Source 2

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Source 2

Screenshot of Half-Life: Alyx, using the Source 2 Engine.

Developer(s)

Valve Corporation

Release date(s)

September 9, 2015

Platform(s)

Windows, macOS, Linux, Android, iOS

Written in

C++

SDK

Source 2 Documentation, game-specific Workshop Tools

License

Proprietary

Predecessor

Source

This article is about the game engine. For the documentation on Source 2 and its SDK, see Source 2 Documentation.

Todo: This page is not a stub but could use some more detail.

In-game screenshot of

de_dust2 in Counter-Strike 2. It is also the most recent and latest Source 2 game to be released.

Another in-game screenshot of Counter-Strike 2, with the community-made map "Lost Coast by CZXA1", showcasing the graphical capabilities of Source 2, such as Volumetric lighting, 8K textures and lightmaps.

Comparison of

de_nuke map in Source and Source 2.

Source 2 is a 3D video game engine developed by Valve as a successor to Source. Introduced in 2015, it is used in most Valve games since the release of Dota 2, including Half-Life: Alyx, Counter-Strike 2, Deadlock, and many more.

Development of Source 2 was planned after the release of Half-Life 2: Episode Two and other The Orange Box games. In 2010, Left 4 Dead 2 was privately ported to the Source 2 engine as a tech demo, with one of the maps recreated in the Source 2 engine. The engine was later made public with the Dota 2 Workshop Tools Alpha in August 6th 2014 and formally announced by Valve in March of 2015 at the Game Developers Conference. It was then implemented into Dota 2 on June 17th 2015, and finally publicly released in September 2015. Valve has announced that Source 2 will be released to the public for free, and it will only take money should it be used for commercial products. Despite this, unlike its predecessor, Source, the Source 2 engine was rarely licensed to any third-party game developers, aside from Facepunch Studios's S&box.

The engine is capable of rendering highly complex and well detailed scenes with minimal framerate drops, thanks to its new 64-bit support, new VIS method, alongside Vulkan, Direct3D 11, allowing for better multi-core rendering, better graphics and more efficient 3D rendering.

Features

Renderer

Support MSAA, FXAA and TAA anti-aliasing: Source 2 supports various anti-aliasing techniques, each with their own advantages & disadvantages. For more information, see anti-aliasing page.
Native DirectX 11® (Direct3D 11) and Vulkan® support, with Shader Model 5.0 and later.: Add various new rendering features that previous renderer used in Source (Direct3D 9 on Windows, and OpenGL on Mac/Linux) doesn't have. It also improve multi-threading support, which improves performance.; Vulkan, which succeed OpenGL, being a low-level API, additionally also reduces driver overhead and offer higher performance and more efficient CPU and GPU usage than both Direct3D 11 and OpenGL, and unlike Direct3D 11 and 12, Vulkan is cross-platform and open standard.
Support for both forward and deferred rendering pipelines.: Deferred rendering is a rendering technique that allow games to render as much lights with little performance impact. Deferred rendering are commonly used in most modern titles.; Games such as Counter-Strike 2 and Half-Life: Alyx uses forward renderer, while Deadlock and Dota 2 uses deferred renderer.
High-fidelity upscaling (in all games since as of 2021, ): NVIDIA DLSS (available in Deadlock) and AMD FSR is a upscaling algorithm available in Source 2 games since Dota 2 (2021 update) and Counter-Strike 2. When the user chose to run the game on lower resolutions to improve performance while using DLSS or FSR, both will attempt to upscale and sharpening the image to make it less blurry on native monitor resolution.; AMD FSR doesn't involve the use of machine learning, unlike DLSS and XeSS, and runs on traditional shading units. The first version, FSR 1.0 is a spatial upscaler based on or similar to the Lanczos algorithm, and is available in all Source 2 games since 2021 (Dota 2 update, Counter-Strike 2 and later Source 2 titles). FSR 2 and 3, which are both temporal-based and produces better quality than FSR 1.0, are available in Deadlock.; NVIDIA DLSS is a temporal-based method relying on Tensor Cores (which are only available in RTX 20 series card, and doesn't support AMD/Intel Arc graphics card). Deadlock is the only Source 2 game that uses DLSS (version 4.0).
Cascaded Shadow Maps: Real-time dynamic shadows from skybox.
Screen Space Ambient Occlusion support: Simulate soft shadows on area such as walls and other objects by examining an onscreen pixel, and then comparing its location in a depth buffer to the pixels around it.
Phong and Cook-Torrance^[confirm]^{[citation needed]} shading model
Physically Based Rendering support: PBR render graphics in a way that more accurately models the flow of light in the real world.
Volumetric lighting support.
Improved cubemap reflections: Source 2 cubemaps, by default, are in higher resolutions compared to Source. Cubemaps in Source 2 are also parallax corrected.
WebM: Source 2 uses WebM video, replacing the previous Bink Video format. This will allow in-game intro and cutscenes to take less storage space as WebM provides better compression compared to Bink. WebM is also a open-format compared to Bink video.
Volumetric smokes (only in ): Smokes are now volumetric objects, that can be interacted by grenades, bullets, and more. It also react to lighting and the smokes fill the spaces naturally.

