Game Development Reference
In-Depth Information
smoothing angles. This will increase the size of the resulting FBX file, but it's
ultimately worth it, if these elements need to be used and respected in your game
engine.
In Maya, it is a good practice to delete all construction history of objects in your
scene before exporting to FBX. This should provide the highest fidelity possible.
You can do so in Maya by simply selecting Delete All by Type in the Edit History
menu.
22.2.4 Objects and Transforms
Less Is faster.
Game assets should have as few separate elements as possible.
When constructing your final mesh, you should make sure to use as few textures
and materials as possible to improve eciency. Also try combining your meshes
together; the more separate nodes that exist in your object, the heavier the scene
becomes for the game engine and the renderer to process.
Orienting assets in the DCC.
The position of each game asset in your DCC should
be at (0
0), i.e., at the world origin, to avoid any potential problems with placing
the assets in your game environment.
Most DCCs follow a
,
0
,
y
-up world, in that the up axis for geometry created in the
application's world coordinates is the
y
-axis.
However, certain applications like 3ds Max use the
-axis as the world coordinate
system's up-axis. Since this up-axis cannot be changed in 3ds Max, you have the
option to convert the scene's world coordinate system upon exporting to FBX. By
default, the FBX exporter will convert the axis system to
z
y
-up, unless otherwise
specified.
Since most game engines are
-up as well, it's recommended to leave this setting
to its default value. When a scene is converted from
y
-up world coordinate
system, all scene root objects' pivots are rotated by 90 degrees in the negative
z
-up to a
y
x
-axis
or 270 degrees on the positive
-axis. All animation is affected by this conversion.
You will notice (for instance when exporting from 3ds Max to FBX) that scene
objects will import into Unity with a 270 degree rotation on the
x
-axis and all
rotation animation is resampled as a result of the up-axis conversion process.
Accordingly, if you have a scene to export that consists of several root objects, we
suggest that you parent a null or dummy object to all objects in the scene before
exporting to FBX in the
x
-up world coordinate system. This will add only one
rotation to the parent object of the scene and avoid animation re-sampling, while
all other child objects and their ancestors retain their original (0
y
,
0
,
0) rotation
values.
Maya allows the user to convert the up-axis system to a
z
-up axis world coor-
dinate system as well, but it is recommended to remain in the
-up world in Maya,
to avoid any axis conversion issues while exporting to FBX or importing into your
game engine.
y
