1 files changed, 27 insertions, 0 deletions
diff --git a/src/stage.c b/src/stage.c
index 10a7f0a..a2c6e2d 100644
--- a/src/stage.c
+++ b/src/stage.c
@@ -310,3 +310,30 @@ stage_t * stage_lookup_name(stage_t *stage, const char *name)
 
 	return NULL;
 }
+
+
+/* lookup a stage by an opaque key using the per-stage match_func when present,
+ * returns first match, does not support multiple matches.
+ * Intended for rudimentary non-overlapping spatial searches like picking of
+ * basic 2D UI elements.
+ */
+stage_t * stage_lookup_key(stage_t *stage, void *key)
+{
+	assert(stage);
+
+	if (stage->match && stage->match(stage, stage->object, key))
+		return stage;
+
+	for (int i = 0; i < STAGE_LAYERS_MAX; i++) {
+		stage_t	*s;
+
+		DLL_FOR_EACH_ENTRY(&stage->layers[i], s, stage_t, layer) {
+			stage_t	*match = stage_lookup_key(s, key);
+
+			if (match)
+				return match;
+		}
+	}
+
+	return NULL;
+}