TASing

TASsing

This wiki page intends to introduce beginners to Portal 2 TASsing by explaining how to play one in-game and how to write one. It also serves as documentation for the TAS tools.

Introduction

Setup

• Install  SAR if you do not have it already.
• Create a new folder called tas in your Portal 2 directory. This is where all your tas scripts will live.

The script files will need to have a .p2tas extension and can be played using the command sar_tas_play <filename>. So for example if your script file is Portal 2/tas/mytas.p2tas, then to play it in-game you would use the command sar_tas_play mytas.

The .p2tas file format

.p2tas is somewhat similar to .srctas.

Start commands

At the beginning of a file, you have to include a start command. It can have five parameters: now, save, map, cm or next.

• start now: Starts playing the TAS immediately, or as soon as a session is started.
• start save <save_name>: Starts playing the TAS after loading the given save.
• start map <map_name>: Starts playing the TAS after loading into the given map.
• start cm <map_name>: Starts playing the TAS after loading into the given map, but in Challenge Mode.
• start next: Starts playing the TAS on the next session start.

Examples:

start save quick
start map sp_a1_intro3

Comments

Comments are sections that will be ignored and can be expressed in 2 ways:

• Single line comment with //
• Multiline comment by opening with /* and closing with */

They are useful for adding notes in your script or to temporarily prevent a line from being executed.

Every other line that isn’t start, a repeat block (explained later) or a comment is considered to be a framebulk.

The framebulk

Framebulks store the inputs and commands that should be executed by a virtual controller at a given tick. They’re formatted like this:

tick>movement|angles|buttons|commands|tools

Below is an explanation of each field in a framebulk:

Tick

The number of ticks since the beginning of the TAS. This dictates when the framebulk will be executed. It can also be written with a + in front, in which case it will indicate the number of ticks compared to the previous framebulk instead.

Examples:

• If a tick value is 20, the framebulk will be executed 20 ticks after TAS script has started.
• If a tick value is +10, the framebulk will be executed 10 ticks after the previous framebulk.

Movement

Two floating point values from -1.0 and 1.0 representing horizontal and vertical movement analog values respectively.

Example: 0 1 as movement field will move the player forward.

Angles

Two floating point values representing horizontal and vertical view analog values respectively. The values correspond to view rotation in degrees in one tick.

Example: 5 0 as analog field will turn the player 5 degrees to the right in the given tick.

Buttons

A list of digital inputs that should be pressed or released. Each digital action has a letter assigned. These actions are Jump, Duck, Use, Zoom, Blue portal and Orange portal. Uppercase letter presses down the input, lowercase letter releases it.

Additionally, by putting a number after an uppercase button, you can specify a number of ticks after which it will be released automatically.

Example: dU1J as buttons field will release duck button, press the use key for 1 tick and press jump input. All other inputs will remain at their previous state.

Commands

A string representing a console command or a set of console commands separated by semicolons. Everything typed here will be executed in the console.

Example: say I hate this game;quit will print "I hate this game" in game’s chat and turn the game off.

Tools

A string representing an automation tool command or a set of tool commands separated by semicolons. The usage of automation tools will be explained later.

Everything connected together gives us an example of a complete framebulk:

20>0 1|5 0|dU1J|say I hate this game;quit|strafe max

Preserving rules

TAS script player will keep the previously set state of a virtual controller input if no information about it was given for current tick. This allows you to skip certain parts of a framebulk or even entire framebulks if you want specific input to continue for a specific amount of ticks.

Examples below are just random framebulks. Dots at the top and the bottom are there to show that it’s only a part of a full script, and you should think about these examples as such.

Example 1: There are no framebulks for ticks 11 to 19, the player will just continue going forward until the tick 20.

...
10>0 1|0 0|jduzbo||
20>0 0|0 0|jduzbo||
...

Example 2: Framebulk 15 is missing information about button states. Jump will be held for that tick.

...
14>0 0|0 0|Jduzbo||
15>0 0|0 0|||
...

Example 3: Framebulk 21 has only movement field and 22 has only button field with lowercase d. Player will move for 11 ticks while trying to crouch, stop moving at tick 21 and stop crouching at tick 22.

...
10>0 1||D
21>0 0
22>||d
...

Notice that, even though fields are not mandatory, you have to use the separator | characters to reach the correct field. Button field is the third one, so even if you don’t use movement and analog fields, you have to put two separators before it.

Additionally, commands and tools fields are not preserved. In other words, they won't be repeatedly executed every tick until the field is “cleaned up”. They will execute only once in a tick specified by a framebulk.

Automation tools

Automation tools are controlled through the tools field, which works in a similar way to the commands field.

Tools work by modifying the view/movement analog and button fields in the framebulk every tick. The order in which the tools are evaluated is defined by the order they appear in the framebulk. For instance, if the tools field is setang 10 20;strafe max, the setang tool will be run before the strafe tool, which means the autostrafer is able to "predict" the angle change caused by the setang (which is important since angle changing is the first thing to happen in a tick). In general, angle-changing tools (setang, autoaim) should be placed before movement tools (strafe, absmov, decel) for the tools to work accurately.

Here are the tools that are currently implemented:

Strafe tool

The strafe tool will adjust player input to get a different kind of strafing depending on parameters.

