Source features fast, reliable and flexible technology to render computationally intensive game environments. The highest-performing shader-based rendering available to game developers helps you quickly produce even the most complex scenes quickly and efficiently. Source’s renderer utilizes advanced processor technologies such as multi-core and SIMD, as well as the latest GPU features via DirectX, to bring your vision to life in vibrant detail.

Advanced Shader Technology

Support for HLSL shaders. Author shaders for the Direct3D pipeline using up to shader model 3.0.

Advanced Shader Library. Use Valve’s existing shader library or augment with your own algorithms. Existing techniques include all manner of sophisticated lighting effects from the non-photorealistic rendering (NPR) style of Team Fortress 2 to the hyper-realistic look of the Half-Life 2 episodes—all in one engine.

LOD on Models and World. Achieve maximum performance on all levels of hardware with automatic management of geometric Level of Detail (LOD).

Alpha-to-Coverage. Enables antialiasing of alpha-tested primitives such as foliage, fences, and grillwork.

Infinite Resolution Masking. Use distance-coded alpha masking for infinite resolution texture masking—useful for resolution-independent UI elements or any alpha-tested primitives.

(1) Features like water refraction and High Dynamic Range lighting enhance visual fidelity and believability in Source-powered games. (2) Create and edit particle systems in the Particle Editor.

Dynamic Lighting and Shadows

Radiosity Lighting. World geometry is lit with radiosity lighting stored in light maps or per vertex to provide immersive environments. Light maps encode directional information so that lighting combines naturally with bump maps, resulting in more accurate lighting of local surface detail, including self-shadowing. Radiosity is computed using a distributed radiosity solver (vrad) which can be deployed across your local network for rapid iteration on world lighting.

High Dynamic Range (HDR) Lighting. All lighting data including light maps, environment maps and dynamic lights in the scene are computed in high dynamic range space for natural lighting. High dynamic range lighting is supported in the Source engine on all DirectX 9 level hardware, unlike most competing engines.

Radiance Transfer/Indirect Lighting. Dynamic objects and characters in the world pick up bounced light computed during offline radiosity computation. This lighting effect truly grounds characters and other dynamic objects in the game world.

High Performance Dynamic Shadows. Dynamic objects and characters in the world generate high performance shadows which are projected onto world geometry, providing critical lighting cues.

Shadow Depth Mapping. Shadow depth textures allow for realistic self-shadowing of objects in the world, providing a more realistic and immersive effect, at a greater cost than RTT shadows.

Rim Lighting. A separate rim lighting term can be used to highlight key characters, as in Left 4 Dead, or provide a stylized look, as in Team Fortress 2.

Advanced Material Rendering. Apply diffuse, specular, detail, emissive, iridescent and other special effects.


Full Range of Special Effects. Including particles, beams, volumetric smoke, sparks, blood and environmental effects like fog and rain.

Particle Effects. Source’s advanced particle system can emit sprites or models for realistic fire, explosions, snow, and more. Multicore graphics optimizations improves particle rendering performance.

Particle Editor. Edit and create particle systems with fully interactive preview and the ability to see edited systems immediately in the game.

Soft Particles. Particle shaders use scene depth information to eliminate hard intersections seen in traditional particle rendering.

Motion Blur. Render full-screen camera motion blur in real-time.

Water. Generate realistic-looking reflective water surfaces with refraction and Fresnel effects.


Material System. 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 struck or dragged across another surface, and what that object’s mass and buoyancy are. This system is much more flexible than other texture-only based systems.

Self-shadowed Bump Maps create soft shadows and ambient occlusion with both dynamic and pre-calculated radiosity lighting. Source renders self-shadowed bump maps on both current and older-generation graphics hardware.

Wrinkle Maps. Particularly useful for facial and clothing wrinkles, additional texture maps are blended in to provide dynamic surface detail in areas of models which compress and stretch.

Detail Textures. Combine low frequency textures with high frequency detail to conserve video memory while maintaining apparent texture density.

Versatile Multi-Texture Blending. Define blend masks with variable sharp edges, combine textures using multiple different modes, and apply per-surface color correction.

Dynamic Color Correction. Interactively edit the color cast and contrast of your scene to match the desired art style.

(1) Examples of non-photorealistic rendering, advanced facial animation, shadow depth mapping, Phong shading, (2) advanced material rendering, self-shadowing bumpmaps, particle effects, and rim lighting.