# Train Assembly

Home >> Tutorials >> Train Assembly <<

In this video Rich imports both the rigged Engine and Hopper Car into the mine scene and then set up a rig to control the couplers between the trains and connect them to the track in the finished mine scene. After that is finished, he clones the Hopper Car to fill out the scene and then tests the controller to make sure the train is acting as it is expected to.

Users can jump ahead to a specific section by using the Chapter selection widget on the right side of the player or by directly clicking any of the Chapter Title links below.

Tab | Time | Chapter | Description
1 | 00:00:16 | Overview | Rig Sketch plan of how to assemble the train and hopper car together.
2 | 00:09:04 | Coupler Rig | Set-up Locators and add Constraints necessary to control the couplers between trains.
3 | 00:34:35 | Setup Logic | Adding the User Channels and Modifiers that control the cars position along the curve.
4 | 01:00:43 | Scene Prototype | Setup of multiple cars in a scene.
5 | 01:11:17 | Curve Resolve | Curve imprecision issue Rich spoke of in Engine tutorial rears its ugly head.
6 | 01:13:19 | Extract Curve | Making a curve from the tracks in the mine scene.
5 | 01:17:21 | Scene Assemble | Importing final rigged elements into the scene and attaching them to the extracted curve.
| 01:31:05 | Total Video Time |

Frequently Asked Questions--

Q.) Why did he choose not to rig the coupler completely, as in opening and closing?

> A.) Blame Kenneth Woodruff, one of his good buddies that gave him heat for over-doing everything and not getting things done. He held it over my head as a line I should not cross all Gandalf style. Its a good thing though, it means you are actually using this training instead of hearing me tease about it endlessly on the forums.

Q.) He mentioned that you could duplicate or "Instance" the Hopper Car, what is as Instance?

> A.) An Instance is like a duplicate but it contains no goemetry, instead, it just references the originating geometry. So if you were to make an instance of the Hopper Car and then make a model change to the original, that model change would be reflected in the Instance as well. A duplicate it just a copy with with no relationship to the original at all, so it would not adjust with any model change to the original. For more info check out the Duplicating and Instancing section in the Foundation.

Q.) Whoa, you can do math operations in the numeric entry fields?

> A.) You sure can. All the basic math operations are supported and also unit conversion. So if you were to input something in inches or feet modo would auto convert those values into meters (if that was the default unit you had set). Having math and unit conversion built right in is super helpful and a real time saver.

Q.) What is an "Up Vector"?

> A.) An Up Vector is a position in space that defines what "Up" is for things like Direction Constraints (and other modifiers). You can define a world axis or you can assign an actual item, which gives you a lot of flexibility. For more info check out the Constraints section in the Foundation.

Q.) Why do the properties for the scene keep showing up in the properties tab?

> A.) Whenever you click on a scene to move to it, which you will do often if you have more than one scene loaded, modo selected the scene "Item" and puts its channels into the properties tab. To remove these simply ctrl+click on the scene's name in the item list and they will go away.

Q.) Where did the initial geometry come from to allow the building of the Tracks curve?

> A.) That geometry was part of the Overview sections base scene. In the context of a studio environment, the layout artists and/or modeling department would have worked out the scene in this way allowing for the rigging group to base our controls on it.

Q.) He disconnects the mesh channels from all the path constraints in the Locomotive and Hopper Car scenes, why doesn't he just connect the mesh channel from the new curve into the mesh channels of the old curves to overwrite them?

> A.) That would be AWESOME, but modo doesn't allow for the mesh channels of a Mesh Item to be overwritten, they are read only. I have put in an official suggestion though, so we'll see if we get this in a future version.

Q.) When he pulls on the main control for the Locomotive the handle will move away from the train as it turns the corner, why?

> A.) This is a side effect of our Rig Control Item cheat, modo doesn't look at where this item is parented and adjust its manipulators to compensate, so it looks at where the item starts and sets it coordinate space relative to that. This means that to get the handle back to where it needs to be you will need to drop your tool and reactivate it. Its a bit of a bummer but the win out weighs the downside by a wide margin.

Resources--

Links to the modo in-line help system
Docs: Dynamic Parenting
Docs: Default Units (Accuracy and Units)
Docs: Direction Constraint
Docs: Up Vectors
Docs: Measure Distance Modifier
Docs: User Channels
Docs: Loop Slice
Docs: Merge Points

Links to other pages in this training
Training: Parenting and Hierarchies
Training: Constraints
Training: Transform Items
Training: Modifiers
Training: Channels
Training: Curves

File--

Links to the modo scenes used in the video
(click to open in modo)
File: Locomotive_07_Assemble_01.lxo
File: Locomotive_07_Assemble_02.lxo
File: HopperCar_06_Assemble_01.lxo
File: HopperCar_06_Assemble_02.lxo
File: AssemTrain_02_ProtoType_01.lxo
File: AssemTrain_02_ProtoType_02.lxo
File: AssemTrain_03_TrackBuilder_01.lxo
File: AssemTrain_03_TrackBuilder_02.lxo
File: AssemTrain_04_Assembly_01.lxo
File: AssemTrain_04_Assembly_02.lxo
File: AssemTrain_05_Complete_01.lxo

Top