1// Copyright (C) 2016 The Qt Company Ltd.
2// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
3
4#include "qsgmaterial.h"
5#include "qsgrenderer_p.h"
6
7QT_BEGIN_NAMESPACE
8
9#ifndef QT_NO_DEBUG
10bool qsg_material_failure = false;
11bool qsg_test_and_clear_material_failure()
12{
13 bool fail = qsg_material_failure;
14 qsg_material_failure = false;
15 return fail;
16}
17
18void qsg_set_material_failure()
19{
20 qsg_material_failure = true;
21}
22#endif
23
24/*!
25 \group qtquick-scenegraph-materials
26 \title Qt Quick Scene Graph Material Classes
27 \brief classes used to define materials in the Qt Quick Scene Graph.
28
29 This page lists the material classes in \l {Qt Quick}'s
30 \l {scene graph}{Qt Quick Scene Graph}.
31 */
32
33#ifndef QT_NO_DEBUG
34static int qt_material_count = 0;
35
36static void qt_print_material_count()
37{
38 qDebug(msg: "Number of leaked materials: %i", qt_material_count);
39 qt_material_count = -1;
40}
41#endif
42
43/*!
44 \class QSGMaterialType
45 \brief The QSGMaterialType class is used as a unique type token in combination with QSGMaterial.
46 \inmodule QtQuick
47 \ingroup qtquick-scenegraph-materials
48
49 It serves no purpose outside the QSGMaterial::type() function.
50
51 \note All classes with QSG prefix should be used solely on the scene graph's
52 rendering thread. See \l {Scene Graph and Rendering} for more information.
53 */
54
55/*!
56 \class QSGMaterial
57 \brief The QSGMaterial class encapsulates rendering state for a shader program.
58 \inmodule QtQuick
59 \ingroup qtquick-scenegraph-materials
60
61 QSGMaterial and QSGMaterialShader subclasses form a tight relationship. For
62 one scene graph (including nested graphs), there is one unique
63 QSGMaterialShader instance which encapsulates the shaders the scene graph
64 uses to render that material, such as a shader to flat coloring of
65 geometry. Each QSGGeometryNode can have a unique QSGMaterial containing the
66 how the shader should be configured when drawing that node, such as the
67 actual color to used to render the geometry.
68
69 QSGMaterial has two virtual functions that both need to be implemented. The
70 function type() should return a unique instance for all instances of a
71 specific subclass. The createShader() function should return a new instance
72 of QSGMaterialShader, specific to that subclass of QSGMaterial.
73
74 A minimal QSGMaterial implementation could look like this:
75 \code
76 class Material : public QSGMaterial
77 {
78 public:
79 QSGMaterialType *type() const override { static QSGMaterialType type; return &type; }
80 QSGMaterialShader *createShader(QSGRendererInterface::RenderMode) const override { return new Shader; }
81 };
82 \endcode
83
84 See the \l{Scene Graph - Custom Material}{Custom Material example} for an introduction
85 on implementing a QQuickItem subclass backed by a QSGGeometryNode and a custom
86 material.
87
88 \note createShader() is called only once per QSGMaterialType, to reduce
89 redundant work with shader preparation. If a QSGMaterial is backed by
90 multiple sets of vertex and fragment shader combinations, the implementation
91 of type() must return a different, unique QSGMaterialType pointer for each
92 combination of shaders.
93
94 \note All classes with QSG prefix should be used solely on the scene graph's
95 rendering thread. See \l {Scene Graph and Rendering} for more information.
96
97 \sa QSGMaterialShader, {Scene Graph - Custom Material}, {Scene Graph - Two Texture Providers}, {Scene Graph - Graph}
98 */
99
100/*!
101 \internal
102 */
103
104QSGMaterial::QSGMaterial()
105{
106 Q_UNUSED(m_reserved);
107#ifndef QT_NO_DEBUG
108 if (_q_sg_leak_check) {
109 ++qt_material_count;
110 static bool atexit_registered = false;
111 if (!atexit_registered) {
112 atexit(func: qt_print_material_count);
113 atexit_registered = true;
114 }
115 }
116#endif
117}
118
119
120/*!
