To get it up and running for both OpenArena & GtkRadiant is fairly simple.
You need 2 files, a textures & a shader script.
Create yourself a texture:
Name: test.tga
Dimensions: 256x256 (All textures in OpenArena must be of ^2, for example 512x512, 256x128 etc)
Location: .openarena/textures/test/test.tga
Create a shader:
Name: test.shader
Text:
textures/test/test
{
{
map textures/test/test.tga
rgbGen identity
}
{
map $lightmap
blendfunc filter
}
}
Location: .openarena/scripts/test.shader
Load GtkRadiant and check the texture list you will find a new row named 'test' with your desired texture.
Create a quick map with this texture & compile. Name the map test2.map
Create a .zip archive, name it test.pk3
With in test.pk3 place the files above so it should look something like:
textures/test/test.tga
scripts/test.shader
maps/test2.bsp
Open OpenArena & bring down the console type: /devmap test2
The map will run & you should see your textures. You cant have weird dimensions for textures e.g. 153x153
Best to keep to these dimensions: 16, 32, 64, 128, 256, 512, 1024.
Hope this helps you.