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++ // Copyright (C) 2016 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
++
++ #include "squircle.h"
++
++ #include <QtQuick/qquickwindow.h>
++ #include <QOpenGLShaderProgram>
++ #include <QOpenGLContext>
++ #include <QtCore/QRunnable>
++
++ //! [7]
++ Squircle::Squircle()
++ : m_t(0)
++ , m_renderer(nullptr)
++ {
++ connect(this, &QQuickItem::windowChanged, this, &Squircle::handleWindowChanged);
++ }
++ //! [7]
++
++ //! [8]
++ void Squircle::setT(qreal t)
++ {
++ if (t == m_t)
++ return;
++ m_t = t;
++ emit tChanged();
++ if (window())
++ window()->update();
++ }
++ //! [8]
++
++ //! [1]
++ void Squircle::handleWindowChanged(QQuickWindow *win)
++ {
++ if (win) {
++ connect(win, &QQuickWindow::beforeSynchronizing, this, &Squircle::sync, Qt::DirectConnection);
++ connect(win, &QQuickWindow::sceneGraphInvalidated, this, &Squircle::cleanup, Qt::DirectConnection);
++ //! [1]
++ //! [3]
++ // Ensure we start with cleared to black. The squircle's blend mode relies on this.
++ win->setColor(Qt::black);
++ }
++ }
++ //! [3]
++
++ //! [6]
++ void Squircle::cleanup()
++ {
++ delete m_renderer;
++ m_renderer = nullptr;
++ }
++
++ class CleanupJob : public QRunnable
++ {
++ public:
++ CleanupJob(SquircleRenderer *renderer) : m_renderer(renderer) { }
++ void run() override { delete m_renderer; }
++ private:
++ SquircleRenderer *m_renderer;
++ };
++
++ void Squircle::releaseResources()
++ {
++ window()->scheduleRenderJob(new CleanupJob(m_renderer), QQuickWindow::BeforeSynchronizingStage);
++ m_renderer = nullptr;
++ }
++
++ SquircleRenderer::~SquircleRenderer()
++ {
++ delete m_program;
++ }
++ //! [6]
++
++ //! [9]
++ void Squircle::sync()
++ {
++ if (!m_renderer) {
++ m_renderer = new SquircleRenderer();
++ connect(window(), &QQuickWindow::beforeRendering, m_renderer, &SquircleRenderer::init, Qt::DirectConnection);
++ connect(window(), &QQuickWindow::beforeRenderPassRecording, m_renderer, &SquircleRenderer::paint, Qt::DirectConnection);
++ }
++ m_renderer->setViewportSize(window()->size() * window()->devicePixelRatio());
++ m_renderer->setT(m_t);
++ m_renderer->setWindow(window());
++ }
++ //! [9]
++
++ //! [4]
++ void SquircleRenderer::init()
++ {
++ if (!m_program) {
++ QSGRendererInterface *rif = m_window->rendererInterface();
++ Q_ASSERT(rif->graphicsApi() == QSGRendererInterface::OpenGL);
++
++ initializeOpenGLFunctions();
++
++ const float values[] = { -1, -1, 1, -1, -1, 1, 1, 1 };
++
++ m_vbo.create();
++ m_vbo.bind();
++ m_vbo.allocate(values, sizeof(values));
++
++ glEnableVertexAttribArray(0);
++ glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(GLfloat), nullptr);
++
++ m_program = new QOpenGLShaderProgram();
++ m_program->addCacheableShaderFromSourceCode(QOpenGLShader::Vertex,
++ "attribute highp vec4 vertices;"
++ "varying highp vec2 coords;"
++ "void main() {"
++ " gl_Position = vertices;"
++ " coords = vertices.xy;"
++ "}");
++ m_program->addCacheableShaderFromSourceCode(QOpenGLShader::Fragment,
++ "uniform lowp float t;"
++ "varying highp vec2 coords;"
++ "void main() {"
++ " lowp float i = 1. - (pow(abs(coords.x), 4.) + pow(abs(coords.y), 4.));"
++ " i = smoothstep(t - 0.8, t + 0.8, i);"
++ " i = floor(i * 20.) / 20.;"
++ " gl_FragColor = vec4(coords * .5 + .5, i, i);"
++ "}");
++
++ m_program->bindAttributeLocation("vertices", 0);
++ m_program->link();
++
++ }
++ }
++
++ //! [4] //! [5]
++ void SquircleRenderer::paint()
++ {
++ // Play nice with the RHI. Not strictly needed when the scenegraph uses
++ // OpenGL directly.
++ m_window->beginExternalCommands();
++
++ m_vbo.bind();
++ m_program->bind();
++ m_program->setUniformValue("t", (float)m_t);
++
++ glEnableVertexAttribArray(0);
++ glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(GLfloat), nullptr);
++
++ glViewport(0, 0, m_viewportSize.width(), m_viewportSize.height());
++
++ glDisable(GL_DEPTH_TEST);
++
++ glEnable(GL_BLEND);
++ glBlendFunc(GL_SRC_ALPHA, GL_ONE);
++
++ glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
++
++ glDisableVertexAttribArray(0);
++ m_program->release();
++
++ m_window->endExternalCommands();
++ }
++ //! [5]