Use cubeMaps for IBL texture sources

This changes how IBL sources are pre-processed and used at runtime.
Previously we would directly use the equirectangular texture data. This
led to several issues:
- A Compute shader was required at runtime to pre-filter each mip level
(which depended on the previous level).  Compute shaders are not
available everywhere, and doing the software version at runtime was very
expensive.
- Even when we had support for compute shaders the minimium number of
compute units available was not enough for decent processing.
- The method we were using for pre-filtering was not what we needed for
doing proper BRDF.
- Using equirectangular textures at runtime is expensive because each
time we want to sample the texture we have to convert the coordinate
space.
- Using equirectangular projections leads to artifacts at the poles
which lead to obvious artifacts in the skybox, as well as specular
reflections which depend on values samples against those poles.
- The lack of irradiance data let to very dark diffuse contributions.

So instead of using a prefiltered equirectangular texture directly, now
we create a cubeMap from the provided texture using a series of standard
shading passes which contains pre-filtered environment mip levels for
BRDF as well as a pre-convolved irradiance map. This eliminates all of
the above issues.

Fixes: QTBUG-78849
Fixes: QTBUG-86682
Fixes: QTBUG-86684
Fixes: QTBUG-86685
Fixes: QTBUG-86795
Change-Id: I7dcd059c8b669142fc5c368f4dbfeed199a57f16
Reviewed-by: Laszlo Agocs <[email protected]>

1 files changed, 0 insertions, 5 deletions

diff --git a/src/quick3d/qquick3dsceneenvironment_p.h b/src/quick3d/qquick3dsceneenvironment_p.h
index d2689b4e..01d2c007 100644
--- a/src/quick3d/qquick3dsceneenvironment_p.h
+++ b/src/quick3d/qquick3dsceneenvironment_p.h
@@ -78,7 +78,6 @@ class Q_QUICK3D_EXPORT QQuick3DSceneEnvironment : public QQuick3DObject
     Q_PROPERTY(QQuick3DTexture *lightProbe READ lightProbe WRITE setLightProbe NOTIFY lightProbeChanged)
     Q_PROPERTY(float probeExposure READ probeExposure WRITE setProbeExposure NOTIFY probeExposureChanged)
     Q_PROPERTY(float probeHorizon READ probeHorizon WRITE setProbeHorizon NOTIFY probeHorizonChanged)
-    Q_PROPERTY(float probeFieldOfView READ probeFieldOfView WRITE setProbeFieldOfView NOTIFY probeFieldOfViewChanged)
     Q_PROPERTY(QVector3D probeOrientation READ probeOrientation WRITE setProbeOrientation NOTIFY probeOrientationChanged)
 
     Q_PROPERTY(QQuick3DEnvironmentTonemapModes tonemapMode READ tonemapMode WRITE setTonemapMode NOTIFY tonemapModeChanged)
@@ -143,7 +142,6 @@ public:
     QQuick3DTexture *lightProbe() const;
     float probeExposure() const;
     float probeHorizon() const;
-    float probeFieldOfView() const;
     QVector3D probeOrientation() const;
 
     bool depthTestEnabled() const;
@@ -173,7 +171,6 @@ public Q_SLOTS:
     void setLightProbe(QQuick3DTexture *lightProbe);
     void setProbeExposure(float probeExposure);
     void setProbeHorizon(float probeHorizon);
-    void setProbeFieldOfView(float probeFieldOfView);
     void setProbeOrientation(const QVector3D &orientation);
 
     void setDepthTestEnabled(bool depthTestEnabled);
@@ -200,7 +197,6 @@ Q_SIGNALS:
     void lightProbeChanged();
     void probeExposureChanged();
     void probeHorizonChanged();
-    void probeFieldOfViewChanged();
     void probeOrientationChanged();
 
     void depthTestEnabledChanged();
@@ -241,7 +237,6 @@ private:
     QQuick3DTexture *m_lightProbe = nullptr;
     float m_probeExposure = 1.0f;
     float m_probeHorizon = -1.0f;
-    float m_probeFieldOfView = 180.0f;
     QVector3D m_probeOrientation;
 
     ConnectionMap m_connections;