Fix #31556: cycles object info random value was not properly randomized for

dupligroups.

3 files changed, 9 insertions, 8 deletions

diff --git a/intern/cycles/blender/blender_object.cpp b/intern/cycles/blender/blender_object.cpp
index 14d4c2f3ddf..b04e0137e37 100644
--- a/intern/cycles/blender/blender_object.cpp
+++ b/intern/cycles/blender/blender_object.cpp
@@ -29,6 +29,7 @@
 #include "blender_util.h"
 
 #include "util_foreach.h"
+#include "util_hash.h"
 
 CCL_NAMESPACE_BEGIN
 
@@ -245,17 +246,20 @@ void BlenderSync::sync_object(BL::Object b_parent, int b_index, BL::Object b_ob,
 	/* object sync */
 	if(object_updated || (object->mesh && object->mesh->need_update)) {
 		object->name = b_ob.name().c_str();
-		object->instance_id = b_index;
 		object->pass_id = b_ob.pass_index();
 		object->tfm = tfm;
 		object->motion.pre = tfm;
 		object->motion.post = tfm;
 		object->use_motion = false;
 
+		object->random_id = hash_int_2d(hash_string(object->name.c_str()), b_index);
+
 		/* visibility flags for both parent */
 		object->visibility = object_ray_visibility(b_ob) & PATH_RAY_ALL;
-		if(b_parent.ptr.data != b_ob.ptr.data)
+		if(b_parent.ptr.data != b_ob.ptr.data) {
 			object->visibility &= object_ray_visibility(b_parent);
+			object->random_id ^= hash_int(hash_string(b_parent.name().c_str()));
+		}
 
 		/* camera flag is not actually used, instead is tested
 		   against render layer flags */
diff --git a/intern/cycles/render/object.cpp b/intern/cycles/render/object.cpp
index e38b2635f90..5c7e48a38eb 100644
--- a/intern/cycles/render/object.cpp
+++ b/intern/cycles/render/object.cpp
@@ -23,7 +23,6 @@
 #include "scene.h"
 
 #include "util_foreach.h"
-#include "util_hash.h"
 #include "util_map.h"
 #include "util_progress.h"
 
@@ -37,7 +36,7 @@ Object::Object()
 	mesh = NULL;
 	tfm = transform_identity();
 	visibility = ~0;
-	instance_id = 0;
+	random_id = 0;
 	pass_id = 0;
 	bounds = BoundBox::empty;
 	motion.pre = transform_identity();
@@ -165,9 +164,7 @@ void ObjectManager::device_update_transforms(Device *device, DeviceScene *dscene
 		float uniform_scale;
 		float surface_area = 0.0f;
 		float pass_id = ob->pass_id;
-		
-		uint ob_hash = hash_int_2d(hash_string(ob->name.c_str()), ob->instance_id);
-		float random_number = (float)ob_hash * (1.0f/(float)0xFFFFFFFF);
+		float random_number = (float)ob->random_id * (1.0f/(float)0xFFFFFFFF);
 		
 		if(transform_uniform_scale(tfm, uniform_scale)) {
 			map<Mesh*, float>::iterator it = surface_area_map.find(mesh);
diff --git a/intern/cycles/render/object.h b/intern/cycles/render/object.h
index b8169e3758e..83bf2cf0317 100644
--- a/intern/cycles/render/object.h
+++ b/intern/cycles/render/object.h
@@ -41,7 +41,7 @@ public:
 	Transform tfm;
 	BoundBox bounds;
 	ustring name;
-	int instance_id;
+	int random_id;
 	int pass_id;
 	vector<ParamValue> attributes;
 	uint visibility;