- Qt 5.5
- Qt Quick
- QQuickRenderControl Example
- cuberenderer.cpp Example File
- Qt 5.5.1 Reference Documentation

# cuberenderer.cpp Example File

rendercontrol/cuberenderer.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
    **
    ** "Redistribution and use in source and binary forms, with or without
    ** modification, are permitted provided that the following conditions are
    ** met:
    **   * Redistributions of source code must retain the above copyright
    **     notice, this list of conditions and the following disclaimer.
    **   * Redistributions in binary form must reproduce the above copyright
    **     notice, this list of conditions and the following disclaimer in
    **     the documentation and/or other materials provided with the
    **     distribution.
    **   * Neither the name of The Qt Company Ltd nor the names of its
    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
    **
    **
    ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
    **
    ** $QT_END_LICENSE$
    **
    ****************************************************************************/

    #include "cuberenderer.h"
    #include <QOpenGLContext>
    #include <QOpenGLFunctions>
    #include <QOpenGLShaderProgram>
    #include <QOpenGLVertexArrayObject>
    #include <QOpenGLBuffer>
    #include <QOpenGLVertexArrayObject>
    #include <QOffscreenSurface>
    #include <QWindow>

    CubeRenderer::CubeRenderer(QOffscreenSurface *offscreenSurface)
        : m_offscreenSurface(offscreenSurface),
          m_context(0),
          m_program(0),
          m_vbo(0),
          m_vao(0),
          m_matrixLoc(0)
    {
    }

    CubeRenderer::~CubeRenderer()
    {
        // Use a temporary offscreen surface to do the cleanup.
        // There may not be a native window surface available anymore at this stage.
        m_context->makeCurrent(m_offscreenSurface);

        delete m_program;
        delete m_vbo;
        delete m_vao;

        m_context->doneCurrent();
        delete m_context;
    }

    void CubeRenderer::init(QWindow *w, QOpenGLContext *share)
    {
        m_context = new QOpenGLContext;
        m_context->setShareContext(share);
        m_context->setFormat(w->requestedFormat());
        m_context->create();
        if (!m_context->makeCurrent(w))
            return;

        QOpenGLFunctions *f = m_context->functions();
        f->glClearColor(0.0f, 0.1f, 0.25f, 1.0f);
        f->glViewport(0, 0, w->width() * w->devicePixelRatio(), w->height() * w->devicePixelRatio());

        static const char *vertexShaderSource =
            "attribute highp vec4 vertex;\n"
            "attribute lowp vec2 coord;\n"
            "varying lowp vec2 v_coord;\n"
            "uniform highp mat4 matrix;\n"
            "void main() {\n"
            "   v_coord = coord;\n"
            "   gl_Position = matrix * vertex;\n"
            "}\n";
        static const char *fragmentShaderSource =
            "varying lowp vec2 v_coord;\n"
            "uniform sampler2D sampler;\n"
            "void main() {\n"
            "   gl_FragColor = vec4(texture2D(sampler, v_coord).rgb, 1.0);\n"
            "}\n";
        m_program = new QOpenGLShaderProgram;
        m_program->addShaderFromSourceCode(QOpenGLShader::Vertex, vertexShaderSource);
        m_program->addShaderFromSourceCode(QOpenGLShader::Fragment, fragmentShaderSource);
        m_program->bindAttributeLocation("vertex", 0);
        m_program->bindAttributeLocation("coord", 1);
        m_program->link();
        m_matrixLoc = m_program->uniformLocation("matrix");

        m_vao = new QOpenGLVertexArrayObject;
        m_vao->create();
        QOpenGLVertexArrayObject::Binder vaoBinder(m_vao);

        m_vbo = new QOpenGLBuffer;
        m_vbo->create();
        m_vbo->bind();

        GLfloat v[] = {
            -0.5, 0.5, 0.5, 0.5,-0.5,0.5,-0.5,-0.5,0.5,
            0.5, -0.5, 0.5, -0.5,0.5,0.5,0.5,0.5,0.5,
            -0.5, -0.5, -0.5, 0.5,-0.5,-0.5,-0.5,0.5,-0.5,
            0.5, 0.5, -0.5, -0.5,0.5,-0.5,0.5,-0.5,-0.5,

