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 cross-platform 3D graphics API, which is used by the hardware renderers of GoldSrc and id Tech 2, as well as one Source 2 game (Dota 2). It is also used on Source engine, for systems that doesn't support Direct3D (macOS and Linux), and for GLView.

OpenGL was later superseded by Vulkan, released in 2016. OpenGL was discontinued in 2017, having reached version 4.6.

id Tech 2 (GLQuake)

Todo:  Quake II has additional stuff that goldsrc uses

id Tech 2 (GLQuake) uses OpenGL version 1.0.

Screenshot in-game of Quake GLQuake, using OpenGL.

Features

• Experimental Reflections
• Translucent Water
• Dynamic Shadows

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

• Texture Filtering
• 32-bit color

GoldSrc

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

Confirm:According to PCGW, it mentions that HL uses OpenGL 2.1 (with latest version). Confirm if Mac or Linux version use any other version of OpenGL such as 2.1 or 1.x like Windows.

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
• Texture Filtering - like GLQuake
• Detail textures (since 2004)
• Dynamic Shadows (r_shadows; removed in 2003 Steam update, but re-added in 25th Anniversary update)

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.

Svengine

Svengine uses OpenGL 1.x with some 3.x features.

Source

In Source, OpenGL uses ToGL to convert DirectX shaders to OpenGL for macOS and Linux and uses OpenGL version 2.1 which is similar to Direct3D 9.0b.

Dxlevel 92

Dxlevel 92 is Source's OpenGL equivalent to DirectX 9 Shader Model 2 (DX9.0b)

Features

• Lightwarp support
• High dynamic range rendering (enabled by default)
• 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
• Phong shading
• Color Correction
• Motion Blur

Source 2

Dota 2 is the only Source 2 game which supports OpenGL. It uses OpenGL version 2.1.

OpenGL support for Dota 2 was dropped with the November 15th, 2021 update for Windows, and later Mac/Linux, with the optional OpenGL DLC for Windows completely emptied.

See also

• Direct3D
• Vulkan
• Software renderer

External links

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