121 \internal
122 */
123
124QSGMaterial::~QSGMaterial()
125{
126#ifndef QT_NO_DEBUG
127 if (_q_sg_leak_check) {
128 --qt_material_count;
129 if (qt_material_count < 0)
130 qDebug(msg: "Material destroyed after qt_print_material_count() was called.");
131 }
132#endif
133}
134
135
136
137/*!
138 \enum QSGMaterial::Flag
139
140 \value Blending Set this flag to true if the material requires blending to be
141 enabled during rendering.
142
143 \value RequiresDeterminant Set this flag to true if the material relies on
144 the determinant of the matrix of the geometry nodes for rendering.
145
146 \value RequiresFullMatrixExceptTranslate Set this flag to true if the material
147 relies on the full matrix of the geometry nodes for rendering, except the translation part.
148
149 \value RequiresFullMatrix Set this flag to true if the material relies on
150 the full matrix of the geometry nodes for rendering.
151
152 \value NoBatching Set this flag to true if the material uses shaders that are
153 incompatible with the \l{Qt Quick Scene Graph Default Renderer}{scene graph's batching
154 mechanism}. This is relevant in certain advanced usages, such as, directly
155 manipulating \c{gl_Position.z} in the vertex shader. Such solutions are often tied to
156 a specific scene structure, and are likely not safe to use with arbitrary contents in
157 a scene. Thus this flag should only be set after appropriate investigation, and will
158 never be needed for the vast majority of materials. Setting this flag can lead to
159 reduced performance due to having to issue more draw calls. This flag was introduced
160 in Qt 6.3.
161
162 \value CustomCompileStep In Qt 6 this flag is identical to NoBatching. Prefer using
163 NoBatching instead.
164 */
165
166/*!
167 \fn QSGMaterial::Flags QSGMaterial::flags() const
168
169 Returns the material's flags.
170 */
171
172
173
174/*!
175 Sets the flags \a flags on this material if \a on is true;
176 otherwise clears the attribute.
177*/
178
179void QSGMaterial::setFlag(Flags flags, bool on)
180{
181 if (on)
182 m_flags |= flags;
183 else
184 m_flags &= ~flags;
185}
186
187
188
189/*!
190 Compares this material to \a other and returns 0 if they are equal; -1 if
191 this material should sort before \a other and 1 if \a other should sort
192 before.
193
194 The scene graph can reorder geometry nodes to minimize state changes.
195 The compare function is called during the sorting process so that
196 the materials can be sorted to minimize state changes in each
197 call to QSGMaterialShader::updateState().
198
199 The this pointer and \a other is guaranteed to have the same type().
200 */
201
202int QSGMaterial::compare(const QSGMaterial *other) const
203{
204 Q_ASSERT(other && type() == other->type());
205 const qintptr diff = qintptr(this) - qintptr(other);
206 return diff < 0 ? -1 : (diff > 0 ? 1 : 0);
207}
208
209
210
211/*!
212 \fn QSGMaterialType *QSGMaterial::type() const
213
214 This function is called by the scene graph to query an identifier that is
215 unique to the QSGMaterialShader instantiated by createShader().
216
217 For many materials, the typical approach will be to return a pointer to a
218 static, and so globally available, QSGMaterialType instance. The
219 QSGMaterialType is an opaque object. Its purpose is only to serve as a
220 type-safe, simple way to generate unique material identifiers.
221 \code
222 QSGMaterialType *type() const override
223 {
224 static QSGMaterialType type;
225 return &type;
226 }
227 \endcode
228 */
229
230
231
232/*!
233 \fn QSGMaterialShader *QSGMaterial::createShader(QSGRendererInterface::RenderMode renderMode) const
234
235 This function returns a new instance of a the QSGMaterialShader
236 implementation used to render geometry for a specific implementation
237 of QSGMaterial.
238
239 The function will be called only once for each combination of material type and \a renderMode
240 and will be cached internally.
241
242 For most materials, the \a renderMode can be ignored. A few materials may need
243 custom handling for specific render modes. For instance if the material implements
244 antialiasing in a way that needs to account for perspective transformations when
245 RenderMode3D is in use.
246*/
247
248QT_END_NAMESPACE
249

source code of qtdeclarative/src/quick/scenegraph/coreapi/qsgmaterial.cpp