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/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the QtQuick module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** 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 http://www.qt.io/terms-conditions. For further
** information use the contact form at http://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 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** As a special exception, The Qt Company gives you certain additional
** rights. These rights are described in The Qt Company LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** $QT_END_LICENSE$
**
****************************************************************************/
/*!
\class QSGSimpleMaterialShader
\brief The QSGSimpleMaterialShader class provides a convenient way of
building custom materials for the scene graph.
\inmodule QtQuick
\ingroup qtquick-scenegraph-materials
Where the QSGMaterial and QSGMaterialShader API requires a bit of
boilerplate code to create a functioning material, the
QSGSimpleMaterialShader tries to hide some of this through the use
of templates.
QSGSimpleMaterialShader::vertexShader() and
QSGSimpleMaterialShader::fragmentShader() are used to specify the
actual shader source code. The names of the vertex attributes
should be listed in the QSGSimpleMaterialShader::attributes()
QSGSimpleMaterialShader::updateState() is used to push the material
state to the OpenGL shader program.
The actual OpenGL shader program is accessible through the
QSGSimpleMaterialShader::program() function.
Each QSGSimpleMaterialShader implementation operates on a unique
state struct. The state struct must be declared using the
\c {QSG_DECLARE_SIMPLE_SHADER} macro.
Here is a simple example of a custom solid-color:
\code
struct Color
{
float r, g, b, a;
};
class MinimalShader : public QSGSimpleMaterialShader<Color>
{
QSG_DECLARE_SIMPLE_SHADER(MinimalShader, Color)
public:
const char *vertexShader() const {
return
"attribute highp vec4 vertex; \n"
"uniform highp mat4 qt_Matrix; \n"
"void main() { \n"
" gl_Position = qt_Matrix * vertex; \n"
"}";
}
const char *fragmentShader() const {
return
"uniform lowp float qt_Opacity; \n"
"uniform lowp vec4 color; \n"
"void main() { \n"
" gl_FragColor = color * qt_Opacity; \n"
"}";
}
QList<QByteArray> attributes() const {
return QList<QByteArray>() << "vertex";
}
void updateState(const Color *color, const Color *) {
program()->setUniformValue("color", color->r, color->g, color->b, color->a);
}
};
\endcode
Instances of materials using this shader can be created using the
createMaterial() function which will be defined by the
QSG_DECLARE_SIMPLE_SHADER macro.
\code
QSGSimpleMaterial<Color> *material = MinimalShader::createMaterial();
material->state()->r = 1;
material->state()->g = 0;
material->state()->b = 0;
material->state()->a = 1;
node->setMaterial(material);
\endcode
The scene graph will often try to find materials that have the
same or at least similar state so that these can be batched
together inside the renderer, which gives better performance. To
specify sortable material states, use
QSG_DECLARE_SIMPLE_COMPARABLE_SHADER instead of
QSG_DECLARE_SIMPLE_SHADER. The state struct must then also define
the function:
\code
int compare(const Type *other) const;
\endcode
\warning The QSGSimpleMaterialShader relies on template
instantiation to create a QSGMaterialType which the scene graph
renderer internally uses to identify this shader. For this reason,
the unique QSGSimpleMaterialShader implementation must be
instantiated with a unique C++ type.
\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.
\sa {Scene Graph - Simple Material}
*/
/*!
\macro QSG_DECLARE_SIMPLE_SHADER(Shader, State)
\relates QSGSimpleMaterialShader
This macro is used to declare a QSGMaterialType and a \c
createMaterial() function for \a Shader with the given \a State.
*/
/*!
\macro QSG_DECLARE_SIMPLE_COMPARABLE_SHADER(Shader, State)
\relates QSGSimpleMaterialShader
This macro is used to declare a QSGMaterialType and a \c
createMaterial() function for \a Shader with the given \a State,
where the \a State class must define a compare function on the
form:
\code
int compare(const State *other) const;
\endcode
*/
/*!
\fn char const *const *QSGSimpleMaterialShader::attributeNames() const
\internal
*/
/*!
\fn void QSGSimpleMaterialShader::initialize()
\internal
*/
/*!
\fn void QSGSimpleMaterialShader::resolveUniforms()
Reimplement this function to resolve the location of named uniforms
in the shader program.
This function is called when the material shader is initialized.
*/
/*!
\fn const char *QSGSimpleMaterialShader::uniformMatrixName() const
Reimplement this function to give a different name to the uniform for
item transformation. The default value is \c qt_Matrix.
*/
/*!
\fn const char *QSGSimpleMaterialShader::uniformOpacityName() const
Reimplement this function to give a different name to the uniform for
item opacity. The default value is \c qt_Opacity.
If the shader program does not implement the item opacity, the
implemented function should return a null pointer.
*/
/*!
\fn void QSGSimpleMaterialShader::updateState(const RenderState &state, QSGMaterial *newMaterial, QSGMaterial *oldMaterial)
\internal
*/
/*!
\fn QList<QByteArray> QSGSimpleMaterialShader::attributes() const
Returns a list of names, declaring the vertex attributes in the
vertex shader.
*/
/*!
\fn void QSGSimpleMaterialShader::updateState(const State *newState, const State *oldState)
Called whenever the state of this shader should be updated from
\a oldState to \a newState, typical for each new set of
geometries being drawn.
Both the old and the new state are passed in so that the
implementation can compare and minimize the state changes when
applicable.
*/
/*!
\class QSGSimpleMaterial
\inmodule QtQuick
\ingroup qtquick-scenegraph-materials
\brief The QSGSimpleMaterial class is a template generated class
used to store the state used with a QSGSimpleMateralShader.
The state of the material is accessible through the template
generated state() function.
\inmodule QtQuick
\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.
\sa QSGSimpleMaterialShader
*/
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