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// Copyright (C) 2020 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
/*!
\page studio-3d-scene-environment.html
\previouspage studio-3d-camera.html
\nextpage studio-3d-morph-target.html
\title Scene Environment
You can use the \uicontrol {Scene Environment} component to specify
how a scene is rendered globally. You can specify settings for antialiasing,
scene background, ambient occlusion, and image-based lighting in the
\l Properties view. The \uicontrol {Scene Environment} component is available
in \uicontrol Components > \uicontrol {Qt Quick 3D}. It is
automatically included under the 3D view component in \l{Creating Projects}
{projects created} using the \uicontrol {Qt Quick 3D Application} wizard
template.
\note If you select \uicontrol {Qt 5} as the \uicontrol {Target Qt Version}
when \l {Creating Projects}{creating your project}, the available properties
for this component will be slightly different. The properties may also be
situated differently in the \uicontrol Properties view.
\section1 Setting the Scene Environment
In the \uicontrol {Scene Environment} section of the \uicontrol Properties
view, you can specify whether and how the background of the scene should be
cleared, specify whether you wish to perform depth-tests on the scene,
apply post-processing effects to the scene, and define how colors are
tonemapped before the scene is rendered.
\image studio-3d-scene-environment-properties.png "The Scene Environment properties"
The \uicontrol {Clear color} property specifies which color will be used to
clear the background of the scene if \uicontrol {Background mode} is defined
as \uicontrol Color. Use the \l{Picking Colors}{color picker} to select the
color of your choice.
The \uicontrol {Background mode} property defines whether the background
of the scene should be cleared as well as the manner of clearing it.
Use the dropdown menu to select one of the available modes:
\table
\header
\li Background Mode
\li Description
\row
\li Transparent
\li The scene is cleared to be transparent, which is useful
for rendering 3D content on top of another item. This mode
has no effect when the \uicontrol View3D component is using
\uicontrol Underlay or \uicontrol Overlay as the render mode.
\row
\li Color
\li The scene is cleared with the color specified by the
\uicontrol {Clear color} property. This mode has no effect
when the \uicontrol View3D component is using the
\uicontrol Underlay or \uicontrol Overlay as the render
mode.
\row
\li SkyBox
\li The scene will not be cleared, but instead a
\uicontrol SkyBox or Skydome will be rendered. Define an
image as a \uicontrol SkyBox using the
\uicontrol Image property in the \uicontrol {Light probe}
section (In Qt 5, the \uicontrol {Light Probe} property in
the \uicontrol {Image-Based Lighting} group.
\endtable
To leave the scene uncleared, select \uicontrol {Unspecified} as the
\uicontrol {Background mode}.
You can perform depth tests to optimize the scene environment. To skip the
depth tests, deselect the \uicontrol {Enable depth test} checkbox. Note that
skipping the tests can cause rendering errors.
To have the renderer write to the depth buffer as part of the color pass,
deselect the \uicontrol {Enable depth prepass} checkbox. Deselecting the
checkbox disables the depth prepass on any GPU that uses tiled rendering
architecture.
The \uicontrol Effect property defines a post-processing effect to the
scene. Use the dropdown menu to select one of the effects that will be
applied to the entire scene. The order of the effects is significant since
the result of each effect is fed to the next.
The \uicontrol {Tonemap mode} property defines how colors are tonemapped
before rendering. Select \uicontrol ToneMapModeLinear to apply linear
tonemapping, which gamma corrects colors and returns them in sRGB color
space. You can also select \uicontrol ToneMapModeAces to apply Academy Color
Encoding System, \uicontrol ToneMapModeHejlDawson to apply the Hejl-Dawson
tonemapping, or \uicontrol ToneMapModeFilmic to apply filmic tonemapping.
\note The \uicontrol {Tonemap mode} property is not available in Qt 5.
