cuberenderer.cpp Example File | Qt Quick 5.12.9

- Qt 5.12
- Qt Quick
- QQuickRenderControl Example
- cuberenderer.cpp Example File
- Qt 5.12.9 Reference Documentation

# cuberenderer.cpp Example File

rendercontrol/cuberenderer.cpp

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     #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(nullptr),
           m_program(nullptr),
           m_vbo(nullptr),
           m_vao(nullptr),
           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->addCacheableShaderFromSourceCode(QOpenGLShader::Vertex, vertexShaderSource);
         m_program->addCacheableShaderFromSourceCode(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, nullptr);
         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);
     }