qt-everywhere-src-5.14.1/qtdeclarative/src/quick/scenegraph/util/qsgsimplematerial.cpp - orbit - Git at Google

 /****************************************************************************
 **
 ** Copyright (C) 2016 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.
 **
 ** $QT_END_LICENSE$
 **
 ****************************************************************************/

 /*!
     \class QSGSimpleMaterialShader

     \brief The QSGSimpleMaterialShader class provides a convenient way of
     building custom OpenGL-based materials for the scene graph.

     \inmodule QtQuick
     \ingroup qtquick-scenegraph-materials

     \warning This utility class is only functional when running with the legacy
     OpenGL renderer of the Qt Quick scenegraph. Its usage is not recommended in
     new application code.

     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 template <typename State> char const *const *QSGSimpleMaterialShader<State>::attributeNames() const
     \internal
  */

 /*!
     \fn template <typename State> void QSGSimpleMaterialShader<State>::initialize()
     \internal
  */

 /*!
     \fn template <typename State> void QSGSimpleMaterialShader<State>::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 template <typename State> const char *QSGSimpleMaterialShader<State>::uniformMatrixName() const

     Returns the name for the transform matrix uniform of this item.
     The default value is \c qt_Matrix.
  */

 /*!
     \fn template <typename State> const char *QSGSimpleMaterialShader<State>::uniformOpacityName() const

     Returns the name for the opacity uniform of this item.
     The default value is \c qt_Opacity.
  */

 /*!
     \fn template <typename State> void QSGSimpleMaterialShader<State>::updateState(const RenderState &state, QSGMaterial *newMaterial, QSGMaterial *oldMaterial)
     \internal
  */


 /*!
     \fn template <typename State> QList<QByteArray> QSGSimpleMaterialShader<State>::attributes() const

     Returns a list of names, declaring the vertex attributes in the
     vertex shader.
 */

 /*!
     \fn template <typename State> void QSGSimpleMaterialShader<State>::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
 */
	/****************************************************************************
	**
	** Copyright (C) 2016 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.
	**
	** $QT_END_LICENSE$
	**
	****************************************************************************/

	/*!
	\class QSGSimpleMaterialShader

	\brief The QSGSimpleMaterialShader class provides a convenient way of
	building custom OpenGL-based materials for the scene graph.

	\inmodule QtQuick
	\ingroup qtquick-scenegraph-materials

	\warning This utility class is only functional when running with the legacy
	OpenGL renderer of the Qt Quick scenegraph. Its usage is not recommended in
	new application code.

	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 template <typename State> char const const QSGSimpleMaterialShader<State>::attributeNames() const
	\internal
	*/

	/*!
	\fn template <typename State> void QSGSimpleMaterialShader<State>::initialize()
	\internal
	*/

	/*!
	\fn template <typename State> void QSGSimpleMaterialShader<State>::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 template <typename State> const char *QSGSimpleMaterialShader<State>::uniformMatrixName() const

	Returns the name for the transform matrix uniform of this item.
	The default value is \c qt_Matrix.
	*/

	/*!
	\fn template <typename State> const char *QSGSimpleMaterialShader<State>::uniformOpacityName() const

	Returns the name for the opacity uniform of this item.
	The default value is \c qt_Opacity.
	*/

	/*!
	\fn template <typename State> void QSGSimpleMaterialShader<State>::updateState(const RenderState &state, QSGMaterial newMaterial, QSGMaterial oldMaterial)
	\internal
	*/


	/*!
	\fn template <typename State> QList<QByteArray> QSGSimpleMaterialShader<State>::attributes() const

	Returns a list of names, declaring the vertex attributes in the
	vertex shader.
	*/

	/*!
	\fn template <typename State> void QSGSimpleMaterialShader<State>::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
	*/