\section1 Applying Antialiasing
Antialiasing is used to make curved lines smoother on the screen. In the
\uicontrol Antialiasing section of the \uicontrol Properties view, you can
specify the mode and quality of antialiasing and also enable temporal
antialiasing and define its strength.
\image studio-3d-scene-environment-antialiasing.png "The Antialiasing properties"
The \uicontrol {Antialiasing mode} property specifies the mode of
antialiasing applied when the scene is rendered. Select one of the following
modes using the dropdown menu:
\table
\header
\li Mode of Antialiasing
\li Description
\row
\li MSAA
\li Applies multisample antialiasing. The scene is rendered in a
higher resolution and then scaled down to actual resolution.
\row
\li NoAA
\li No antialiasing is applied.
\row
\li SSAA
\li Supersample antialiasing is applied. The edges of geometry
are supersampled, resulting in smoother silhouettes. This
technique has no effect on the materials inside geometry.
\row
\li ProgressiveAA
\li Progressive antialiasing is applied. When the content of the
scene has stopped moving, the camera is jiggled very slightly
between frames, and the result of each new frame is blended
with the previous frames. The more frames you accumulate,
the better looking the result.
\endtable
The \uicontrol {Antialiasing quality} property sets the level of antialiasing
applied to the scene. Define the quality of antialiasing as \uicontrol Medium,
\uicontrol High, or \uicontrol {Very High}. The effect of the selected
\uicontrol {Antialiasing quality} depends on the selected
\uicontrol {Antialiasing mode}, as you can see from the table below.
In the \uicontrol SSAA mode the selected quality affects the supersampling
resolution, in \uicontrol MSAA it determines the number or samples per
pixel, and in \uicontrol ProgressiveAA it defines the number of frames for
final image.
\table
\header
\li Level of Antialiasing
\li Supersampling Resolution used in SSAA
\li Number of samples per pixel in MSAA
\li Number of frames for final image in ProgressiveAA
\row
\li Medium
\li 1.2x
\li 2
\li 2
\row
\li High
\li 1.5x
\li 4
\li 4
\row
\li Very High
\li 2.0x
\li 8
\li 8
\endtable
\note With \uicontrol {Antialiasing mode} set to \uicontrol NoAA,
\uicontrol {Antialiasing quality} does not affect antialiasing.
The \uicontrol {Temporal AA} property enables temporal antialiasing.
This means that the camera is jiggled very slightly between frames, and the
result of each new frame is blended with the previous frame.
\note Temporal antialiasing does not have an effect when the \uicontrol MSAA
mode is used.
\note When combined with \uicontrol ProgressiveAA mode, temporal antialising
is used for animations, and \uicontrol ProgressiveAA is used once
animations stop.
The \uicontrol {Temporal AA strength} property modifies the amount of
temporal movement in antialiasing. This property only has an effect when
the \uicontrol {Temporal AA} property is set to true.
\note In Qt 5, the antialiasing properties are located in
\uicontrol Properties > \uicontrol {Scene Environment}.
\section1 Applying Ambient Occlusion
Ambient occlusion is a form of approximated global illumination that causes
non-directional self-shadowing where objects are close together. You can
define the \uicontrol Strength, \uicontrol Distance, \uicontrol Softness,
\uicontrol {Sample rate}, and \uicontrol Bias properties in the
\uicontrol {Ambient Occlusion} section of the \uicontrol Properties view.
\image studio-3d-scene-environment-ambient-occlusion.png "The Ambient Occlusion properties"
You can set the strength of the shadows using the \uicontrol Strength
property, which defines the amount of ambient occlusion applied. A value of
100 causes full darkness shadows, while lower values cause the shadowing to
appear lighter. A value of 0 disables ambient occlusion entirely, thus
improving performance at a cost to the visual realism of 3D objects rendered
in the scene. All values other than 0 have the same impact on performance.
The \uicontrol Distance property defines roughly how far the ambient occlusion
shadows spread away from objects. Greater distances cause increasing impact
to performance.
