Future version of the article "Source"

id Tech 2 ▶ GoldSrc ▶ Source ▶ Source 2

Summary | For developers

Source is a 3D game engine created by Valve in 2004, and is the successor to GoldSrc. Source has been used by Valve, third-party companies, and (much like GoldSrc) countless community mods by people around the globe.

Initial release date: 7 October 2004

Developer: Valve

Publisher: Valve

Platform: PC

Source is a 3D game engine created by Valve in 2004, and is the successor to GoldSrc. Source has been used by Valve, third-party companies, and (much like GoldSrc) countless community mods by people around the globe. Today, it has largely been replaced by the Source 2 engine for first-party usage since 2015, but it's still being commonly used today by modders and some third-party companies, and it's still regularly being maintained with engine and security updates.

Clarify: not all

Source games have

Valve Anti-Cheat. See

Apex Legends.

Clarify: The features list below may not applies to third-party or newer Source engine branches. For the list of branches, see this category page.

Renderer

Version 3.0 (and below) shaders

Note:Unofficially, some third-party games can also support Shader Model 5.0 and later by using Direct3D 11 and later, like Titanfall.

Anti-aliasing support
- Source is the first Valve engine to support anti-aliasing, prior to MSAA (4X) being added to GoldSrc in 2013.
- MSAA is the traditional anti-aliasing method, works by samples (renders) each pixel multiple times at different locations within the frame and averages the samples to produce the final pixel value. It is commonly used in most older video games, including almost all Source engine games (except Black Mesa (since the Xen update), Apex Legends, etc...). Up to 8x MSAA (or 6x MSAA in Source 2004) is supported. Older GPUs (such as pre-Maxwell Nvidia cards) also support CSAA.
- FXAA is also supported in CS:GO engine branch. Unlike MSAA, FXAA has less performance hit than most other AA methods due to it being a post-processing effect, which meant that it can be unofficially added to older Source engine games (or even other video games, other engines and other applications in general), using software such as ReShade, or even built-in via the graphics driver settings, and unlike MSAA, FXAA and other post-processing method will affect transparent textures, however, due to it's nature, this makes FXAA looks worse than many other AA methods as it's appear to blur the image, plus it does not reconstruct the pixel which was missing due to lack of an traditional anti-aliasing.
- TAA is a modern AA method commonly used in most modern games, superseded the MSAA method for anti-aliasing, it works by combining information from past frames and the current frame to remove jaggies in the current frame. However, as mentioned, TAA combines information from past and current frames can cause blurring and ghosting effect while in motion, more noticeable with low FPS. In Source engine case, it is only available in few games such as Apex Legends.
  Tip:If the game is running in 4K resolution or above, or by downscaling 4K to 1080p or lower, the need for anti-aliasing is greatly reduced.
Bump mapping and Normal mapping on models and the world
Author shaders with HLSL
Cube and environment mapping
- Cubemapping also supports Anisotropy (in all games since )
Phong shading for models
- Phong is also supported on world brushes (in all games since )
Dynamic lights, vertex lighting and lightmaps, many light types including flickering, pulsing etc.
HDR (in all games since ) and SDR/LDR (not in and later) lighting
Water with refraction, real-time world reflections and fresnel effects
- Water also supports flow mapping (in all games since )
Advanced particle systems that can emit sprites or models
Render-to-texture shadows allow for a large number of characters per scene
Occluder entities for visibility blocking
Indoor/Outdoor environments
- Deformable terrain
- 3D Skyboxes extend the horizon and add parallax on distant objects
- Dynamically rendered organics (grass, trees, etc.)
Subdivision surfaces, diffuse & specular bump maps
Real-time radiosity lighting
Real-time cascaded shadow mapping that comes from the skybox (in all games since )
Effects include but are not limited to: particles, beams, volumetric smoke, sparks, blood, & environmental effects like fog and rain
Scalability
- DX8-DX9 hardware supported (DX6-DX9 with modifications and fixed-function shaders)
- DX11 and later are also supported on some third-party branches.

Warning:DirectX 7 materials and earlier are no longer supported since Source 2007/Source 2009 (except

Portal with RTX). Games that uses

Left 4 Dead engine branch and later only support DirectX 9 materials.

Note:Source allows up to 8 LOD Models, although it does not have automatic level of detail out of box. Manual LoD is supported, however.

Warning:

Counter-Strike: Global Offensive currently does not support level of detail. $lod will be ignored, but the model will still work. Try to avoid using this command in

.