Syntax: strafe [parameters]

Possible parameters:

Strafing type control:

• none or off - disables strafing entirely.
• vec - enables vectorial strafing (movement analog is adjusted to get desired movement direction). (default)
• ang - enables angular strafing (view analog is adjusted to get desired movement direction). This isn't particularly recommended as it doesn't look appealing, however it is the only effective strafing type while on velocity gel.
• veccam - enables special vectorial strafing that rotates you towards your current moving direction.

Velocity control:

• max - makes autostrafer aim for the greatest acceleration. (default)
• keep - makes autostrafer maintain the current velocity.
• [number]ups - sets a target velocity of [number] units per second for the autostrafer

Strafe direction control:

• forward - autostrafer will try to strafe in a straight line, towards the current view angle. (default)
• forwardvel - autostrafer will try to strafe in a straight line, towards the current velocity angle.
• left - autostrafer will try to strafe left
• right - autostrafer will try to strafe right
• [number]deg - sets a target yaw angle of [number] degrees autostrafer should strafe towards.

Other:

• nopitchlock - Make the autostrafer not clamp the pitch. The autostrafer will always clamp your pitch angle (up and down) between -30 and 30 when midair, as it gives the fastest possible acceleration (forward movement is being scaled by a cosine of that angle while being airborne). This argument will tell the autostrafer that you wish to enable sub-optimal strafing (this is useful when you need to hit a shot while strafing for example).

Examples:

• strafe 299.999ups left veccam - strafes left while facing current view angle and trying to reach the velocity of 299.999ups (the highest velocity you can get without being affected by the limited air control).
• strafe vec max forward - strafes with maximum acceleration on a straight line without changing view angles.

Autojump tool

Autojump tool will change the jump button state depending on whether the player is grounded or not, resulting in automatically jumping on the earliest contact with a ground.

Syntax: autojump [on]

Anything other than on will disable the autojump.

Examples:

• autojump on - enables autojump.
• autojump off - disables autojump.

Absolute movement tool

Absolute movement tool will generate movement values depending on the absolute move direction you provide in degrees.

Syntax: absmov <angle> [strength]

Giving off as an argument will disable the tool. The strength parameter must be between 0 and 1 (default) and controls how fast the player will move.

Examples:

• absmov 90 - enables absolute movement towards positive Y.
• absmov 90 0.5 - enables absolute movement towards positive Y, but half as fast.
• absmov off - disables absolute movement.

Set view angles tool

This tool works basically the same as setang console command. It will adjust the view analog in a way so the camera is looking towards given angles.

Syntax: setang <pitch> <yaw> [time]

The tool will set the pitch and yaw according to given angles in degrees. time specifies how long a transition to new angles takes, in ticks. If omitted, transition happens instantly.

Examples:

• setang 69 42.0 - instantly rotates the camera to angles 69 42.
• setang 0 0 20 - slowly rotates the camera towards angles 0 0 over the next 20 ticks.

Auto aim tool

The Auto Aim tool will automatically aim towards a specified point in 3D space.

Syntax: autoaim <x> <y> <z> [time]

Giving off as an argument will disable the tool. Time specifies how long a transition to aiming at the point takes, in ticks. If omitted, transition happens instantly. When using this command to place portals, the command portal_report can be helpful. In other cases, the command sar_aim_point_hud 1 is recommended.

Examples:

• autoaim 0 0 0 - aims at world origin.
• autoaim 0 0 0 20 - aims at world origin, but smoothed over 20 ticks.
• autoaim 1000 2134 47381 - aims fucking nowhere.

Deceleration tool

The deceleration tool will slow down as quickly as possible to the given speed.

Syntax: decel <speed>

Giving off as an argument will disable the tool.

Examples:

• decel 100 - decelerates until it reaches 100ups and then turns off.
• decel off - turns off the decel tool.

Loops

By putting a part of your script in a repeat block, you can repeat it X amount of times.

Example: This block will spam the use key ten times. The indentation is not required.

repeat 10
    +1>||U
    +1>||u
end

These blocks can be nested. Also, keep in mind that both repeat and end keywords are case-sensitive (they have to be lower-case to work).

In-game commands

You can see a list of the TAS commands by playing find sar_tas in the in-game console, however here is a list of the main ones:

• sar_tas_play <filename> [filename2] - plays the given TAS script. If two filenames are given, play as a coop TAS. The first script is blue and the second is for orange.
• sar_tas_stop - Stop the currently playing TAS.
• sar_tas_replay - Replay the last played TAS.
• sar_tas_pause - Pause the TAS playback.
• sar_tas_advance - Advances TAS playback by 2 ticks in singleplayer and 1 tick in coop.
• sar_tas_resume - Resume TAS playback.
• sar_tas_skipto <tick> - Fast forwards the TAS up to the given tick. 0 disables fast-forward.
• sar_tas_pauseat <tick> - Automatically pause the TAS at the given tick. 0 disables pausing.

Other useful things

The TASsing experience can be aided by a small number of other tools such as:

Visual Studio Code Extension

There is an extension for Visual Studio Code that adds syntax highlighting to TAS scripts, as well as a few of useful features like integration with SAR that allows playing back the TAS from the extension. (this requires enabling sar_tas_server 1 in-game).

You can install the extension by opening the extensions sidebar and searching for "p2tas".

Player Trace

By running sar_trace_draw 1 as well as placing sar_trace_record 1 at the beginning of the TAS script and sar_trace_record 0 at the end in the commands field, a line tracing the path of the player will be drawn in-game.