Demo_graph

This example project demonstrates several features of Transd. The project consists of C++ and Transd programs working together. The C++ program calls the Transd program "renderer". The renderer does its job of creating a graph of a function and stores it in a vector. After the job is done the C++ program obtaines the result vector and writes it in a PPM image file.

This project differs from a more simple Demo_tiny project in many aspects and demonstrates many notable points.

The Transd renderer here is called not many times, but only once and does all its job in an internal loop.

The Transd program could be placed in a single file, but for illustrative purposes is separated to several semantic parts:

1. The worker loop (in module1), instantiates the renderer object of Quad class and repeatedly calls its render function.

2. The Quad class definition file which serves as a class library which can be used by other modules (by module1 in this case). The Quad class implements the renderer of the quadratic function graph ( f(x) = x^2 ). In the same way also renderers for linear function, cubic function, etc. could be implemented (or even a ray-tracer renderer of non-mathematical objects).

3. The Export module is located in a separate directory and serves for two purposes. First, it can be considered as a configuration file where users of the program can set various parameters. Second, this module is the data interface between C++ and Transd programs: C++ program has the full read/write access to all the data members of the Export module.

The module import system is observable in the module1 definition. Any module can request import of other class or module, defined in one of the files listed in the assembly description (in the asm.td file). This import request can be denied, however, in accordance with access control rules defined in the imported module. But if the request is fullfilled, the importing module can instantiate objects of imported classes (module1 instantiates an object of the Quad class) and access members of imported modules (module1 uses the vector 'v' from the Export module).

Another Transd feature used here is the Access Control System, which is visible in the declaration of the Export module:

public module Export: {

Which declares all the module's contents as accessible from anywhere. For the Export module this type of access is mandatory, but generally modules can limit access to all or some of their members and can choose for which other modules they grant or restrict access.

How to build

Windows

1. Ensure that the directory 'renderer' from the Demo_graph distribution is writable. Into this directory the output file of the program will be written.

2. Edit the 'main.cpp' file: locate the following line at the top of the file:

std::string workingDir = "Y:\\your\\working\\directory\\"

and change it by specifying the full path of the 'renderer' directory.

3. Build the solution and run the executable. Check the image in the output "graph.ppm" file. PPM image files can be opened e.g. with LibreOffice, GIMP, etc. Report of any issues here: https://github.com/transd-lang/Demo_graph/issues

Linux

To be written...

Result

The result of the program (the graph of the quadratic function) can be seen here: rendered image.

You can try and tweak the renderer's definition in the 'quad.td' file for rendering other images.

All issue reports, questions and ideas are welcome here: https://github.com/transd-lang/Demo_graph/issues