/engine/collisions.c
@@ -93,7 +93,7 @@ uint8_t check_collision_line(const CollideEntity_t* ent, TileGrid_t* grid, bool
     unsigned int tile_y2 = (ent->area.tile_y2 >= grid->height) ? grid->height - 1 : ent->area.tile_y2;
 
     Vector2 p1 = {ent->bbox.x, ent->bbox.y};
-    Vector2 p2 = {ent->bbox.x + ent->bbox.width - 1, ent->bbox.y + ent->bbox.height - 1};
+    Vector2 p2 = {ent->bbox.x + ent->bbox.width, ent->bbox.y + ent->bbox.height};
     for(unsigned int tile_y = tile_y1; tile_y <= tile_y2; tile_y++)
     {
         if (tile_y >= grid->height) return 0;
diff --git a/tests/test_AABB.c b/tests/test_AABB.c
index 3c0e391..35eda63 100644
--- a/tests/test_AABB.c
+++ b/tests/test_AABB.c
@@ -1,4 +1,5 @@
 #include "AABB.h"
+#include <stdio.h>
 
 #include <stdarg.h>
 #include <stddef.h>
@@ -25,10 +26,14 @@ static void test_line_AABB(void **state)
 
     p1.y = 0;
     p2.y = 0;
+    assert_false(line_in_AABB(p1, p2, box));
+    p2.y = 1;
     assert_true(line_in_AABB(p1, p2, box));
 
     p1 = (Vector2){5, 0};
     p2 = (Vector2){5, 10};
+    assert_false(line_in_AABB(p1, p2, box));
+    p2 = (Vector2){6, 10};
     assert_true(line_in_AABB(p1, p2, box));
 
     p1 = (Vector2){14, 0};