Add the graphics api independent scenegraph port

Opt in via environment variables:
QSG_RHI=1 -> enable using QRhi instead of GL
QSG_RHI_BACKEND -> set to vulkan, metal, d3d11, gl to override the default
(the default is d3d11 on Windows, metal on Mac, gl elsewhere)

Or force a given rhi backend via the existing
QQuickWindow::setSceneGraphBackend().

Otherwise the default behavior is the same as before, the rhi code path
is never active by default.

-no-opengl builds are supported in the sense that they work and default
to the software backend. However, the rhi code path cannot currently be
used in such builds, even though QRhi from qtbase is fully functional
with Vulkan, D3D, or Metal even when qtbase was configured with
-no-opengl. This cannot be utilized by Quick atm due to OpenGL usage
being all over the place in the sources corresponding to the default
backend, and those host the rhi code path as well. This will be cleaned up
hopefully in Qt 6, with the removal all direct OpenGL usage.

Other env.vars.:
QSG_RHI_DEBUG_LAYER=1 -> enable D3D debug or Vulkan validation layer
(assuming the system is set up for this)
QSG_RHI_SHADEREFFECT_DEBUG=1 -> print stuff from ShaderEffect
QSG_SAMPLES=1,2,4,... -> MSAA sample count (but QSurfaceFormat works too)
QT_D3D_ADAPTER_INDEX=0,1,... -> D3D adapter index
QT_VK_PHYSICAL_DEVICE_INDEX=0,1,... -> Vulkan physical device index
QSG_RHI_UINT32_INDEX=1 -> always use uint index data (both
merged/unmerged, convert when needed - with some rhi backends this is
implicit)
QSG_RENDER_LOOP -> to override the render loop as usual. The default
with RHI is threaded for Metal, threaded for Vulkan on Windows, basic
for Vulkan on Linux and Android (to be checked later), while the existing
rules apply for OpenGL.

Not supported when running with QRhi:
  - particles
  - compressed atlases (though this is transparent to the apps)
  - QSGRenderNode
  - QQuickRenderControl
  - QQuickFramebufferObject
  - certain QQuickWindow functionality that depends directly on OpenGL
  - anisotropic filtering for textures
  - native text may lack some gamma correction
  - QSGEngine applicability unclear
  - some QML profiler logs may be incorrect or irrelevant

Change-Id: I7822e99ad79e342e4166275da6e9e66498d76521
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 556 insertions, 0 deletions

diff --git a/src/quick/scenegraph/coreapi/qsgmaterialshader.cpp b/src/quick/scenegraph/coreapi/qsgmaterialshader.cpp
new file mode 100644
index 0000000000..d614f9be4c
--- /dev/null
+++ b/src/quick/scenegraph/coreapi/qsgmaterialshader.cpp
@@ -0,0 +1,556 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qsgmaterial.h"
+#include "qsgrenderer_p.h"
+#include "qsgmaterialshader_p.h"
+#if QT_CONFIG(opengl)
+# include <private/qsgshadersourcebuilder_p.h>
+# include <private/qsgdefaultcontext_p.h>
+# include <private/qsgdefaultrendercontext_p.h>
+# include <QtGui/QOpenGLFunctions>
+# include <QtGui/QOpenGLContext>
+#endif
+
+QT_BEGIN_NAMESPACE
+
+#if QT_CONFIG(opengl)
+const char *QSGMaterialShaderPrivate::loadShaderSource(QOpenGLShader::ShaderType type) const
+{
+    const QStringList files = m_sourceFiles[type];
+    QSGShaderSourceBuilder builder;
+    for (const QString &file : files)
+        builder.appendSourceFile(file);
+    m_sources[type] = builder.source();
+    return m_sources[type].constData();
+}
+#endif
+
+/*!
+    \class QSGMaterialShader
+    \brief The QSGMaterialShader class represents an OpenGL shader program
+    in the renderer.
