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50
51#include "background_renderer.h"
52
53#include <qmath.h>
54#include <QFileInfo>
55#include <QTime>
56
57#include <QOpenGLShaderProgram>
58#include <QOpenGLContext>
59#include <QOpenGLFunctions>
60
61#include <math.h>
62
63static const char vertex_shader[] =
64 "attribute highp vec3 vertexCoord;"
65 "void main() {"
66 " gl_Position = vec4(vertexCoord,1.0);"
67 "}";
68
69static const char fragment_shader[] =
70 "void main() {"
71 " gl_FragColor = vec4(0.0,1.0,0.0,1.0);"
72 "}";
73
74static const float vertices[] = { -1, -1, 0,
75 -1, 1, 0,
76 1, -1, 0,
77 1, 1, 0 };
78
79FragmentToy::FragmentToy(const QString &fragmentSource, QObject *parent)
80 : QObject(parent)
81 , m_recompile_shaders(true)
82{
83 if (QFile::exists(fileName: fragmentSource)) {
84 QFileInfo info(fragmentSource);
85 m_fragment_file_last_modified = info.lastModified();
86 m_fragment_file = fragmentSource;
87#if QT_CONFIG(filesystemwatcher)
88 m_watcher.addPath(file: info.canonicalPath());
89 QObject::connect(sender: &m_watcher, signal: &QFileSystemWatcher::directoryChanged, receiver: this, slot: &FragmentToy::fileChanged);
90#endif
91 }
92}
93
94FragmentToy::~FragmentToy()
95 = default;
96
97void FragmentToy::draw(const QSize &windowSize)
98{
99 if (!m_program)
100 initializeOpenGLFunctions();
101
102 glDisable(GL_STENCIL_TEST);
103 glDisable(GL_DEPTH_TEST);
104
105 glClearColor(red: 0, green: 0, blue: 0, alpha: 1);
106 glClear(GL_COLOR_BUFFER_BIT);
107 if (!m_vao.isCreated())
108 m_vao.create();
109
110 QOpenGLVertexArrayObject::Binder binder(&m_vao);
111
112 if (!m_vertex_buffer.isCreated()) {
113 m_vertex_buffer.create();
114 m_vertex_buffer.bind();
115 m_vertex_buffer.allocate(data: vertices, count: sizeof(vertices));
116 m_vertex_buffer.release();
117 }
118
119 if (!m_program) {
120 m_program.reset(p: new QOpenGLShaderProgram);
121 m_program->create();
122 m_vertex_shader.reset(p: new QOpenGLShader(QOpenGLShader::Vertex));
123 if (!m_vertex_shader->compileSourceCode(source: vertex_shader)) {
124 qWarning() << "Failed to compile the vertex shader:" << m_vertex_shader->log();
125 }
126 if (!m_program->addShader(shader: m_vertex_shader.get())) {
127 qWarning() << "Failed to add vertex shader to program:" << m_program->log();
128 }
129 }
130
131 if (!m_fragment_shader && m_recompile_shaders) {
132 QByteArray data;
133 if (m_fragment_file.size()) {
134 QFile file(m_fragment_file);
135 if (file.open(flags: QIODevice::ReadOnly)) {
136 data = file.readAll();
137 } else {
138 qWarning() << "Failed to load input file, falling back to default";
139 data = QByteArray::fromRawData(fragment_shader, size: sizeof(fragment_shader));
140 }
141 } else {
142 QFile qrcFile(":/background.frag");
143 if (qrcFile.open(flags: QIODevice::ReadOnly))
144 data = qrcFile.readAll();
145 else
146 data = QByteArray::fromRawData(fragment_shader, size: sizeof(fragment_shader));
147 }
148 if (data.size()) {
149 m_fragment_shader.reset(p: new QOpenGLShader(QOpenGLShader::Fragment));
150 if (!m_fragment_shader->compileSourceCode(source: data)) {
151 qWarning() << "Failed to compile fragment shader:" << m_fragment_shader->log();
152 m_fragment_shader.reset(p: nullptr);
153 }
154 } else {
155 qWarning() << "Unknown error, no fragment shader";
156 }
157
158 if (m_fragment_shader) {
159 if (!m_program->addShader(shader: m_fragment_shader.get())) {
160 qWarning() << "Failed to add fragment shader to program:" << m_program->log();
161 }
162 }
163 }
164
165 if (m_recompile_shaders) {
166 m_recompile_shaders = false;
167
168 if (m_program->link()) {
169 m_vertex_coord_pos = m_program->attributeLocation(name: "vertexCoord");
170 } else {
171 qWarning() << "Failed to link shader program" << m_program->log();
172 }
173
174 }
175
176 if (!m_program->isLinked())
177 return;
178
179 m_program->bind();
180
181 m_vertex_buffer.bind();
182 m_program->setAttributeBuffer(name: "vertexCoord", GL_FLOAT, offset: 0, tupleSize: 3, stride: 0);
183 m_program->enableAttributeArray(name: "vertexCoord");
184 m_vertex_buffer.release();
185
186 m_program->setUniformValue(name: "currentTime", value: (uint) QDateTime::currentMSecsSinceEpoch());
187 m_program->setUniformValue(name: "windowSize", size: windowSize);
188
189 QOpenGLContext::currentContext()->functions()->glDrawArrays(GL_TRIANGLE_STRIP, first: 0, count: 4);
190
191 m_program->release();
192}
193
194void FragmentToy::fileChanged(const QString &path)
195{
196 Q_UNUSED(path);
197 if (QFile::exists(fileName: m_fragment_file)) {
198 QFileInfo fragment_source(m_fragment_file);
199 if (fragment_source.lastModified() > m_fragment_file_last_modified) {
200 m_fragment_file_last_modified = fragment_source.lastModified();
201 m_recompile_shaders = true;
202 if (m_program) {
203 m_program->removeShader(shader: m_fragment_shader.get());
204 m_fragment_shader.reset(p: nullptr);
205 }
206 }
207 } else {
208 m_recompile_shaders = true;
209 if (m_program) {
210 m_program->removeShader(shader: m_fragment_shader.get());
211 m_fragment_shader.reset(p: nullptr);
212 }
213 }
214}
215

source code of qtbase/examples/opengl/qopenglwindow/background_renderer.cpp