Physics

Rubikon: Valve's new in-house physics engine, replaced Havok previously used in Source to reduce licensing costs. Includes support for Cloth Simulation.

Sound System

Steam Audio: Valve's new in-house sound system licensed under Apache 2.0 license, replaces proprietary Miles Audio System.
Improved Steam Audio: Sounds have been reworked to better reflect the physical environment, be more distinct, and express more game state. They have also been rebalanced for a more comfortable listening experience.
Other audio improvements: Improved audio and voice processing.^[Clarify]

Networking

Sub-tick system (in all games since ): Tick rate no longer matters for moving, shooting, or throwing.

UI

Panorama: Valve's new Custom GUI interface that resembles modern web design and authoring (HTML5/CSS/JS). Using .XML and JavaScript files, developers can create dynamic and clean HUDs and menus and even high-quality in-game interactable panels.; Scalable across any resolution, compared to VGUI used in previous Source games (prior to Left 4 Dead) which would become small if the game is running at higher resolution.

Tools

Integrated asset management via the Asset System.

New engine-integrated authoring tools, rebuilt from the ground up.

All compiling tools except VRAD are now merged into one. The map compiling tool are named as Resourcecompiler.

All Source 2 engine tools can be launched from

Asset Browser. It is similar to the now-deprecated Source SDK Launcher and Authoring Tools previously used in Source engine.

Hammer 5.x

WYSIWYG World editor

Completely rebuilt from the ground up, featuring modern polygon mesh editing tools.

ModelDoc Editor

Compile, view and edit models in one single tool.

Previous Source 2 games ships with Model Editor which serve the same purposes before being replaced with ModelDoc Editor.

Material Editor

Create, view and edit materials in one single tool.

Postprocessing Editor

Create and preview custom post-processing effects.

Source 2 Filmmaker

3D video editing tool, now updated for Source 2 engine with many improvements, such as:

Improved load times

Better integration with other engine tools

Dynamic & instant reloading of changed assets

Now rendering directly to MP4 movie files using the H.264 video encoding and AAC audio encoding

And much more...

Hardware accelerated ray-tracing for VRAD: Currently supports all NVIDIA RTX and AMD RX 6000 series (or later), and other RDNA2 GPU only. Intel Arc not supported yet.; VRAD3 now requires graphics card with ray-tracing support to preview & bake lighting. This will allow VRAD to quickly calculates lighting data.; VRAD3 is supported in all Source 2 games since 2022. Some games such as Half-Life: Alyx and SteamVR Home still provides previous version (VRAD2) for users who want to compile maps lighting on systems that does not support hardware accelerated ray-tracing.

Programming

64-bit support: Faster game performance, and allowing game to access over 4 GB of RAM. Previously, Source 2 also support 32-bit, which has been dropped with the release of Dota 2 update in 2021 (except SteamVR Home).

Other

Replaced brushes (BSP) with meshes (.vwnod_c): BSP and Brushes (from Source, which goes back to Quake and Quake II), has been replaced with meshes, and BSP is replaced with octree (.vwnod_c) for geometry partitioning. Brush entities has been also replaced with mesh entity.
Improved visibility optimization: Source 2's VIS has been rebuilt to work better with meshes. It works differently than Quake, GoldSrc and Source Visleaf system.; Maps on Source 2 are no longer required to be sealed off to calculate VIS, however failure to seal a map will cause noticeable errors in the VIS data, known as vis leaks.

