X-Git-Url: https://git.jsancho.org/?p=gacela.git;a=blobdiff_plain;f=src%2Fsystem.scm;h=5a70cb5010e34f7db8c0905efd22cbc9b91794f3;hp=9654cffbafdb4a059aedfc3f3ef33fc58a10b1b2;hb=405b60cfd27f00e8dda02e19abe09bf7990bfbc2;hpb=8864bc71fcf9fd551bdb417a1b22655a9097dd30

diff --git a/src/system.scm b/src/system.scm
index 9654cff..5a70cb5 100644
--- a/src/system.scm
+++ b/src/system.scm
@@ -187,6 +187,11 @@
 
 ;;; Making systems
 
+(define-record-type entities-changes-type
+  (entities-changes changes)
+  entities-changes?
+  (changes get-entities-changes))
+
 (define* (find-entities-by-components c t)
   (cond ((null? t) '())
 	(else
@@ -213,7 +218,7 @@
 	   (lambda* (#:optional (entities2 #f) (components2 #f))
 	     (let ((e (if (and entities2 components2) entities2 entities))
 		   (c (if (and entities2 components2) components2 components)))
-	       (modify-entities res e c)))))))))
+	       (modify-entities (if (entities-changes? res) (get-entities-changes res) '()) e c)))))))))
 
 (define-syntax define-system
   (syntax-rules ()
@@ -274,7 +279,10 @@
 	(else
 	 (apply join-systems systems))))
 
-(export find-entities-by-components
+(export entities-changes
+	entities-changes?
+	get-entities-changes
+	find-entities-by-components
 	define-system
 	make-system
 	join-systems