+    \inmodule QtQuick
+    \ingroup qtquick-scenegraph-materials
+
+    The QSGMaterialShader API is relatively low-level. A more convenient API,
+    which provides almost all the same features, is available through
+    QSGSimpleMaterialShader.
+
+    \warning This class is only functional when running with the legacy OpenGL
+    renderer of the Qt Quick scenegraph.
+
+    The QSGMaterial and QSGMaterialShader form a tight relationship. For one
+    scene graph (including nested graphs), there is one unique QSGMaterialShader
+    instance which encapsulates the QOpenGLShaderProgram the scene graph uses
+    to render that material, such as a shader to flat coloring of geometry.
+    Each QSGGeometryNode can have a unique QSGMaterial containing the
+    how the shader should be configured when drawing that node, such as
+    the actual color used to render the geometry.
+
+    An instance of QSGMaterialShader is never created explicitly by the user,
+    it will be created on demand by the scene graph through
+    QSGMaterial::createShader(). The scene graph will make sure that there
+    is only one instance of each shader implementation through a scene graph.
+
+    The source code returned from vertexShader() is used to control what the
+    material does with the vertiex data that comes in from the geometry.
+    The source code returned from the fragmentShader() is used to control
+    what how the material should fill each individual pixel in the geometry.
+    The vertex and fragment source code is queried once during initialization,
+    changing what is returned from these functions later will not have
+    any effect.
+
+    The activate() function is called by the scene graph when a shader is
+    is starting to be used. The deactivate function is called by the scene
+    graph when the shader is no longer going to be used. While active,
+    the scene graph may make one or more calls to updateState() which
+    will update the state of the shader for each individual geometry to
+    render.
+
+    The attributeNames() returns the name of the attributes used in the
+    vertexShader(). These are used in the default implementation of
+    activate() and deactivate() to decide whice vertex registers are enabled.
+
+    The initialize() function is called during program creation to allow
+    subclasses to prepare for use, such as resolve uniform names in the
+    vertexShader() and fragmentShader().
+
+    A minimal example:
+    \code
+        class Shader : public QSGMaterialShader
+        {
+        public:
+            const char *vertexShader() const {
+                return
+                "attribute highp vec4 vertex;          \n"
+                "uniform highp mat4 matrix;            \n"
+                "void main() {                         \n"
+                "    gl_Position = matrix * vertex;    \n"
+                "}";
+            }
+
+            const char *fragmentShader() const {
+                return
+                "uniform lowp float opacity;                            \n"
+                "void main() {                                          \n"
+                        "    gl_FragColor = vec4(1, 0, 0, 1) * opacity; \n"
+                "}";
+            }
+
+            char const *const *attributeNames() const
+            {
+                static char const *const names[] = { "vertex", 0 };
+                return names;
+            }
+
+            void initialize()
+            {
+                QSGMaterialShader::initialize();
+                m_id_matrix = program()->uniformLocation("matrix");
+                m_id_opacity = program()->uniformLocation("opacity");
+            }
+
+            void updateState(const RenderState &state, QSGMaterial *newMaterial, QSGMaterial *oldMaterial)
+            {
+                Q_ASSERT(program()->isLinked());
+                if (state.isMatrixDirty())
+                    program()->setUniformValue(m_id_matrix, state.combinedMatrix());
+                if (state.isOpacityDirty())
+                    program()->setUniformValue(m_id_opacity, state.opacity());
+            }
+
+        private:
+            int m_id_matrix;
+            int m_id_opacity;
+        };
+    \endcode
+
+    \note All classes with QSG prefix should be used solely on the scene graph's
+    rendering thread. See \l {Scene Graph and Rendering} for more information.
+
+ */
+
+
+
+/*!
+    Creates a new QSGMaterialShader.
+ */
+QSGMaterialShader::QSGMaterialShader()
+    : d_ptr(new QSGMaterialShaderPrivate)
+{
+}
+
+/*!
