• Features

This page is quite technical. You can see groups of the engine, game and tools derived by the id Tech 3 GPL source.

Engine

• derived from the IOQuake3 engine

General

• console provides a backbone for game management, and allows in-game console variables and commands

Renderer

General

• access to the OpenGL driver through a new interface designed like OpenGL ES 2.0 with additional support for OpenGL 3.0

  • removed OpenGL calls that are marked as deprecated in the OpenGL 3.0 specification
  • all rendering is handled by GLSL shaders
  • avoids bottlenecks in the OpenGL driver by avoiding state changes

• makes usage of the latest OpenGL extensions

• hidden surface removal algorithm using the Q3A BSP and PVS
• arbitrary resolution support (including widescreen)

  • clever usage of vertex buffer objects (VBO) to speed up rendering of everything

    • avoids geometry processing at render time using the CPU (worst bottleneck with the Q3A engine)
    • memory efficient implementation with static VBOs for BSP models and static/dynamic IBOs for BSP clusters
    • static game models like powerups use static VBOs as well
    • renders up to 500 000 - 700 000 polygons at 50-60 fps on current hardware

• anisotropic texture filtering

• optional uniform lighting and shadowing model like in Doom 3

• usage of frame buffer objects (FBO) to perform offscreen rendering effects

• reactivated and extended TrueType font support using FreeType

• optional deferred shading with r_deferredShading 1

Supported Image Formats

• Truevision Targa (.tga)
• JPEG File Interchange Format (.jpg)

• Portable Network Graphics (.png)

• DirectX .dds image file format support

Supported Model Formats

• Quake 3 .bsp
• Quake 3 .md3

• Doom 3 .md5mesh

• Doom 3 .md5anim

Lighting

• dynamic and static realtime lights that can use Doom 3 style boxed lighting attenuation also known as globe mapping

  • lights can have .mtr shaders like surface materials

    • 1 lightFallOff image for Z attenuation

    • up to 15 shader stages for XY attenuation

    • RoQ videos can be used for light attenuation

  • omni-directional lighting (point lights)

  • projective lighting (spot lights)

  • hardware occlusion culling removes light volumes behind opaque geometry

• precomputed lighting
  • lightgrid lighting for entities
  • simple light mapping for world geometry

  • directional 'deluxe' light mapping for world geometry

  • can be used with Doom 3 materials without the need to change them

Shadowing

• [cg/r]_shadows
  • 1 = blob
  • 2 = planar projection

  • 3 = stencil shadow volumes (Doom 3 style)

  • 4 = variance shadow mapping (16 bit float precision)

  • 5 = variance shadow mapping (32 bit float precision)

  • 6 = exponential shadow mapping (32 bit float precision)

• soft shadows (only available for shadow mapping techniques)

• dynamic LOD for shadow mapping

• many new cvars to make shadow mapping very scaleable on future GPU hardware

Materials and Shaders

• simple scriptable material shader language support

  • supports almost all Doom 3 .mtr keywords

  • XreaL specific extensions to make development easier

  • translucence
  • two-sided polygons
  • arbitrary polygon offset
  • dynamic transformations of UV coordinates
  • alpha testing
  • glow textures
  • normal mapping
  • specular maps
  • different blending functions
  • texture compression parameters
  • dynamic color generation
  • game entity associated behavior

  • different textures can be combined to new ones at load time

Special effects

• heat haze post process effect

  • you can render many different distorsion effects with this:
    • heat shimmer
    • water
    • glass

• light bloom post process effects

  • r_bloom cvar determines bloom mode
  • 0 = no bloom
  • 1 = simple bloom with diamond filter only
  • 2 = strong bloom with combined gauss and diamond filters

• rotoscope cell shading post process effect (just for fun)

• global fog post process effects

• depth of field post process effect

Skeletal Animation

• new interface exposed from the renderer to handle model and animation files

• renderer interface abstracts file formats like (.md5mesh/.md5anim)

• animations can be handled seperately

• animation frame interpolation

• animation blending

• up to 120 bones for each refEntity_t that can be modified outside the renderer

• basic support for inverse kinematics like head/torso/legs player angles

• bones can be used as joints to attach other refEntities

• CPU vertex skinning

• ultra fast GPU vertex skinning on DX10 hardware where 32 visible high polycount characters are no problem

Networking

• Multiplayer over LAN and Internet via a Client and Server architecture
• Up to 64 players
• low-bandwidth efficient
• packet fragmentation
• packet compression and encryption

• IPv6 support with multicasting abilities

• extended protocol to support accelerating trajectories

Client

• .avi video and audio recording

• libcURL http-download redirection support for fast downloads of referenced server .pk3 files

Server

TODO add information

Physics

• Continues Collision Detection
  • AABB tracing against brushes, bezier curves and other primitives
  • Sphere tracing
  • Capsule tracing

• optional per triangle collision detection for world surfaces

• improved collision detection speed using early-out AABB tests

AI

• replaced Gladiator bot by the Quake2 ACEBot

  • very basic and extensible AI code
  • uses waypoints that are set automatically by running through a map
  • does not require to build AAS files
  • can even work with maps that don't feature collision brushes

Sound

• streamed sounds
• entirely loadable sounds
• 3D sound
• Doppler effect
• Different sound API support:
  • Software backend

  • OpenAL backend

Supported Audio Formats

• RIFF WAVE (.wav)

• OGG Vorbis audio file format support (.ogg)

Platforms

The XreaL engine is platform independent. Which means in this case it will run on more than one platform, which are currently:

• Windows 2000, XP, XP64, Vista
• Linux

• Mac OS X (Universal, PPC & x86)

Game

Client Game

• Tenebrae style player teleporter effect

• rotating gibs

• Unlagged Code

• improved status bar

• improved particle engine

• experimental Lua 5.1 layer for particle creation and other special effects

• robust skeletal player animation code

• robust skeletal view weapon animation code

Server Game

• matrix math

• quaternion math

• improved tokenizer

• handy string utilities like Q_strreplace

• experimental Lua 5.1 layer for level entity scripting allowing map designers to control entities like in Doom3

• Unlagged Code

• accelerating rockets

• true quad damage

User Interface

• bloom rendering game option

• anisotropic filter value slider in the graphics options

• lighting and shadowing options

• scrolling credits

XMap2

• derived from the popular Q3Map2 compiler by Randy ydnar Reddig

• Doom 3 .map file support Version 2

• Quake 4 .map file support Version 3

• support for new entity epairs like the "rotation" matrix

• Doom 3 .mtr shader support

• can be run by GtkRadiant and communicates with it using a XML based network protocol

• can be run by several Q3Map2 frontends like Q3Map2Tools or Q3MapGUI

• supports -game xreal option for best usage with XreaL

GtkRadiant

• lite version based on Zerowing code
• modified for XreaL mapping
• realtime lighting preview with F3