OpenGL

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Todo: Write about custom OpenGL renderer in Xash3D/ Paranoia/ Cry of Fear and etc. (possibly also Counter-Strike Neo?)

OpenGL is a 3D graphics API, which is used by the hardware renderers of GoldSrc and id Tech 2, as well as some Source 2 games. It is also used on Source engine, for systems that doesn't support Direct3D ( macOS and Linux), as well as in Hammer 4.x.

Id Tech 2 Engine (GLQuake) OpenGL

id Tech 2 (GLQuake) uses OpenGL version 1.0.

Screenshot in-game of Quake GLQuake, using OpenGL.

Features

• Experimented Reflections
• Transparent Water
• Rudimentary Shadows

Note:To enables Rudimentary Shadows r_shadows must be set to 1

Note:Rudimentary Shadows in Half-Life were add in the 25th Anniversary update.

• Texture Filtering
• Water ripple
• 32-bit color
• Support for different resolutions

GoldSrc OpenGL

GoldSrc uses OpenGL version 1.0 which is same version as using the id Tech 2 (GLQuake).

Screenshot in-game of Half-Life, using OpenGL.

Features

• Colored lighting - Quake simply had monotone lighting
• Translucent and transparent textures - Glass can now be used in maps
• Water waves

Note:Water ripple from Quake replace by Water waves but not in Software Renderer the water ripple is used.

• Texture Filtering - Quake (GLQuake) simply Texture Filtering
• Detailed textures

Since 2013 SteamPipe Update

• FBO renderer - A new method of rendering the game, which allows MSAA to work with GoldSrc engine. This also allows the game to run on fullscreen in a borderless window.
• MSAA anti-aliasing - GoldSrc now natively performs 4x MSAA, reducing the amount of jagged edges/staircase effect on the geometry. This is automatically enabled when using the FBO renderer, unless the -nomsaa Command-line option is used.

Since 25th Anniversary

• Rudimentary Shadows

Note:To enables Rudimentary Shadows r_shadows must be set to 1

Source engine OpenGL

OpenGL uses ToGL to convert DirectX shaders to OpenGL for macOS and Linux and uses OpenGL version 2.1 which is similar to DirectX 9.0c. Additionally, Hammer uses OpenGL to render the 2D and 3D viewports.

Dxlevel 92

Dxlevel 92 is the OpenGL equivalent to DirectX 9 (Dx9)

Features

• Refractions with the use of a bump-map
• High-quality reflective water (used frequently)
• Softer edge dynamic shadows
• Normal-mapped lighting on models
• Improved-quality specular effects
• High dynamic range rendering (disabled by default)
• Phong shading
• Color Correction
• Motion Blur

Dxlevel 97

Dxlevel 97 is the OpenGL equivalent to DirectX 9 Shader Model 3 (Dx9.0c)

Features

• Lightwarp support
• High dynamic range rendering (enabled by default)

See also

• Direct3D
• Vulkan
• Software renderer

External links

•  OpenGL
•  GLQuake on Wikipedia
• GLQuake on Quake Fandom wiki