+    \internal
+ */
+QSGMaterialShader::QSGMaterialShader(QSGMaterialShaderPrivate &dd)
+    : d_ptr(&dd)
+{
+}
+
+/*!
+    \internal
+ */
+QSGMaterialShader::~QSGMaterialShader()
+{
+}
+
+/*!
+    \fn char const *const *QSGMaterialShader::attributeNames() const
+
+    Returns a zero-terminated array describing the names of the
+    attributes used in the vertex shader.
+
+    This function is called when the shader is compiled to specify
+    which attributes exist. The order of the attribute names
+    defines the attribute register position in the vertex shader.
+ */
+
+#if QT_CONFIG(opengl)
+/*!
+    \fn const char *QSGMaterialShader::vertexShader() const
+
+    Called when the shader is being initialized to get the vertex
+    shader source code.
+
+    The contents returned from this function should never change.
+*/
+const char *QSGMaterialShader::vertexShader() const
+{
+    Q_D(const QSGMaterialShader);
+    return d->loadShaderSource(QOpenGLShader::Vertex);
+}
+
+
+/*!
+   \fn const char *QSGMaterialShader::fragmentShader() const
+
+    Called when the shader is being initialized to get the fragment
+    shader source code.
+
+    The contents returned from this function should never change.
+*/
+const char *QSGMaterialShader::fragmentShader() const
+{
+    Q_D(const QSGMaterialShader);
+    return d->loadShaderSource(QOpenGLShader::Fragment);
+}
+
+
+/*!
+    \fn QOpenGLShaderProgram *QSGMaterialShader::program()
+
+    Returns the shader program used by this QSGMaterialShader.
+ */
+#endif
+
+/*!
+    \fn void QSGMaterialShader::initialize()
+
+    Reimplement this function to do one-time initialization when the
+    shader program is compiled. The OpenGL shader program is compiled
+    and linked, but not bound, when this function is called.
+ */
+
+
+/*!
+    This function is called by the scene graph to indicate that geometry is
+    about to be rendered using this shader.
+
+    State that is global for all uses of the shader, independent of the geometry
+    that is being drawn, can be setup in this function.
+ */
+
+void QSGMaterialShader::activate()
+{
+}
+
+
+
+/*!
+    This function is called by the scene graph to indicate that geometry will
+    no longer to be rendered using this shader.
+ */
+
+void QSGMaterialShader::deactivate()
+{
+}
+
+
+
+/*!
+    This function is called by the scene graph before geometry is rendered
+    to make sure the shader is in the right state.
+
+    The current rendering \a state is passed from the scene graph. If the state
+    indicates that any state is dirty, the updateState implementation must
+    update accordingly for the geometry to render correctly.
+
+    The subclass specific state, such as the color of a flat color material, should
+    be extracted from \a newMaterial to update the color uniforms accordingly.
+
+    The \a oldMaterial can be used to minimze state changes when updating
+    material states. The \a oldMaterial is 0 if this shader was just activated.
+
+    \sa activate(), deactivate()
+ */
+
+void QSGMaterialShader::updateState(const RenderState & /* state */, QSGMaterial * /* newMaterial */, QSGMaterial * /* oldMaterial */)
+{
+}
+
+#if QT_CONFIG(opengl)
+/*!
+    Sets the GLSL source file for the shader stage \a type to \a sourceFile. The
+    default implementation of the vertexShader() and fragmentShader() functions
+    will load the source files set by this function.
+
+    This function is useful when you have a single source file for a given shader
+    stage. If your shader consists of multiple source files then use
+    setShaderSourceFiles()
+
+    \sa setShaderSourceFiles(), vertexShader(), fragmentShader()
+ */
+void QSGMaterialShader::setShaderSourceFile(QOpenGLShader::ShaderType type, const QString &sourceFile)
+{
+    Q_D(QSGMaterialShader);
+    d->m_sourceFiles[type] = (QStringList() << sourceFile);
+}
+
+/*!
