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/****************************************************************************
**
** Copyright (C) 1993-2009 NVIDIA Corporation.
** Copyright (C) 2020 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of Qt Design Studio.
**
** $QT_BEGIN_LICENSE:FDL$
** Commercial License Usage
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** accordance with the commercial license agreement provided with the
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** information use the contact form at https://www.qt.io/contact-us.
**
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** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of
** this file. Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
** $QT_END_LICENSE$
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****************************************************************************/
/*!
\contentspage index.html
\page exporting-3d-assets.html
\if defined(qtdesignstudio)
\previouspage qtbridge-sketch-using.html
\else
\previouspage studio-3d.html
\endif
\nextpage exporting-from-blender.html
\title Exporting 3D Assets
You can import files you created using 3D graphics applications and exported
to several widely-used formats, such as .blend, .dae, .fbx, .glb, .gltf,
.obj, .uia, or .uip. For a list of formats supported by each \l{Qt Quick 3D}
version, see the module documentation.
Depending on the 3D graphics tool, you might need to install export plugins
to be able to export files to a particular format.
To get the best results when exporting 3D assets and importing them to
\QDS, follow the general guidelines in the following sections. For more
information about using the export plugins for a particular tool, see
\l{Exporting from Different Tools}.
\section1 Geometry
\QDS supports geometry exported as triangles, quads, and pentagons. For
basic geometry, you mostly need to pay attention to pivot points and
transformation.
\section2 Pivot Points
In \QDS, there is only one pivot per component. It is used as the origin
for scaling and rotation. Adjust the position of a 3D model's pivot as
needed.
However, extreme edits to pivots in 3D modeling tools can cause problems
when importing to \QDS, especially if animated. This difference is often
manifested as a difference in the position or orientation of a component.
You can prevent these kinds of problems by only making simple edits to
your pivot points. Keep your pivot points to the default (world) alignment,
don't scale them, and make sure that if you have multiple pivots (Maya)
that they are all at the same location in space.
\section2 Transformation
You can import full 3D transform information including position, rotation,
scale, and pivot. \QDS can import left and right-handed coordinate systems,
y-up or z-up, and rotations applied in any order. The principal limitation
in this area are pivot points. As discussed above, only simple edits to
pivot points are supported.
Most 3D graphics tools enable you to apply transformation to components and
vertices. We highly recommend doing so before importing mesh data into \QDS.
This ensures that the mesh coming into \QDS has clean transform data and no
arbitrary transform values which can be confusing or an impediment to your
work.
\note After applying transformations, you may have to reposition the pivot
point in some 3D graphics tools.
\section1 Animations
Animations are supported on any imported property. Position, rotation,
scale, and pivot can all be animated. For example, a hierarchy of items,
rotated simultaneously on arbitrary axes in arbitrary axis order can be
imported. \QDS also supports importing bezier tangent value tweaked into
animations.
\section2 Time-based Animations
In many 3D modeling tools, when you create keyframes you associate them with
frame numbers. This is great in the film industry where frame rates are
constant, but poses problems in applications where the frame rate may or
may not be rock solid. If you were to specify that the logo animation will
play for 180 frames, it might play for 3 seconds at 60 FPS, but if the speed
drops to 30 fps, the animation will also get much slower.
Luckily, accounting for this is relatively simple. Many 3D modeling tools
default to a setting of 24 frames per second, so your keyframes will
be translated at that ratio. If you want a keyframe at one second, put
it on frame 24. For two seconds, use frame 48, and so on.
Usually, configurable frame rates are offered, and the frame rate setting
should be respected upon import.
Some tools, such as Maya, start at frame 1, by default. If you have a
keyframe at frame 1, the time for that keyframe will be 1/24, or 0.041
seconds. Edit your Maya animation settings to start your animations at
frame 0, or 0/24 = 0 seconds.
In \QDS, you can specify the duration of the animation in addition to its
start and end frame.
\section2 Deform Animations
\e {Deform animations}, such as lattice and bend, are not supported by \QDS.
However, you can work around this limitation by converting deform animations
into \e {blend shape} animations that are supported in FBX format. Before
exporting the animations, you need to bake the actions in them into key
frames.
\section2 Baking Actions for Animations
You need to bake actions to export animations that are using custom curves
or object constraints to control the animation.
\e Actions are data-blocks containing animation data. If you are exporting
animations, you need to bake actions.
\section2 Animation Systems
3D modeling tools offer highly complex and specialized animation systems.
We recommend using the \QDS \uicontrol Timeline view whenever practical.
This helps keep mesh information on import clean and reduces conflicts
between imported mesh animation and \QDS's animation.
The animation system in \QDS is a full implementation of bezier
keys, and the full complement of bezier animation that you can create
with 3D modeling tools and export are represented in \QDS. The more
extreme differences between the various animation systems are mitigated
by the limitations imposed by the supported formats.
\section1 Materials and Textures
Create and assign material slots in the 3D graphics tool before you export
3D graphics. If you add several material slots, the first one is assigned
to the object. Only material slots that have a material and that are
assigned to a mesh on the exported object are imported into \QDS.
If no material slots are assigned to an object, a default material is
attached to the component that is created when you import the assets to
\QDS.
UV-unwrapping your model will create a UV layout. Without a UV layout, you
will not be able to render any textures on your model in \QDS.
There are many different ways and techniques to unwrap 3D meshes, depending
on the 3D graphics tool.
\section1 Lights
Lights are imported to \QDS. Position, rotation, scale, brightness,
light color, and the cast shadows property values are preserved.
If the light type is not supported by Qt Quick 3D, it is converted into
one of the supported types.
\section1 Cameras
Perspective and orthographic cameras are imported to \QDS. Position,
rotation, and scale property values, as well as start and end clipping
values are preserved. For perspective cameras, field of view values
are also preserved.
\section1 Node Hierarchy
\QDS supports importing hierarchical information. Hierarchies of arbitrary
depth are supported, including grouped nodes. Hierarchical transforms are
applied as expected.
\section1 Exporting from Different Tools
The following sections provide additional information about exporting
3D assets from a particular tool:
\list
\li \l{Exporting from Blender}{Blender}
\li \l{Exporting from Maya}{Maya}
\endlist
*/
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