diff --git a/core/src/shape.c b/core/src/shape.c
index 52bc5d1..7dee5f2 100644
--- a/core/src/shape.c
+++ b/core/src/shape.c
@@ -11,6 +11,7 @@ struct Shape {
 
     Vector mean;
     int is_convex;
+    Vector min, max;
 };
 
 static
@@ -40,7 +41,7 @@ int _shape_calculate_is_convex(Shape* self) {
     // point relative to mean
     Vector relative;
     list_foreach(Vector*, point, &self->points) {
-        relative = vsubf(*point, self->mean);
+        relative = vnormalizedf(vsubf(*point, self->mean));
         if(point != _shape_get_furthest_in_direction(self, relative)) {
             return 0;
         }
@@ -183,3 +184,29 @@ void shape_draw(Shape* self, Transform transform) {
         SDL_RenderDrawLineF(g_renderer, lhs.x, lhs.y, rhs.x, rhs.y);
     }
 }
+
+Vector shape_get_min_extent(Shape* self, Transform* transform) {
+    if(self->points.len == 0)
+        return ZeroVector;
+    Vector min = *list_at_as(Vector, &self->points, 0);
+    Vector point;
+    for(size_t i = 0; i < shape_get_points_count(self); ++i) {
+        point = shape_get_point_transformed(self, i, *transform);
+        min.x = fminf(min.x, point.x);
+        min.y = fminf(min.y, point.y);
+    }
+    return min;
+}
+
+Vector shape_get_max_extent(Shape* self, Transform* transform) {
+    if(self->points.len == 0)
+        return ZeroVector;
+    Vector max = *list_at_as(Vector, &self->points, 0);
+    Vector point;
+    for(size_t i = 0; i < shape_get_points_count(self); ++i) {
+        point = shape_get_point_transformed(self, i, *transform);
+        max.x = fmaxf(max.x, point.x);
+        max.y = fmaxf(max.y, point.y);
+    }
+    return max;
+}
diff --git a/core/src/shape.h b/core/src/shape.h
index 650ab82..ee4bf9c 100644
--- a/core/src/shape.h
+++ b/core/src/shape.h
@@ -29,4 +29,7 @@ extern Vector shape_get_median_point(Shape* self);
 extern int shape_is_convex(Shape* self);
 extern void shape_draw(Shape* self, Transform transform);
 
+extern Vector shape_get_min_extent(Shape* self, Transform* transform);
+extern Vector shape_get_max_extent(Shape* self, Transform* transform);
+
 #endif // !_fencer_shape_h