From 8cf921a7420ad66de2e39ec429d2e6fcefe7625f Mon Sep 17 00:00:00 2001
From: Faith Ekstrand <faith.ekstrand@collabora.com>
Date: Mon, 3 Mar 2025 10:17:46 -0600
Subject: [PATCH] util/box: Add a intersect_2d helper

Fixes: 3d38c9597ff3 ("zink: hook up KHR_partial_update")
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33855>
---
 src/util/box.h | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/src/util/box.h b/src/util/box.h
index 53b00079b7f..2fb0be6fd23 100644
--- a/src/util/box.h
+++ b/src/util/box.h
@@ -190,6 +190,31 @@ u_box_union_2d(struct pipe_box *dst,
    dst->y = y;
 }
 
+/* Aliasing of @dst permitted. */
+static inline void
+u_box_intersect_2d(struct pipe_box *dst,
+                   const struct pipe_box *a, const struct pipe_box *b)
+{
+   int x, y;
+
+   x = MAX2(a->x, b->x);
+   y = MAX2(a->y, b->y);
+
+   dst->width = MIN2(a->x + a->width, b->x + b->width) - x;
+   dst->x = x;
+   if (dst->width <= 0) {
+      dst->x = 0;
+      dst->width = 0;
+   }
+
+   dst->height = MIN2(a->y + a->height, b->y + b->height) - y;
+   dst->y = y;
+   if (dst->height <= 0) {
+      dst->y = 0;
+      dst->height = 0;
+   }
+}
+
 /* Aliasing of @dst permitted. */
 static inline void
 u_box_union_3d(struct pipe_box *dst,