Limitations

Warning:Support for 32-bit, OpenGL, DirectX 9 (includes Direct3D 9), XAudio, and macOS versions below 10.14 were removed in 2021 with the Dota 2 update. SteamVR Home is not affected. Newer games such as Half-Life: Alyx and Counter-Strike 2 don't support them.
Newer games like Counter-Strike 2 will also require a CPU with SSE 4.2 support.

Warning:Some games like

Counter-Strike 2 no longer support Squirrel, making things non-trivial to port and with no chance of a proper transition period when both implementations are functional.

Note:Unlike

Source, mod support for Source 2 games are limited to content-based mods only. There are no game code nor the Source 2 SDK Base.

Products using Source 2

Valve

Products made by Valve.

Released

Release date	Title	Platforms	Notes
9 Sep 2015	Dota 2	PC: Windows, Mac, Linux	A MOBA game. Sequel to 2003's Warcraft III mod, Defense of the Ancients (retroactively called as Dota 1, DotA for short). Originally using Source when launched in 2013, ported to Source 2 in Sep 9, 2015.
22 Feb 2016	SteamVR Performance Test	PC: Windows (VR)	Non-interactive version of the Robot Repair demo. No longer available for download.
5 Apr 2016	Robot Repair - a minigame from The Lab	PC: Windows (VR)	This is the only The Lab minigame that runs on Source 2, the rest runs on Unity.
9 Jun 2016	Destinations	PC: Windows, Linux (VR)	Photogrammetry and environment viewer. Deprecated and replaced by SteamVR Home.
19 May 2017	SteamVR Home	PC: Windows, Linux (VR)	Virtual Reality portal and social hub included as part of SteamVR.
28 Nov 2018	Artifact	PC: Windows, Mac, Linux	The Dota Card Game. The game was widely criticized by players who are disappointed with Valve abandoning the Half-Life series at the time, aswell as calling the game "pay-to-win", even prior to Artifact being released.
20 Jun 2019	Dota Underlords	PC: Windows, Mac, Linux Mobile: Android, iOS	Auto Battler game. This is currently the only Source 2 games to be released on mobile devices (both Android, iOS).
23 Mar 2020	Half-Life: Alyx	PC: Windows, Linux (VR)	First Half-Life game to be released since the release of Half-Life 2: Episode Two, which was released 12 years prior. Half-Life: Alyx was highly anticipated when it was announced.
2 Mar 2022	Aperture Desk Job	PC: Windows, Linux	A short playable demo set in Portal universe, used to demonstrate the Steam Deck. The game requires controller to play the demo.
27 Sep 2023	Counter-Strike 2	PC: Windows, Linux	Originally planned to be released in Summer 2023, it was delayed and later released in September 27, 2023. This is a port of Counter-Strike: Global Offensive to the Source 2 engine, under it's new name " Counter-Strike 2", which eventually replaced the original game. Most CS:GO maps were removed, while others have been remade from scratch.

Unreleased

This section are for unreleased games by Valve that are in development, not publicly released or is in Beta/Early Access.

Release date	Title	Developer(s)	Publisher(s)	Platforms	Notes
TBA	Deadlock	Valve	Valve	PC: Windows	Deadlock is a third-person shooter MOBA game currently in semi-private beta testing (invite only). The game features 21 characters you can play as. It is known internally as "Project 8" and formerly "Citadel". Players who already have access to Deadlock can invite another player(s) to have beta access.

Third-Party

Products made by third-party companies and mod teams.

Released

None yet.

In development/Unreleased

This section are for unreleased 3rd party games that are in development, not publicly released or is in Beta/Early Access.

Release date	Title	Developer(s)	Publisher(s)	Platforms	Notes
TBA	S&box	Facepunch Studios	Facepunch Studios	PC: Windows (VR optional)	As stated by Garry Newman himself, this is not intended to be a remaster of Garry's Mod, but rather, a spiritual successor. This is also the first time, and only time Source 2 was licensed to third-party developer. S&Box runs on heavily modified version of Source 2.

Source 2

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