            0.5, -0.5, -0.5, 0.5,-0.5,0.5,0.5,0.5,-0.5,
            0.5, 0.5, 0.5, 0.5,0.5,-0.5,0.5,-0.5,0.5,
            -0.5, 0.5, -0.5, -0.5,-0.5,0.5,-0.5,-0.5,-0.5,
            -0.5, -0.5, 0.5, -0.5,0.5,-0.5,-0.5,0.5,0.5,

            0.5, 0.5,  -0.5, -0.5, 0.5,  0.5,  -0.5,  0.5,  -0.5,
            -0.5,  0.5,  0.5,  0.5,  0.5,  -0.5, 0.5, 0.5,  0.5,
            -0.5,  -0.5, -0.5, -0.5, -0.5, 0.5,  0.5, -0.5, -0.5,
            0.5, -0.5, 0.5,  0.5,  -0.5, -0.5, -0.5,  -0.5, 0.5
        };
        GLfloat texCoords[] = {
            0.0f,0.0f, 1.0f,1.0f, 1.0f,0.0f,
            1.0f,1.0f, 0.0f,0.0f, 0.0f,1.0f,
            1.0f,1.0f, 1.0f,0.0f, 0.0f,1.0f,
            0.0f,0.0f, 0.0f,1.0f, 1.0f,0.0f,

            1.0f,1.0f, 1.0f,0.0f, 0.0f,1.0f,
            0.0f,0.0f, 0.0f,1.0f, 1.0f,0.0f,
            0.0f,0.0f, 1.0f,1.0f, 1.0f,0.0f,
            1.0f,1.0f, 0.0f,0.0f, 0.0f,1.0f,

            0.0f,1.0f, 1.0f,0.0f, 1.0f,1.0f,
            1.0f,0.0f, 0.0f,1.0f, 0.0f,0.0f,
            1.0f,0.0f, 1.0f,1.0f, 0.0f,0.0f,
            0.0f,1.0f, 0.0f,0.0f, 1.0f,1.0f
        };

        const int vertexCount = 36;
        m_vbo->allocate(sizeof(GLfloat) * vertexCount * 5);
        m_vbo->write(0, v, sizeof(GLfloat) * vertexCount * 3);
        m_vbo->write(sizeof(GLfloat) * vertexCount * 3, texCoords, sizeof(GLfloat) * vertexCount * 2);
        m_vbo->release();

        if (m_vao->isCreated())
            setupVertexAttribs();
    }

    void CubeRenderer::resize(int w, int h)
    {
        m_proj.setToIdentity();
        m_proj.perspective(45, w / float(h), 0.01f, 100.0f);
    }

    void CubeRenderer::setupVertexAttribs()
    {
        m_vbo->bind();
        m_program->enableAttributeArray(0);
        m_program->enableAttributeArray(1);
        m_context->functions()->glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
        m_context->functions()->glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0,
                                                      (const void *)(36 * 3 * sizeof(GLfloat)));
        m_vbo->release();
    }

    void CubeRenderer::render(QWindow *w, QOpenGLContext *share, uint texture)
    {
        if (!m_context)
            init(w, share);

        if (!m_context->makeCurrent(w))
            return;

        QOpenGLFunctions *f = m_context->functions();
        f->glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        if (texture) {
            f->glBindTexture(GL_TEXTURE_2D, texture);
            f->glFrontFace(GL_CW); // because our cube's vertex data is such
            f->glEnable(GL_CULL_FACE);
            f->glEnable(GL_DEPTH_TEST);

            m_program->bind();
            QOpenGLVertexArrayObject::Binder vaoBinder(m_vao);
            // If VAOs are not supported, set the vertex attributes every time.
            if (!m_vao->isCreated())
                setupVertexAttribs();

            static GLfloat angle = 0;
            QMatrix4x4 m;
            m.translate(0, 0, -2);
            m.rotate(90, 0, 0, 1);
            m.rotate(angle, 0.5, 1, 0);
            angle += 0.5f;

            m_program->setUniformValue(m_matrixLoc, m_proj * m);

            // Draw the cube.
            f->glDrawArrays(GL_TRIANGLES, 0, 36);
        }

        m_context->swapBuffers(w);
    }