Add page on Alpha Transparency

markdown/landing/index.md

@@ -32,7 +32,7 @@ At this current moment, no marked-stable builds of Nazi Zombies: Portable are ma
 
 ## Core Documentation
 
-Core documents contain information about Nazi Zombies: Portable's internal design. They are not specifically relevant to custom content creators, though overlap will be present for map features that interact with NZ:P's QuakeC.
+Core documents contain information about Nazi Zombies: Portable's internal design. They may not be specifically relevant to custom content creators, though overlap will be present for map features that interact with NZ:P's QuakeC or for specialty features.
 
 - [Dedicated Server](../internal/dedicated-server.md)
 - [Weapon IDs](../internal/weapon-ids.md)
@@ -47,6 +47,7 @@ Documentation and by extension headers/categories are a work in progress.
 - [External References](../mapping/external-references.md)
 - [Customizing Mystery Box Weapons](../mapping/mbox2-format.md)
 - [Advanced Model Exporting](../mapping/model-exporting.md)
+- [Model Alpha Transparency](../mapping/alpha-transparency.md)
 
 ### Map Entities
 - [Barricades](../mapping/barricades.md)

markdown/mapping/alpha-transparency.md

@@ -0,0 +1,20 @@
+% Model Alpha Transparency - NZ:P Mapping Documentation
+# Model Alpha Transparency
+
+## Introduction
+
+![The Mystery Box Glow is a model using Alpha Transparency](../res/images/mystery_glow.webp)
+
+_Nazi Zombies: Portable_ has it's own unique method of enabling alpha blending for models, equivalent to the `GL_SRC_ALPHA GL_ONE_MINUS_SRC_ALPHA` OpenGL blend mode. This process is supported by all platforms and the set up is identical for all of them.
+
+## Texture Format
+
+![The Mystery Box Glow texture in GIMP](../res/images/mystery_glow_gimp.webp)
+
+`.TGA` formated textures are the only ones supported for this method, and they can safely be exported as 32 bit RGBA.
+
+## Naming Convention
+
+![The Mystery Box Glow file name](../res/images/alpha_texture_spec.webp)
+
+The texture follows the same naming convention as standard Quake external textures. That being `model/path/your_model.mdl_<skin_index>.tga`. However, the model name itself has a unique identifier. The last character of the name (*before* the file extension) must be `$`. What this does internally is redirect the model renderer to a different pipeline that sets the given blend modes on non-FTE, and creates a Quake III shader inside of FTE in the `scripts/` path on first launch.