+    Sets the GLSL source files for the shader stage \a type to \a sourceFiles. The
+    default implementation of the vertexShader() and fragmentShader() functions
+    will load the source files set by this function in the order given.
+
+    \sa setShaderSourceFile(), vertexShader(), fragmentShader()
+ */
+void QSGMaterialShader::setShaderSourceFiles(QOpenGLShader::ShaderType type, const QStringList &sourceFiles)
+{
+    Q_D(QSGMaterialShader);
+    d->m_sourceFiles[type] = sourceFiles;
+}
+
+/*!
+    This function is called when the shader is initialized to compile the
+    actual QOpenGLShaderProgram. Do not call it explicitly.
+
+    The default implementation will extract the vertexShader() and
+    fragmentShader() and bind the names returned from attributeNames()
+    to consecutive vertex attribute registers starting at 0.
+ */
+
+void QSGMaterialShader::compile()
+{
+    Q_ASSERT_X(!m_program.isLinked(), "QSGSMaterialShader::compile()", "Compile called multiple times!");
+
+    program()->addCacheableShaderFromSourceCode(QOpenGLShader::Vertex, vertexShader());
+    program()->addCacheableShaderFromSourceCode(QOpenGLShader::Fragment, fragmentShader());
+
+    char const *const *attr = attributeNames();
+#ifndef QT_NO_DEBUG
+    int maxVertexAttribs = 0;
+    QOpenGLFunctions *funcs = QOpenGLContext::currentContext()->functions();
+    funcs->glGetIntegerv(GL_MAX_VERTEX_ATTRIBS, &maxVertexAttribs);
+    for (int i = 0; attr[i]; ++i) {
+        if (i >= maxVertexAttribs) {
+            qFatal("List of attribute names is either too long or not null-terminated.\n"
+                   "Maximum number of attributes on this hardware is %i.\n"
+                   "Vertex shader:\n%s\n"
+                   "Fragment shader:\n%s\n",
+                   maxVertexAttribs, vertexShader(), fragmentShader());
+        }
+        if (*attr[i])
+            program()->bindAttributeLocation(attr[i], i);
+    }
+#else
+    for (int i = 0; attr[i]; ++i) {
+        if (*attr[i])
+            program()->bindAttributeLocation(attr[i], i);
+    }
+#endif
+
+    if (!program()->link()) {
+        qWarning("QSGMaterialShader: Shader compilation failed:");
+        qWarning() << program()->log();
+    }
+}
+
+#endif
+
+/*!
+    \class QSGMaterialShader::RenderState
+    \brief The QSGMaterialShader::RenderState encapsulates the current rendering state
+    during a call to QSGMaterialShader::updateState().
+    \inmodule QtQuick
+
+    The render state contains a number of accessors that the shader needs to respect
+    in order to conform to the current state of the scene graph.
+
+    The instance is only valid inside a call to QSGMaterialShader::updateState() and
+    should not be used outisde this function.
+ */
+
+
+
+/*!
+    \enum QSGMaterialShader::RenderState::DirtyState
+
+    \value DirtyMatrix Used to indicate that the matrix has changed and must be updated.
+
+    \value DirtyOpacity Used to indicate that the opacity has changed and must be updated.
+
+    \value DirtyCachedMaterialData Used to indicate that the cached material data have changed and must be updated.
+
+    \value DirtyAll Used to indicate that everything needs to be updated.
+ */
+
+
+
+/*!
+    \fn bool QSGMaterialShader::RenderState::isMatrixDirty() const
+
+    Returns \c true if the dirtyStates() contain the dirty matrix state,
+    otherwise returns \c false.
+ */
+
+
+
+/*!
+    \fn bool QSGMaterialShader::RenderState::isOpacityDirty() const
+
+    Returns \c true if the dirtyStates() contains the dirty opacity state,
+    otherwise returns \c false.
+ */
+
+/*!
+  \fn bool QSGMaterialShader::RenderState::isCachedMaterialDataDirty() const
+
+  Returns \c true if the dirtyStates() contains the dirty cached material state,
+  otherwise returns \c false.
