Gnome Flow Users Guide

4. Creating New Objects

As of version 0.9.12, Gnome Flow is able to read object data from various graphic formats: PNG, XPM, JPEG, TIFF, PNM, RAS, BMP and GIF should all work. This feature was added because of the lack of a capable object editor. Now you can create new objects in your favourite drawing program!

There are however some restrictions that apply, when loading objects from graphic files:

  1. The image should be 200x100 pixels in size (WIDTHxHEIGHT). It will be cropped if it's larger and probably crash the program if smaller.
  2. Remember that gflow only calculates flows around symmetric objects - draw only the upper half of your objects!
  3. Make the background black ie. #000000 hex - anything else than black will be regarded as part of an object.
  4. For the same reason, it is a good idea to convert the image to indexed with two colors.

These restrictions will be removed in time.
When loading objects from a graphic file, the data is mirrored in Y, which means that you should draw the objects as if you were drawing in a normal coordinate system - (0,0) is the lower-left corner!

Alternative Way to create objects

NOTE: If you have any possibility to draw your objects using the previously described method, please do so!

If you for some reason wish, you can use the accompaning gfdedit program to create objects that can be used by Gnome Flow. The gfdedit program is a very primitive editor, but it can do the job for now (actually gfdedit is just the scribble-simple program equipped with a Save and Quit button).
VERY IMPORTANT: Because the object(s) have to be symmetric, you can only draw one half of the object(s). In Gnome Flow your objects will allways be mirrored. Furthermore, in gfdedit the Y axis begins at the top of the image (that is not the case for Gnome Flow).
So if you want to draw a cylinder and a plate as objects, you draw something like

gfdedit screenshot

and this will look like (internally) in Gnome Flow as

intern representation

On the contrary, Gnome Flow displays only the upper half of the objects. The reason for this is lazyness and lack of time!
When you are done, you can save the object by pressing Save. You should save the file with gfd extension.

If you decide to draw your object some other way, please be aware of that there is no scaling in Gnome Flow, som the system must be 200x100 pixels in size.

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