(XXL)2015 Cube map transparency.

hey Rorn. I've never tried to use transparency in cubemaps, but I'm not sure if it actually works. Anyway, you have to choose one of the DDS types that support interpolated alpha channel, like DTX5. DTX1 may not support alpha channel, or when it does it only supports 1bit alpha channel (which means something is either fully opaque or fully transparent, like opacity maps in the game). Try DTX5 with interpolated alpha and see if it works. The downside of DTX 5 is that is compressed, so like a JPG losses a bit of quality when you save it (and more if you edit and re-save it several times). If DTX5 works, then you can experiment with other types of DDS that have no compression, but I'm not sure which one also supports interpolated alpha channel.

BTW if you are interested in making cubemaps, I've made a 3ds max scene to render them from panoramic images and a Photoshop template to create the cubemap from the images rendered in 3ds max, if you are interested in it, let me know.

EDIT: I'm not exactly sure if you want to blend a skybox with the default sky, or make the skybox completely transparent.

 

If you want 3ds Max 2012 send me a PM. You can get the latest versions for free from Autodesk's educational website. The thing is that with the latest versions of 3ds Max you'll have to use XXL's Artist tool, which means your models will be only compatible with XXL.

Back to the skyboxes.

Indeed. There are two types of skies in XXL: The default physical sky/Atmospheric display (same as XL) and the skyboxes.
The physical sky has the animated sun and the flickering stars. The skyboxes use textures so they aren't visible. Some of the sun's settings will only change its appearence while others change its physical proprierties.

There are three types of cubemaps. The skybox which is the high resolution one that is the sky texture, including sun, moon and starts. So they aren't animated.

The reflection cubemaps (street.dds I think it's the default) is the reflection you see on reflective surfaces, it doesn't affect the lighting but its colour is visible on the reflections) This cube map could be changed or desaturated to avoild that orange reflections, but keep in mind the reflections depend on it. Ideally, they should match the skybox's overal color, so you don't get orange reflections under a bright blue sky

Ambient cubemaps these cubemaps are the ones responsible for the ambient lighting color and its intensity. They illuminate the scene globally and provide light where the sun doesn't. Trees can use a different ambient map.

So for your project could choose if you want to create a new skybox (which will be independent and selectable from the dropdown menu) and only compatible with XXL, or change the settings for the atmopheric display, the old sky which will replace the default atmospheric display, but it will be compatible with XL too.

Either way, you basically want the level to be completely lighted by white light.

Change the sun color to white, (or different shades of grey, it will lower its intensity).

Use a desaturated/grey to white gradient or solid desaturated color cubemap as ambient (general and trees)


Keep in mind that pure white lighting will not look realistic at any time other than noon. (even at noon sunlight is not 100% white, though is quite close being slightly on the warm side).

 

The physical sky, which is called Atmospheric Display in the game is based on physical propierties like light scattering, rayleigh, etc. It doesn't use any texture. This is the default sky in XL and it's still available from the drop down menu in XXL. The sun/moon transitioning across the sky and starts flickering will be only available with this type of sky.

The name of the folder data/engine/skybox is misleading. Since it doesn't contain skybox textures, but cubemaps used for ambient light and reflections.

The skyboxes they added in XXL are based on a textured dome. Cubemaps to texture this dome should have the sun positioned on the right side North-South and East-West. Since the sun is still on the image you can never match its actual position, but at least should be on the same side as the lightsource.

Reflection and ambient cubemaps work the same in both types of skies.

The actual textures used by skyboxes (textured dome) are located in data\gfx\sky\cubemaps. They don't affect the lighting in the scene in any way, they are used just as a background.

Reflection maps, ambient maps, skybox textures and the physical sky are completely independent one of the other. But each one is limited to a specific task.

The skybox textures are just a backdrop. They do nothing other than that.

The reflection maps only affect the reflections on objects/buildings and water.

The ambient cubemaps contribute to the general lighting of the level.


So if you want to make a selectable skybox, you can either use some of the cubemaps in data\gfx\sky\cubemaps to associate to your own env.xml file, or you can change the settings of the defaultevironment file, which controls the physical sky. I'm not sure if you can make a custom env.xlm that doesn't use a skybox but the physical sky instead. I've never tried.

This is an example from my blue hour skybox mod:

Skybox texture (actual size 1024x1024 each side)


Reflection Map (actual size 512x512 each side) Note the position is different.


Ambient map (actual size 128x128 each side) This one gets several blur passes, so its details don't matter.


To achieve white lighting you would only have to desaturate the ambient cubemap and keep your sun settings as you show above. If you desaturate the reflection cubemap you'll get grey reflections. The skybox texture will not make any difference.

 

I'm glad to help

The only limitation in the student version is that you're not allowed to use it for commercial purposes. The software works exaclty as the paid version, it will pop up a message about the files created with a student version whenever the file is opened in another installation of 3ds max, but other than that, it's it's the same.