+ */
+
+/*!
+    \fn QSGMaterialShader::RenderState::DirtyStates QSGMaterialShader::RenderState::dirtyStates() const
+
+    Returns which rendering states that have changed and needs to be updated
+    for geometry rendered with this material to conform to the current
+    rendering state.
+ */
+
+
+
+/*!
+    Returns the accumulated opacity to be used for rendering.
+ */
+
+float QSGMaterialShader::RenderState::opacity() const
+{
+    Q_ASSERT(m_data);
+    return static_cast<const QSGRenderer *>(m_data)->currentOpacity();
+}
+
+/*!
+    Returns the modelview determinant to be used for rendering.
+ */
+
+float QSGMaterialShader::RenderState::determinant() const
+{
+    Q_ASSERT(m_data);
+    return static_cast<const QSGRenderer *>(m_data)->determinant();
+}
+
+/*!
+    Returns the matrix combined of modelview matrix and project matrix.
+ */
+
+QMatrix4x4 QSGMaterialShader::RenderState::combinedMatrix() const
+{
+    Q_ASSERT(m_data);
+    return static_cast<const QSGRenderer *>(m_data)->currentCombinedMatrix();
+}
+/*!
+   Returns the ratio between physical pixels and device-independent pixels
+   to be used for rendering.
+*/
+float QSGMaterialShader::RenderState::devicePixelRatio() const
+{
+    Q_ASSERT(m_data);
+    return static_cast<const QSGRenderer *>(m_data)->devicePixelRatio();
+}
+
+
+
+/*!
+    Returns the model view matrix.
+
+    If the material has the RequiresFullMatrix flag
+    set, this is guaranteed to be the complete transform
+    matrix calculated from the scenegraph.
+
+    However, if this flag is not set, the renderer may
+    choose to alter this matrix. For example, it may
+    pre-transform vertices on the CPU and set this matrix
+    to identity.
+
+    In a situation such as the above, it is still possible
+    to retrieve the actual matrix determinant by setting
+    the RequiresDeterminant flag in the material and
+    calling the determinant() accessor.
+ */
+
+QMatrix4x4 QSGMaterialShader::RenderState::modelViewMatrix() const
+{
+    Q_ASSERT(m_data);
+    return static_cast<const QSGRenderer *>(m_data)->currentModelViewMatrix();
+}
+
+/*!
+    Returns the projection matrix.
+ */
+
+QMatrix4x4 QSGMaterialShader::RenderState::projectionMatrix() const
+{
+    Q_ASSERT(m_data);
+    return static_cast<const QSGRenderer *>(m_data)->currentProjectionMatrix();
+}
+
+
+
+/*!
+    Returns the viewport rect of the surface being rendered to.
+ */
+
+QRect QSGMaterialShader::RenderState::viewportRect() const
+{
+    Q_ASSERT(m_data);
+    return static_cast<const QSGRenderer *>(m_data)->viewportRect();
+}
+
+
+
+/*!
+    Returns the device rect of the surface being rendered to
+ */
+
+QRect QSGMaterialShader::RenderState::deviceRect() const
+{
+    Q_ASSERT(m_data);
+    return static_cast<const QSGRenderer *>(m_data)->deviceRect();
+}
+
+#if QT_CONFIG(opengl)
+
+/*!
+    Returns the QOpenGLContext that is being used for rendering
+ */
+
+QOpenGLContext *QSGMaterialShader::RenderState::context() const
+{
+    // Only the QSGDefaultRenderContext will have an OpenGL Context to query
+    auto openGLRenderContext = static_cast<const QSGDefaultRenderContext *>(static_cast<const QSGRenderer *>(m_data)->context());
+    if (openGLRenderContext != nullptr)
+        return openGLRenderContext->openglContext();
+    else
+        return nullptr;
+}
+
+#endif
+
+QT_END_NAMESPACE