The \uicontrol Softness property specifies how smooth the edges of the
ambient occlusion shading are. The value set for the property must be
between 0.0 and 50.0. To improve smoothness at the risk of sometimes
producing obvious patterned artifacts, you can scatter the edges of the
ambient occlusion shadow bands by selecting the \uicontrol {Dither} check
box.
\note Large distances between the clipping planes of your camera may cause
problems with ambient occlusion. If you are seeing odd banding in ambient
occlusion, try adjusting the value in the \uicontrol {Clip far} field in
the \l{Cameras}{scene camera} properties.
The \uicontrol {Sample rate} property specifies the number of shades of gray,
thus defining the quality of ambient occlusion at the expense of performance.
The \uicontrol Bias property defines a cutoff distance preventing objects
from exhibiting ambient occlusion at close distances. The higher the
value, the greater the distance required between objects before ambient
occlusion occurs.
\note If you see ambient occlusion shadowing on objects where there should
be no shadowing, increase the value slightly to clip away close results.
\note In Qt 5, some the ambient occlusion properties are named slightly
differently: \uicontrol {AO strength}, \uicontrol {AO distance},
\uicontrol {AO softness}, \uicontrol {AO dither}, and \uicontrol {AO bias}.
\section1 Setting the Light Probe
In the \uicontrol {Light Probe} section of the \uicontrol Properties view,
you can set the \uicontrol Image, \uicontrol Exposure, \uicontrol Horizon,
and \uicontrol Orientation properties for image-based lighting.
\image studio-3d-scene-environment-light-probe.png "The Light Probe properties"
The \uicontrol Image property defines an image used to light the scene
instead of or in addition to standard lights. The image is preferably a
high-dynamic range image or a pre-generated cubemap. Pre-baking provides
significant performance improvements at run time because no time is spent on
filtering and mipmap generation. If the source is a .hdr or other image,
the GPU-based pre-processing happens at run time after loading the image
file, which can be potentially time consuming, in particular on embedded and
mobile hardware. Therefore, it is strongly recommended that applications
pre-process .hdr images at latest at build time, as described here.
\note In Qt 6, using a \uicontrol Texture component with \uicontrol Image >
\uicontrol Source is not supported in combination with this property.
Pre-filtering of all mip levels for dynamic Qt Quick content is typically not
reasonable in practice due to performance implications. In Qt 5, the
\uicontrol Image property is referred to as \uicontrol {Light probe}, which
defines a texture for overriding or setting an image based lighting texture
for use with the skybox of the scene.
The \uicontrol Exposure property modifies the amount of light emitted by the
light probe.
When defined with increasing values, the \uicontrol Horizon property adds
darkness (black) to the bottom half of the environment, thus forcing the
lighting to come predominantly from the top of the image (and removing
specific reflections from the lower half). This property is useful for
accounting for a ground plane that would have the effect of obscuring the
reflection of the light probe from the ground. This is necessary because
light probe contributions come directily from the image without consideration
for the content of the scene. You can set the value of the
\uicontrol Horizon property between 0.0 and 1.0. Using the default value of
the property applies the entire light probe without adjustment.
\note The \uicontrol Horizon property only affects materials lighting and
has no effect on the rendering of the sky box.
\note In Qt 5, the \uicontrol Horizon property is referred to as
\uicontrol {Probe horizon}.
The \uicontrol Orientation property defines the orientation of the light
probe. Orientation is defined in terms of euler angles in degrees over the
x, y, and z axes.
\section2 Additional Light Probe Properties in Qt 5
The \uicontrol {Probe Brightness} property modifies the amount of light
emitted by the light probe.
When the \uicontrol {Fast IBL} (Fast image-based lighting) property is
enabled, more shortcuts are taken to approximate the light contribution of
the light probe at the expense of quality.
The value of the \uicontrol {Probe FOV} property sets the angle of the
image source field of view when using a camera source as the IBL probe.
*/
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