aboutsummaryrefslogtreecommitdiffstats
path: root/src/quick/scenegraph/coreapi/qsgmaterial.cpp
blob: 709ab6c0394950e3085c1a7d799af92da7d813a6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
/****************************************************************************
**
** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtDeclarative 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 "qsgmaterial.h"
#include "qsgrenderer_p.h"

QT_BEGIN_NAMESPACE


/*!
    \class QSGMaterialShader
    \brief The QSGMaterialShader class implements a material renders geometry.

    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 to used to render the geometry.

    An instance of QSGMaterialShader is never created explicitely 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 deactive() 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

    \warning Instances of QSGMaterialShader belongs to the Scene Graph rendering
    thread, and cannot be used from the GUI thread.

 */



/*!
    Creates a new QSGMaterialShader.
 */
QSGMaterialShader::QSGMaterialShader()
{
}



/*!
    \fn QOpenGLShaderProgram *QSGMaterialShader::program() const

    Returns the shader program used by this QSGMaterialShader.
 */



/*!
    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.

    If reimplemented, make sure to either call the base class implementation to
    enable the vertex attribute registers.
 */

void QSGMaterialShader::activate()
{
    Q_ASSERT(program()->isLinked());

    program()->bind();
    char const *const *attr = attributeNames();
    for (int i = 0; attr[i]; ++i) {
        if (*attr[i])
            program()->enableAttributeArray(i);
    }
}



/*!
    This function is called by the scene graph to indicate that geometry will
    no longer to be rendered using this shader.

    If reimplemented, make sure to either call the base class implementation to
    disable the vertex attribute registers.
 */

void QSGMaterialShader::deactivate()
{
    char const *const *attr = attributeNames();
    for (int i = 0; attr[i]; ++i) {
        if (*attr[i])
            program()->disableAttributeArray(i);
    }
}



/*!
    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 */)
{
}



/*!
    This function is called when the shader is initialized to compile the
    actual QOpenGLShaderProgram. Do not call it explicitely.

    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()->addShaderFromSourceCode(QOpenGLShader::Vertex, vertexShader());
    program()->addShaderFromSourceCode(QOpenGLShader::Fragment, fragmentShader());

    char const *const *attr = attributeNames();
#ifndef QT_NO_DEBUG
    int maxVertexAttribs = 0;
    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();
    }
}



/*!
    \class QSGMaterialShader::RenderState
    \brief The QSGMaterialShader::RenderState encapsulates the current rendering state
    during a call to QSGMaterialShader::updateState().

    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.
 */



/*!
    \fn bool QSGMaterialShader::RenderState::isMatrixDirty() const

    Convenience function to check if the dirtyStates() indicates that the matrix
    needs to be updated.
 */



/*!
    \fn bool QSGMaterialShader::RenderState::isOpacityDirty() const

    Conveience function to check if the dirtyStates() indicates that the opacity
    needs to be updated.
 */



/*!
    \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 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 model view matrix.
 */

QMatrix4x4 QSGMaterialShader::RenderState::modelViewMatrix() const
{
    Q_ASSERT(m_data);
    return static_cast<const QSGRenderer *>(m_data)->currentModelViewMatrix();
}



/*!
    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();
}



/*!
    Returns the QOpenGLContext that is being used for rendering
 */

QOpenGLContext *QSGMaterialShader::RenderState::context() const
{
    return static_cast<const QSGRenderer *>(m_data)->glContext();
}


#ifndef QT_NO_DEBUG
static int qt_material_count = 0;

static void qt_print_material_count()
{
    qDebug("Number of leaked materials: %i", qt_material_count);
    qt_material_count = -1;
}
#endif

/*!
    \class QSGMaterialType
    \brief The QSGMaterialType class is used as a unique type token in combination with QSGMaterial.

    It serves no purpose outside the QSGMaterial::type() function.
 */

/*!
    \class QSGMaterial
    \brief The QSGMaterial class encapsulates rendering state for a shader program.

    The QSGMaterial and QSGMaterialShader subclasses 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 to used to render the geometry.

    The QSGMaterial has two virtual functions that both need to be implemented.
    The function type() should return a unique instance for all instances of a
    specific subclass. The createShader() function should return a new instance
    of QSGMaterialShader, specific to the subclass of QSGMaterial.

    A minimal QSGMaterial implementation could look like this:
    \code
        class Material : public QSGMaterial
        {
        public:
            QSGMaterialType *type() const { static QSGMaterialType type; return &type; }
            QSGMaterialShader *createShader() const { return new Shader; }
        };
    \endcode

    \warning Instances of QSGMaterial belongs to the Scene Graph rendering thread,
    and cannot be used from the GUI thread.
 */

QSGMaterial::QSGMaterial()
    : m_flags(0)
{
#ifndef QT_NO_DEBUG
    ++qt_material_count;
    static bool atexit_registered = false;
    if (!atexit_registered) {
        atexit(qt_print_material_count);
        atexit_registered = true;
    }
#endif
}

QSGMaterial::~QSGMaterial()
{
#ifndef QT_NO_DEBUG
    --qt_material_count;
    if (qt_material_count < 0)
        qDebug("Material destroyed after qt_print_material_count() was called.");
#endif
}



/*!
    \enum QSGMaterial::Flag

    \value Blending Set this flag to true if the material requires GL_BLEND to be
    enabled during rendering.
 */



/*!
    Sets the flags \a flags on this material if \a on is true;
    otherwise clears the attribute.
*/

void QSGMaterial::setFlag(Flags flags, bool on)
{
    if (on)
        m_flags |= flags;
    else
        m_flags &= ~flags;
}



/*!
    Compares this material to \a other and returns 0 if they are equal; -1 if
    this material should sort before \a other and 1 if \a other should sort
    before.

    The scene graph can reorder geometry nodes to minimize state changes.
    The compare function is called during the sorting process so that
    the materials can be sorted to minimize state changes in each
    call to QSGMaterialShader::updateState().

    The this pointer and \a other is guaranteed to have the same type().
 */

int QSGMaterial::compare(const QSGMaterial *other) const
{
    Q_ASSERT(other && type() == other->type());
    return qint64(this) - qint64(other);
}



/*!
    \fn QSGMaterialType QSGMaterial::type() const

    This function is called by the scene graph to return a unique instance
    per subclass.
 */



/*!
    \fn QSGMaterialShader *QSGMaterial::createShader() const

    This function returns a new instance of a the QSGMaterialShader
    implementatation used to render geometry for a specifc implementation
    of QSGMaterial.

    The function will be called only once for each material type that
    exists in the scene graph and will be cached internally.
*/


QT_END_NAMESPACE