Dev:Source/UI/Command Line

CommandLine

The purpose of this project is to add a whole new power to blender without removing anything which blender currently has. Old blender users will not notice any difference in blender interface, unless they wish to do so.

1. Introduction

First thing to notice is that blender uses fixed keyboard mappings. Every _blender action_ is internally mapped in blender to some keyboard combination.

Now, what will happen if we try to unfix keyboard mapping? First of all we should create a keyboard mapping file. By default it will contain default blender mappings.

1.1. Keyboard mappings

Change the way that keyboard mappings are handled _internally_ by blender. Every _blender action_ must be given a descriptive name (this name becomes a _blender command_), then a key binding is defined in a way: [conditions] [key] [name_of_the_command], for example:

object_mode   g    grab_selection=

Default key bindings will be the ones that blender currently has. Adding any new command to blender will require extending keybindigs.

Commands added by writing user python scripts will be treated equally with _blender commands_. Thus can be assigned a keybinding.

1.2. Introduce a command line

Upon user request a command line will appear and the user will be able to write commands there. Those commands will be just =[name_of_the_command]=. Also a shorter alias could be defined: =[alias] [name_of_the_command]=, for example:

alias         sn     popup_snap_menu
alias         mov    grab_selection

Because every _internal blender action_ can be invoked from command line (by typing _blender command_), it will be possible to write command scripts then feed them to command line. (two possible uses spark to my mind: 1. blender demos - a user launches demo script and watches blender doing everything step by step, 2. automated drawing of models without a GUI)

2. More details - rules for keyboard mapping

2.1. How =.Bkeymap= should look like?

Here should be a full DefaultBkeymap file (still under construction ;). Some excerpts are below:

mode             omod         object_mode
mode             3win         3d_window
mode             osel         object_is_selected
mode             twin         text_edit_window

true             F1           load_file
true             shift-S      popup_snap_menu
omod,3win,osel   f            toggle_face_display
twin             alt-shift-s  select_text_menu

alias            sn           popup_snap_menu

(compare with [1], and with [2])

If a user accidentally destroys this file he would restore it by invoking a command eg.

blender -k > .Bkeymap

2.2. Mapping _blender commands_

Every mapping is in the form: [conditions] [key] [name_of_the_command], where [conditions] is a comma separated list of conditions. All of the conditions must be true for the mapping to take effect.

2.3. Declare =mode= for shorter mapping rules

Writing:

text_edit_window  alt-shift-s  select_text_menu

is a little too long, we will use =mode= command to add more modes:

mode              twin         text_edit_window

now writing twin will be equal to writing text_edit_window, note that this is different than alias. The mode mapping has a scope of .Bkeymap file, while alias has a scope of command line. In fact alias is:

mode              alias        command_line_active

Any _blender command_ that takes no parameters and returns a value can be mapped to mode and then can be used in [condition] rule.

2.3. Example mapping

[conditions]     [key]        [name of command]
omod,3win,osel   f            toggle_face_display

means that object mode must be active, 3d window must be active, and an object must be selected. This is exactly what is written in [3]

2.4. Adding aliases

For faster invocation of _blender commands_ (including invocation of python script commands written by users), we can use an =alias= mapping rule:

alias            mov            grab_selection

This alias means, that everytime we write into command line =mov= and press =enter= the selection will be moved. In fact most users would prefer here =m= or =g=. Another example:

alias            space          enter
alias            mouse_button_2 enter

Now, those two seem a little confusing. For sure this is not the default blender behaviour. But this is the default behaviour for AutoCAD, and users of that program will be very happy to use those two aliases. It does following: if the command line is active you could write a _blender command_ then press space or right mouse button to invoke it (note that this is an =alias= rule, and =alias= rules only take effect when command line is active).

I hope this explanation is clear and you get the idea.

3. Overall benefits of Command Line

3.1. Old blender functionality kept

By introducing file =.Bkeymap= describing current blender behaviour the users will not notice any difference. They will work with blender the same way they did before. By pressing keyboard shortcuts.

3.2. Custom keyboard bindings

Users will be able to define custom keyboard mappings (like mapping =m= to =grab=)

3.3. Command Line

Now every command will have a name within blender. For example declare:

alias        sn                 popup_snap_menu

and the user types a command: sn, and voila, snap menu appears! :)

3.4. Easily mappable python scripts

All python scripts written for blender will have a name too. A name which will be treated equally the same way that _blender commands_ are treated. One writes a cool python script which introduces a command called do_this_funny_thing_to_the_texture, then maps this command:

true         ctrl-alt-shift-F12 do_this_funny_thing_to_the_texture
alias        dt                 do_this_funny_thing_to_the_texture

And voila - now this command feels and works like it was an internal command of blender!

3.5. Blender demos

Launch a blender with an input file that will be feed to command line. Now the user watches as blender does everything step by step.

3.6. Automated blender work

You could work on models without even invoking a GUI, just feed blender with _blender commands_ and enjoy the output! (like thumbnail of a .blend file, or a mandelbrot fractal drawn to the very detail)

4. Current Progress

To see the progress see MailArchive

-- DeveloperWikiJanekKozicki - 29 May 2004