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openGLPlotLive

openGLPlotter provides a means to plot large amounts of quickly updated data in an OpenGL context. This can be a window created specifically for the plotter, or to embed in another OpenGL window. Originally this was created to enable debugging of another OpenGL project, where the bug required visualising the path of a vehicle in 60 fps. It may be useful for similar purposes, or for those wanting to embed a graphing library in their code, using c++.

What can it do

Plot simple data in realtime. Current data formats:

  • Vector of pt2D - custom (x,y) point structure
  • Vector of consecutive x,y values. e.g. {x1,y1,x2,y2,...,xn,yn}
  • Vector of 2-vector x,y pairs. e.g. {vector {x1,y1}, vector {x2,y2}, ... vector<float {xn,yn}}

Simple Plots

Window Setup

To create a window for plotting, you will need the following

// Window Size
int windowWidth  = 800;
int windowHeight = 800;

// Init GLFW
std::shared_ptr<GLPL::IWindow> window = std::shared_ptr<GLPL::IWindow>(new GLPL::Window(windowWidth, windowHeight));
std::shared_ptr<GLPL::Window> window2 = std::dynamic_pointer_cast<GLPL::Window>(window);

Create Data

You will need some data to plot, currently it needs to adhere to one of three formats. Plans for the future is to enable more formats to be added. For example, creating data in the vector format, with all the data to be plotted from the first frame.

// Graph 2
vector<pt2D> data2;
for(int i=-1000; i<1000; i++) {
	pt2D pt2;
	float x = i/1000.0;
	pt2.x = x;
	pt2.y = -x-1;
	data2.push_back(pt2);
}

You can also initialise data, and create it as the plot is being draw. For example for data of the format vector<vector>.

// Graph 5 - Vector of Vectors
vector<vector<float>> data5;

Create Plot

You will need to create a plot to add the lines to. Creating a plot that starts at x=0.0, y=0.25 (proportion of the window), and has width and height of 0.75 the respective lengths,

// Create Plot
GLPL::Plot myplot(0.0, 0.25, 0.75, 0.75, window);
// Create Lines
Line2Dpts line2(&data2);
Line2DVecVec line5(&data5);
// Add lines to axes
myplot.axes.addLine(&line2);
myplot.axes.addLine(&line5);

The Drawing Loop

To draw in real time you will require a drawing loop. The following draws the plot, axes and lines, updates the plot data for plot 5 and prepares the plot for the next draw call.

while(!glfwWindowShouldClose(window->getWindow())) {
	// Pre-loop draw
	window2->preLoopDraw(true);

	// Update Graph 5
	i -= 10;
	for(int j=0; j < 10; j++) {
		vector<float> tempVec = {i/1000.0, 0.5*i/1000.0};
		data5.push_back(tempVec);
		i += 1;
	}
	line5.updateInternalData();

	// Draw Plot
	myplot.Draw();

	// Post-loop draw
	window2->postLoopDraw();
}

After the draw loop, handle closing the window

// Close Window
glfwTerminate();

Shader Directory

When including in another project, you'll need to copy the Shader directory to the root of your project. Provided the openGLPlotLive directory is in the top level of your project, this can be done in cmake with the following,

add_custom_command(TARGET ${PROJECT_NAME} PRE_BUILD COMMAND ${CMAKE_COMMAND} -E copy_directory ${PROJECT_SOURCE_DIR}/../openGLPlotLive/Shaders $<TARGET_FILE_DIR:${PROJECT_NAME}>/Shaders)

Dependencies

Automated Install

A few scripts have been created to automate the installation process. In the event these fail, you may have to compile the dependencies manually. Support for Windows systems have been removed as of 1/2/2017. If may still be possible to complie on Windows, check the Windows-old-store branch for a bit of help for installation of some of the required packages.

Linux (Ubuntu)

On Ubuntu these dependencies can be installed by running

sudo chmod +x installDependencies.sh
./installDependenciesUbuntu.txt

Manual Install

Linux (Ubuntu)

  • Building Dependencies

    • cmake
     sudo apt-get install cmake

  • GLFW (multi-platform library for OpenGL)

     sudo apt-get install xorg-dev libglu1-mesa-dev
    • Navigate to the glfw root directory and use cmake
     cmake -G "Unix Makefiles"
 make -j4
 sudo make install

  • GLM (The OpenGL Mathematics Library)

     cd <glm_root_dir>
 sudo cp -r glm /usr/local/include/

  • FreeType - Font Rendering Library

     sudo cp -r include/* /usr/local/include

    Please DO NOT run ./configure on a system running the Unity window manager, as this will most likely break Unity.

Compiling

A CMakeLists.txt file is included for compiling with Cmake. This should work for systems running Ubuntu. Navigate to the build directory and remove any old CMakeFiles

cd build
rm -r *

Run cmake to generate a makefile.

cmake ../                           # Linux
cmake -G "MinGW Makefiles" ../      # Windows

Compile the program.

make -j4

There are a number of different make targets.

Target Description Output (build directory)
all Make all the targets below
examplePlot Make the example plot window apps/examplePlot
openGLPlotLive Make the shared library libopenGLPlotLive.so src/libOpenGLPlotLive.so
docs Makes both the doxygen and sphinx documentation docs/doxygen/html/index.html,
docs/sphinx/index.html
tests Make the test suite runner using gtest tests/openGLPlotLive-proj_tests

Debugging

To enable debugging, when running cmake, enable the debugging flag.

cmake -DCMAKE_BUILD_TYPE=Debug

Documentation

There are two ways to generate documentation, with the latter requiring the former.

  • Using Doxygen
  • Using Sphinx with Breathe and Doxygen

Doxygen

To generate doxygen documentation, provided doxygen is in your path, run the following

cd build
rm -rf *

cmake ../                           # Linux
cmake -G "MinGW Makefiles" ../      # Windows

make doxygen

The main page is then generated at <project_root>/build/docs/html/index.html.

Sphinx

Sphinx documentation requires first generating Doxygen documentation, then using the outputted xml with Breathe, to generated the sphinx documentation.

# First generate doxygen documentation as above
cd build
make sphinx

Runnning an Example

An example binary is created, examplePlot. To run this

cd build/apps
./examplePlot

Controls

When autoscaling is disabled, the following controls allows the user to manipulate the axes area:

Control Input Description
Scroll Wheel Zooms the axes in and out
Right Click & Drag Zoom the x & y axes at different scales, based on the drag distance
Left Click & Drag Pan the axes left, right, up or down
Left Click, hold Shift Key & Drag Drag a zoom box, that will zoom to the extents of the box on release
Middle Click & Drag Drag a zoom box, that will zoom to the extents of the box on release
Spacebar Iterates through plotables in the view, when the view is hovered

Compiling an Eclipse Project

To generate an Eclipse project, from the root directory,

cd build
rm -r CMakeFiles/
cmake -G "Eclipse CDT4 - Unix Makefiles" ../src

Then import the project into Eclipse using File >> Import >> General >> Existing Projects into Workspace. Click next and set the root directory to /openGLMap/build. Click Finish. The project can now be built with Eclipse using the 'all' Build Target. The source files will be inside the "[Source Directory]" and are linked to their actual counterpats.

Debugging

A useful tool for debugging anything at the opengl level is qrenderdoc - https://github.com/baldurk/renderdoc

Tests with googletest

Some simple tests have been written for debugging purposes. These use the googletest framework. To compile and run the tests,

cd build
make tests -j4
cd tests
./openGLPlotLive-proj_tests