Graphics on Raspberry Pi with Qt 5

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Agenda • OpenGL and Gt • Cross-compiling Qt 5.6 • Next generation 3D rendering

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Me • Call me TP • Follow @uranusjr • https://uranusjr.com

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www. .com

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Why Qt? • OpenGL is tedious • Long history of integration • Qt Quick and QML • Continuous improvements

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#include #include int main(int argc, char *argv[]) { QApplication app(argc, argv); QWidget w; w.show(); return app.exec(); }

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How? • Widgets • Put things inside a widget • Put widgets in a window • Show windows in an application

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How? • Widgets • Add common GUI controls • Put widgets in a window • Show windows in an application

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How? • Widgets • Draw things with OpenGL • Put widgets in a window • Show windows in an application

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C++ Classes • QOpenGLWidget • QOpenGLContext • QOpenGLFunctions

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#include class MyWidget : public QOpenGLWidget { protected: // One-off settings. virtual void initializeGL(); // Set projection. Called on resizing. virtual void resizeGL(int w, int h); // Do actual OpenGL painting. virtual void paintGL(); }

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/usr/lib/x86_64-linux-gnu/qt5/examples/gui/openglwindow/

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Read the docs. http://doc.qt.io/qt-5/qopenglwidget.html

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Problems? • Legacy QtOpenGL module • Raspbian updates slowly • We want newer Qt

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Cross-Compiling • More up-to-date Qt distribution • Better support for add-on modules • Advanced tuning (if you want to)

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Read the wiki. https://wiki.qt.io/RaspberryPi_Beginners_Guide

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Read my notes. http://bit.ly/rpi-qt5-cross-compile

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Demo

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Qt 3D • Based on OpenGL • Simple C++ or QML usage • Quite powerful

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Qt 3D Canvas • Based on OpenGL • JavaScript API in Qt Quick • Modelled from WebGL • three.js port!