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45 lines
No EOL
2 KiB
Markdown
45 lines
No EOL
2 KiB
Markdown
% Fog - NZ:P Mapping Documentation
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# Fog
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## Introduction
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_Nazi Zombies: Portable_ uses it's own 5-parameter, linear fog system. This was originally conceived this way as the PlayStation Portable's hardware fog is *linear* and not *exponential* as is traditional for Quake and OpenGL itself. The Nintendo 3DS also adheres to this standard thanks to [picaGL](https://github.com/masterfeizz/picaGL/tree/revamp)'s linear LUT fog. Other platforms manipulate these fog values to approximate them into standard `exp2` fog modes. Exponential fog is significantly less granular and as a result this approximation will never be spot-on.
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## Parameters
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```
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usage:
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fog (start) (end) (red) (green) (blue)
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```
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*Excerpt from `fog` command in the console.*
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When defining fog, you can provide a `start` and `end` distance, in units, of the fog "wall" that appears. The distance between `start` and `end` will impact intensity, and of course, the farther away `start` is from zero, the more visibility you have before the fog begins.
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You can change the color of the fog given individual `red`, `green`, and `blue` color values. These values range from `0`-`100`, with `100` being maximum intensity. Both pure black fog with `0 0 0` and pure white fog with `100 100 100` are supported.
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As an example, below is the fog output for *Nacht der Untoten*:
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```
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current values:
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"start" is "240"
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"end" is "1550"
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"red" is "54"
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"green" is "55"
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"blue" is "59"
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```
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## Translation
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### Linear to Exponential
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Platforms that do not support linear fog will algorithmically approximate a decent exponential fog density to use instead. The formula is as follows:
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```
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fog_density_gl = ((fog_start / fog_end)/3.5f)
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```
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### Exponential to Linear
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FTE will still fallback to old `exp2` fog behaviors if provided them, however all other platforms will ignore fog if any of it's provided values are less than zero. This is intended behavior. |