For body parts like knees and elbows to bend in a proper way, hinge connections should be used. A hinge connection acts as a pivot across which the limb would rotate. And for a hinge connection to work properly, the additional point controller should be placed on the bending axis.
To create a hinge connection:
1. Enable the Orthogonal to joint fold option.
2. Create rig elements for the limb.
3. Select additional point controllers before and after the place where the limb should bend.
4. Click the Union to hinge button.
The additional points you have selected will be positioned in one place. When the actual rig is generated, Cascadeur will interpret this as a marker for a hinge connection and create a hinge there.
Cascadeur can also automatically create a Direction Controller for the hinge.
This is only possible if the hinge is orthogonal to the edge that connect the main controller with the main direction controller.
Right (left) and non-right (right) angles
If the hinge is not orthogonal to the limb, you can fix this by using the Ortho hinge button:
1. Select both of the hinge controllers.
2. Click the Ortho hinge button
However, if the limbs of your characters are completely straight, the software would not be able to automatically calculate bending axes for them. In a case like this you’ll have to manually fold the limbs to the same degree.
To do this:
1. Select the Proto Component below the bending point.
2. Move it to the side a bit.
3. Select the Proto Component right after this one.
4. Move it in the opposite direction so the limb's overall configuration won't be distorted.
You'll see how the Direction and Main Controllers no longer align. You'll need to fix this:
5. Select the Main Controller.
6. Copy its position (via Edit menu or by pressing Ctrl + C).
7. Select the Direction Controller that should coincide with this Main Controller.
8. Paste (Ctrl + V) the Main Controller's position onto it.
9. Repest these steps for the other pair of controllers.
Finally, you'll need to re-establish the Hinge Connection:
10. Select both of the Additional Controllers that form the connection.
11. Click the Union to hinge button.
The connection will be created, but its position will shift.
12. Move the points using Manipulators.
13. Click the Straighten to hinge button.
Now, the limb should bend properly.
Hinges should be created for:
Creating a hinge connection also creates a direction controller for it. If you don't need it:
1. Select the proto component associated with the limb for which you create a hinge.
2. In the Outliner window, open the Proto union behavior tab:
3. On this tab, disable Create direction controller to hinge:
4. Now when you create a hinge connection for this joint, the program will not generate a direction controller for it.
Sometimes, the structure of the limb would imply several Hinge Connections in succession. For a case like this:
1. Select the rig elements for the next part of the limb.
2. Open the Proto Union Behavior tab in the Object Properties panel.
3. Enable the Is additional hinge option:
Make sure that the Additional Points are on the same side as the ones in the preceding hinge connection.
If they are not, you can select the point in the first hinge, copy its position (Ctrl + C) and then paste it (Ctrl + V) onto the Additional Point in the second connection.
Currently, you can only create two Hinge Connections in a row. A higher number of successive hinges won’t work properly.
This limitation will be removed in future versions.