Materials System

Instead of traditional textures, Source defines sets of materials that specify what the object is made from and the texture used for that object. A material specifies how an object will fracture when broken, what it will sound like when broken or dragged across another surface, and what that object's mass and buoyancy are. This system is much more flexible than other texture-only systems
Materials can interact with objects or NPCs, such as mud or ice for vehicles to slide/lose traction on

Multiplayer Network Code

Time- and gamer-tested by millions of gamers around the world
Support for both LAN-based multiplayer and Internet-based multiplayer games
Prediction analysis for interpolating collision/hit detection
Optimizations for high-latency, high-packet-loss 56k connections

Advanced Characters

Detailed and believable characters
Realistic eyes
- Focus on player/object, not simply parallel views
- Proper eye bulge for realistic eye reflections
Simulated musculature provides outstanding emotions, speech, and body language
Language independent speech, characters can speak naturally in many languages
Skeletal/bone system for animation
Layered animation system can synthesize complex animations out of several pieces

Physics

Uses Havok physics engine, licensed from Havok Group (now acquired by Microsoft)
More responsive world with realistic interactions
Sounds & graphics follow from physics
AI characters can interact with physically simulated objects
Ropes/cables, machines, constraint systems, ragdoll physics
Can be controlled by level design
Kinematic animated bone followers
Custom procedural physics controllers
Vehicles
- Wheels slip and skid
- Realistic suspensions with springs on each wheel
- Realistic leaning during acceleration/deceleration and turning
- Individually tunable parameters such as horsepower, gearing, max speed, shift speed, tire material, tire friction, spring tension/dampening, etc.
- Multiple players in a vehicle in multiplayer
- Hovercraft support for cheaper simulation

Advanced AI

I/O system allows level designers to control AI
Sophisticated navigation: characters that run, fly, jump, crouch, climb stairs and ladders, and burrow underground
AI senses things using sight, sound, and smell
AI relationships determine friend/foe status of other entities
Battle AI allows squads of AI characters to operate together, know when to advance, retreat, lay cover fire, etc.

Sound System

7.1, 5.1 surround sound, 4 speaker surround

Bug:On system running Windows Vista and later, due to the game engine using DirectSound and older version of Miles Sound System, the game may output only 5.1 surround despite 7.1 selected or 7.1 audio may not work properly without custom dsound.dll (such as Creative Alchemy, DSOAL or IndirectSound). This issue is not affected by some third-party games, such as

Titanfall 2,

Apex Legends. [todo tested in?]

Note:Some Source games (such as

Alien Swarm,

Portal 2 and

Counter-Strike: Global Offensive) may not include options to enable 7.1 surround sound without using console commands.

High-quality 3D spatialization
Custom software DSP
Automatic DSP based on environmental geometry
Microsoft ADPCM-compressed WAV files
16-bit 44.1 KHz (CD Quality), stereo wave data with all features

Warning:48 KHz audio (DVD Quality) is not supported by default. Not to be confused with 44.1 KHz, which is the CD Quality audio.

MP3 decompression (requires Miles license)
Support for audio streaming on any wave ^[Clarify]
Real-time wave file stitching ^[Clarify]
Pre-authored Doppler effect encoded waves
Pre-authored distance variant encoded waves
Commentary system

UI

Server browser — Displays all active game servers and allows a player to choose which one to participate on. Players can filter and sort server lists in order to speed up the display and selection of a server.
VGUI — Valve's custom GUI interface mimics most of the Windows controls but is rendered using the Source engine for both in game and out of game uniform UI display. Some features:
- Dynamic in-game HUD display
- Many widgets/controls (e.g., buttons, treeview, html control…)
- Themes/custom visualization allowed
- Platform independent
- Localized text (Unicode compliant)
Panorama (in all games since ) — Introduced in 2018, 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 intractable panels.

Programming

All code written in C/C++ using Visual Studio .NET 2003 and later. Easily and quickly derive new entities from existing base classes
Internal context sensitive performance monitoring system
Graphics performance measurement tools built into the engine
Modular code design (via DLLs) allows swapping out of core components for easy upgrading or code replacement
VScript scripting system allows using external coding languages, such as Squirrel and Lua, in maps to create more complex systems (in all games since ) (also in )

Tools

HLFaceposer
- Facial expression tool used to craft speech and emotions
Valve Hammer Editor
- WYSIWYG World editor
- Create world brushes
- Terrain editor
- Place detailed world models and AI NPCs
- Set navigation points/paths for NPCs
- Place triggers, clip brushes, logic, etc.
- Allows level designer to hook up I/O between entities to control AI within the game
Half-Life Model Viewer
- Full model previewer
- Rotate models in any direction
- Set up hit boxes
- View physics hull
- View normals
- Wireframe, shaded or textured view modes
Studiomdl
- Model compiler
VBSP, VRAD, VVIS, VMPI
- Map compilation tools (bsp, lighting and visibility)
- VMPI — distributed compilation tool allowing level compiles to be spread across many PCs greatly reducing compile times
Exporters
- XSI, Max and Maya .smd exporters for exporting 3D models