add collision intersection function from raylib

3 files changed, 38 insertions, 0 deletions

diff --git a/include/rodeo.h b/include/rodeo.h
index c49bd5e..a9dae49 100644
--- a/include/rodeo.h
+++ b/include/rodeo.h
@@ -6,6 +6,7 @@
 #include "rodeo/log.h"
 #include "rodeo/common.h"
 #include "rodeo/audio.h"
+#include "rodeo/collision.h"
 
 // -- external --
 #include "stc/cstr.h"
diff --git a/include/rodeo/collision.h b/include/rodeo/collision.h
index 277b780..365522c 100644
--- a/include/rodeo/collision.h
+++ b/include/rodeo/collision.h
@@ -2,6 +2,7 @@
 // -- internal --
 // public
 #include "rodeo/collision_t.h"
+#include "rodeo_types.h"
 
 rodeo_collision_2d_world_t
 rodeo_collision_2d_world_create(void);
@@ -50,3 +51,10 @@ rodeo_collision_2d_world_compare_other(
 		rodeo_collision_2d_world_item_t *b
 	)
 );
+
+// from raylib GetCollisionRect
+rodeo_rectangle_t
+rodeo_collision_2d_get_collision_rect(
+    rodeo_collision_2d_world_item_t *a,
+    rodeo_collision_2d_world_item_t *b
+);
diff --git a/src/collision/rodeo_collision.c b/src/collision/rodeo_collision.c
index de2f9a3..b2a7388 100644
--- a/src/collision/rodeo_collision.c
+++ b/src/collision/rodeo_collision.c
@@ -122,3 +122,32 @@ int rodeo_collision_2d_item_cmp(
 		return a->id.id > b->id.id ? 1 : -1;
 	}
 }
+
+// from raylib GetCollisionRect
+rodeo_rectangle_t
+rodeo_collision_2d_get_collision_rect(
+    rodeo_collision_2d_world_item_t *a,
+    rodeo_collision_2d_world_item_t *b
+)
+{
+	rodeo_rectangle_t overlap = { 0 };
+
+    float left = (a->x > b->x)? a->x : b->x;
+    float right1 = a->x + a->width;
+    float right2 = b->x + b->width;
+    float right = (right1 < right2)? right1 : right2;
+    float top = (a->y > b->y)? a->y : b->y;
+    float bottom1 = a->y + a->height;
+    float bottom2 = b->y + b->height;
+    float bottom = (bottom1 < bottom2)? bottom1 : bottom2;
+
+    if ((left < right) && (top < bottom))
+    {
+        overlap.x = left;
+        overlap.y = top;
+        overlap.width = right - left;
+        overlap.height = bottom - top;
+    }
+
+    return overlap;
+}