Method paintGL

compute/example/resize_image.cpp:162–206

}

void ImageWidget::paintGL()
{
    float w = width();
    float h = height();

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0.0, w, 0.0, h, -1.0, 1.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    // setup the resize kernel
    compute::kernel kernel(program_, "resize_image");
    kernel.set_arg(0, image_);
    kernel.set_arg(1, sampler_);
    kernel.set_arg(2, cl_texture_);

    // acquire the opengl texture so it can be used in opencl
    compute::opengl_enqueue_acquire_gl_objects(1, &cl_texture_.get(), queue_);

    // execute the resize kernel
    const size_t global_work_offset[] = { 0, 0 };
    const size_t global_work_size[] = { size_t(width()), size_t(height()) };

    queue_.enqueue_nd_range_kernel(
        kernel, 2, global_work_offset, global_work_size, 0
    );

    // release the opengl texture so it can be used by opengl
    compute::opengl_enqueue_release_gl_objects(1, &cl_texture_.get(), queue_);

    // ensure opencl is finished before rendering in opengl
    queue_.finish();

    // draw a single quad with the resized image texture
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, gl_texture_);

    glBegin(GL_QUADS);
    glTexCoord2f(0, 0); glVertex2f(0, 0);
    glTexCoord2f(0, 1); glVertex2f(0, h);
    glTexCoord2f(1, 1); glVertex2f(w, h);
    glTexCoord2f(1, 0); glVertex2f(w, 0);
    glEnd();
}

// the resize image example demonstrates how to interactively resize a
// 2D image and display it using OpenGL. a image sampler is used to perform