QML DropShadow is very slow

QML DropShadow is an interesting effect that acts in a very simple way. It works fine in my application and produces the following result:

QML DropShadow is very slow

The only disadvantage of DropShadow effect is that is slows down my application from 60 FPS to 30 FPS on Android Phone. The following code demonstrates how I use it with StackView:

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How to start Lines 3D game in auto-play mode.

Lines 3D is a fun logical game with different difficulty levels.  While “Beginner” level is an easy to play relaxing game, the “Professional” and “Expert” levels are good exercises for your brain where you can apply your knowledge in the area of the probability theory. There is also some specific “Baby” level for babies, allowing them to move balls and do not worry about the result.

For IT professionals, there is auto-play mode for testing the application performance and stability. To start Lines 3D game in auto-play mode first install Lines 3D game from Windows Store, start it and select the following game options:

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Lines 3D application structure (Windows Store version)

Lines 3D game is a UWP application based on “XAML App for OpenGL ES (Universal Windows)VS2015 project template (written in C++/VS2015 using OpenGL ES 2.0 and elements of OpenGL 3.0). You can install Lines 3D  from Windows Store and play for free, or at least see the game screenshots.

Main components

Game logic and OpenGL rendering engine in Lines 3D are cross-platform. Their code uses STL, OpenGL and abstract C++ interfaces for doing the following tasks:

  • Loading sounds from wav files and playing them with different speed and volume.
  • Loading textures from PNG images (this code uses Windows API, but probably it can be made cross-platform).
  • Logging game events, such as “game over” to the Windows Store. They used to collect statistics on what game levels the users play and what score they get. The possible application crashes (unhandled exceptions and memory failures) and internal errors (like file not found, etc.) are also logged to the Windows Store.
  • Accessing application installation path and application data path in the file system.

All the graphic controls, including the main windows, application bar (main menu), dialogs, message boxes and advertising are written using XAML and Windows-specific code.

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Compiling GDAL on Ubuntu Linux with SQLite and MySQL support

Fist install MySQL client libraries and check their location:

apt-get install libmysqlclient-dev
find / -name '*libmysqlclient*'

Then install SQLite:

sudo apt-get install sqlite3 libsqlite3-dev

Extract GDAL sources and configure supported modules (MySQL and SQLite are not compiled by default, so we need to specify them explicitly):

unzip gdal211.zip
cd gdal-2.1.1/
./configure --with-sqlite3 --with-mysql

this will output “MySQL support: yes” and “SQLite support: yes” along with other information.

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Drawing a transparent image with OpenGL ES in a UWP XAML app

In my previous post Testing XAML App for OpenGL ES on Windows 10 Mobile Device I described the changes I made to UWP application based on “XAML App for OpenGL ES (Universal Windows)” template to demonstrate some strange effect related to the transparency of the image drawn with OpenGL ES in SwapChainPanel. But I did yet another experiment with this application and got some beautiful pictures that demonstrate what happens if I make the scene completely transparent with the following code:

void SimpleRenderer::Draw()
{
    glEnable(GL_DEPTH_TEST);
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    ...
}

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Testing XAML App for OpenGL ES on Windows 10 Mobile Device

Today I played a bit with a UWP application based on “XAML App for OpenGL ES (Universal Windows)” template and realized that there is some specific bug probably related to the interaction between SwapChainPanel and OpenGL surface. First, I made the cube transparent by changing two lines of code in the vertex shader:

const std::string vs = STRING
(
    uniform mat4 uModelMatrix;
    uniform mat4 uViewMatrix;
    uniform mat4 uProjMatrix;
    attribute vec4 aPosition;
    attribute vec3 aColor;
    varying vec4 vColor;
    void main()
    {
        gl_Position = uProjMatrix * uViewMatrix * uModelMatrix * aPosition;
        vColor = vec4(aColor, 0.1);
    }
);

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UWP Application beta testing

There are two main options in the Windows Store how to hide the app from public but make it available for specific users or beta testers: Package flights and Promotional codes. Below I briefly describe how I used Promotional codes with my app by the example of Lines 3D game.

According to the Microsoft guide, in my submission on the Pricing and availability page in Distribution and visibility I chosen Hide this app and prevent acquisition. Customers with a promotional code can still download it on Windows 10 devices. Then I generated one promotional code and got so called “Redeemable URL” or the app activation link in other words.

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How to compile QT with VS2015 and GCC

Below I provided a simple step by step instruction on how to compile QT 5.7 with VS2015 assuming you already have VS2015 and Git client installed on your Windows machine.

Install Perl, Python and Ruby.

To get QT 5.7 sources open Git Bash and run the following command (the repository has some submodules, so “recursive” option is required), see the list of possible clone here at the bottom of the page:

git clone --recursive https://github.com/qtproject/qt5.git --branch 5.7

Create a bat file called configureqt.bat with the following content:

set PATH=%PATH%;"C:\Program Files (x86)\Portable\ruby-2.3.0-i386-mingw32\bin";C:\Perl\bin;C:\Python27
D:
cd D:\Repos\qt5\
set _ROOT=D:\Repos\qt5
set PATH=%_ROOT%\qtbase\bin;%_ROOT%\gnuwin32\bin;%PATH%
set QMAKESPEC=win32-msvc2015
set _ROOT=
configure -debug -nomake examples -opensource

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Using OpenGL 3.0 with MSOpenTech ANGLE

Typically ANGLE library is used with OpenGL 2.0, but I successfully tried to enable OpenGL 3.0:

const EGLint contextAttributes[] = 
{ 
    EGL_CONTEXT_CLIENT_VERSION, 3, 
    EGL_NONE
};

and used some OpenGL 3.0 features in my Universal Windows App. But today I tried to compile my application with the new version of ANGLE library and got EGL_BAD_CONFIG error while creating the OpenGL context. The source code that returns this error checks some EGL_OPENGL_ES3_BIT_KHR that is not set in the new version:

if (clientMajorVersion == 3 && !(configuration->conformant & EGL_OPENGL_ES3_BIT_KHR))
{
    return Error(EGL_BAD_CONFIG);
}

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Debugging a C++ application on an Android device with VS2015 on Windows 10

VS2015 has an exciting ability to debug a C++ application on Android Emulator, but in this article I will talk about no less exciting and more time expensive ability to debug a C++ application on a real Android device. The first thing we need to spend the time with is figuring out how to enable USB debugging mode on our Android device. On my ASUS Zenfone I need to go to Settings->About->Software Information and tap on Build Number 7 times, after that I have USB debugging check box in Settings->Developer Options that I should tap as well:

enabling USB debugging mode on Android device USB debugging mode on Android device

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