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/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtQuick3D module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** GNU Lesser General Public License Usage
** This file may be used under the terms of the GNU Lesser General Public
** License version 2.1 as published by the Free Software Foundation and
** appearing in the file LICENSE.LGPL included in the packaging of this
** file. Please review the following information to ensure the GNU Lesser
** General Public License version 2.1 requirements will be met:
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU General
** Public License version 3.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of this
** file. Please review the following information to ensure the GNU General
** Public License version 3.0 requirements will be met:
** http://www.gnu.org/copyleft/gpl.html.
**
** Other Usage
** Alternatively, this file may be used in accordance with the terms and
** conditions contained in a signed written agreement between you and Nokia.
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "qglabstractmaterial.h"
QT_BEGIN_NAMESPACE
/*!
\class QGLAbstractMaterial
\since 4.8
\brief The QGLAbstractMaterial class provides a standard interface for rendering surface materials with GL.
\ingroup qt3d
\ingroup qt3d::materials
Materials are the primary method to specify the surface appearance of an
object, as distinct from the geometry for the object. Materials have an
almost endless variety of parameters:
\list
\o Properties of the material under various lighting conditions;
i.e., the traditional parameters for ambient, diffuse, specular, etc.
\o Textures in multiple layers, with different combination modes;
decal, modulate, replace, etc.
\o Environmental conditions such as fogging.
\o Alpha values for opacity and blending.
\o Interpolation factors for animated surface effects.
\o etc
\endlist
QGLAbstractMaterial is the base class for all such materials.
It provides a very simple API to bind() a material to a QGLPainter
when the material needs to be rendered, to release() a material
from a QGLPainter when the material is no longer needed, and to
prepareToDraw().
Subclasses of QGLAbstractMaterial implement specific materials.
QGLMaterial provides the traditional ambient, diffuse, specular, etc
parameters for lighting properties.
Materials are distinct from \i effects, which have the base class
QGLAbstractEffect. Effects are typically shader programs that are
used to render a specific type of material. The material's bind()
function will use QGLPainter::setStandardEffect() or
QGLPainter::setUserEffect() to select the exact effect that is
needed to render the material.
It is possible that the same material may be rendered with different
effects depending upon the material parameters. For example, a lit
material may select a simpler and more efficient shader program effect
if the material has the default spotlight properties, or if the
QGLPainter only has a single light source specified.
\sa QGLMaterial, QGLAbstractEffect
*/
/*!
Constructs a new material and attaches it to \a parent.
*/
QGLAbstractMaterial::QGLAbstractMaterial(QObject *parent)
: QObject(parent)
{
}
/*!
Destroys this material.
*/
QGLAbstractMaterial::~QGLAbstractMaterial()
{
}
/*!
Returns the material lighting parameters for rendering the front
faces of fragments with this abstract material. The default
implementation returns null.
This function is provided as a convenience for applications that
wish to alter the lighting parameters or textures of a material,
without regard to any wrapping that has been performed to add
blending or other options.
\sa back(), QGLMaterial
*/
QGLMaterial *QGLAbstractMaterial::front() const
{
return 0;
}
/*!
Returns the material lighting parameters for rendering the back
faces of fragments with this abstract material. The default
implementation returns null, which indicates that front()
is also used to render back faces.
\sa front(), QGLMaterial
*/
QGLMaterial *QGLAbstractMaterial::back() const
{
return 0;
}
/*!
\fn bool QGLAbstractMaterial::isTransparent() const
Returns true if this material is transparent and will therefore
require the \c{GL_BLEND} mode to be enabled to render the material.
Returns false if the material is fully opaque.
*/
/*!
\fn void QGLAbstractMaterial::bind(QGLPainter *painter)
Binds resources to \a painter that are needed to render this
material; textures, shader programs, blending modes, etc.
In the following example, lit material parameters and a texture
are bound to the \a painter, for rendering with the standard
QGL::LitModulateTexture2D effect:
\code
void TexturedLitMaterial::bind(QGLPainter *painter)
{
painter->setStandardEffect(QGL::LitModulateTexture2D);
painter->setFaceMaterial(QGL::AllFaces, material);
painter->glActiveTexture(GL_TEXTURE0);
texture->bind();
}
\endcode
Normally the effect is bound to \a painter during the bind()
function. However, some materials may need to use different
effects depending upon which attributes are present in the
geometry. For example, a per-vertex color effect instead of a
uniform color effect if the geometry has the QGL::Color attribute.
The prepareToDraw() function can be overridden to alter the
effect once the specific set of geometry attributes are known.
\sa release(), prepareToDraw()
*/
/*!
\fn void QGLAbstractMaterial::release(QGLPainter *painter, QGLAbstractMaterial *next)
Releases resources from \a painter that were used to render this
material. The QGLPainter::effect() can be left bound to \a painter,
but other resources such as textures and blending modes
should be disabled.
If \a next is not null, then it indicates the next material that
will be bound to \a painter. If \a next is the same type of
material as this material, then this function can choose not to
release resources that would be immediately re-bound to
\a painter in the next call to bind().
In the following example, texture unit 0 is unbound if \a painter
is about to switch to another effect that is not an instance
of \c{TexturedLitMaterial}:
\code
void TexturedLitMaterial::release(QGLPainter *painter, QGLAbstractMaterial *next)
{
if (!qobject_cast<TexturedLitMaterial *>(next)) {
painter->glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, 0);
}
}
\endcode
\sa bind(), prepareToDraw()
*/
/*!
Prepares to draw geometry to \a painter that has the specified
set of vertex \a attributes. The default implementation
does nothing.
Multiple effects may be used to render some materials depending upon
the available vertex attributes. For example, if QGL::Color is
present in \a attributes, then a per-vertex color should be used
instead of a single uniform color.
This function is provided for such materials to have one last
chance during QGLPainter::draw() to alter the QGLPainter::effect()
to something that is tuned for the specific geometry. It can
be assumed that bind() has already been called on this material.
\sa bind(), release()
*/
void QGLAbstractMaterial::prepareToDraw(QGLPainter *painter, const QGLAttributeSet &attributes)
{
Q_UNUSED(painter);
Q_UNUSED(attributes);
}
/*!
\fn void QGLAbstractMaterial::materialChanged()
Signal that is emitted when an object that is using this material
should be redrawn because some property on the material has changed.
*/
QT_END_NAMESPACE
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