Tomato Cycles: fix for vector pass gives wrong result in some circumstances

Issue was caused by wrong camera motion stored in device in cases
when first render layer does not have vector pass enabled.

Solved by forcing device camera update in cases when scene's motion
changed since previous device camera update.

intern/cycles/render/camera.cpp

@@ -75,6 +75,7 @@ Camera::Camera()
 
 	need_update = true;
 	need_device_update = true;
+	previous_motion = -1;
 }
 
 Camera::~Camera()
@@ -140,8 +141,19 @@ void Camera::update()
 
 void Camera::device_update(Device *device, DeviceScene *dscene, Scene *scene)
 {
+	Scene::MotionType need_motion = scene->need_motion();
+
 	update();
 
+	if (previous_motion != need_motion) {
+		/* scene's motion model could have been changed since
+		 * previous device camera update
+		 * this could happen for example in case when one render
+		 * layer has got motion pass and another not
+		 */
+		need_device_update = true;
+	}
+
 	if(!need_device_update)
 		return;
 	
@@ -159,7 +171,6 @@ void Camera::device_update(Device *device, DeviceScene *dscene, Scene *scene)
 	kcam->worldtocamera = transform_inverse(cameratoworld);
 
 	/* camera motion */
-	Scene::MotionType need_motion = scene->need_motion();
 	kcam->have_motion = 0;
 
 	if(need_motion == Scene::MOTION_PASS) {
@@ -226,6 +237,7 @@ void Camera::device_update(Device *device, DeviceScene *dscene, Scene *scene)
 	kcam->cliplength = (farclip == FLT_MAX)? FLT_MAX: farclip - nearclip;
 
 	need_device_update = false;
+	previous_motion = need_motion;
 }
 
 void Camera::device_free(Device *device, DeviceScene *dscene)

intern/cycles/render/camera.h

@@ -91,6 +91,7 @@ public:
 	/* update */
 	bool need_update;
 	bool need_device_update;
+	int previous_motion;
 
 	/* functions */
 	Camera();