ATTR_cockpit_region – Are We Confused Yet?

The choice of panels (2-d panel vs. 3-d panel) for your cockpit and the choice of OBJ commands (ATTR_cockpit vs. ATTR_cockpit_region) both affect how your 3-d cockpit looks.  Since these two techniques can both be varied, there are a lot of combinations, and 920RC2 does not have the right behavior.  (RC3 will fix this I think.)

The 3-d panel is a new flat panel whose purpose is to provide the image for ATTR_cockpit or ATTR_cockpit region.  Building a new panel for 3-d has a few advantages:

• The instruments can be packed together – no need for windows or other texture-wasting elements.  This can help reduce panel size — panel size is expensive when using ATTR_cockpit_texture.
• The 3-d panel can be smaller than the 2-d panel; having a huge panel feed the 3-d object is slow.
• Instruments that are drawn with perspective in the 2-d panel can be redrawn orthographically, which is more useful for texturing real 3-d overhead panels.

Because the 3-d panel is meant only to be used as part of a 3-d cockpit object, spot lights and flood lights are not available, nor is a night-lit alternative.  Why not?

• Such customized 2-d lighting would not match the rest of the 3-d cockpit visually.
• We will eventually have a more global lighting solution.

Basically I don’t want to provide features that will clash with the future implementation and eat framerate!  The 3-d panel is aimed at next-generation content.

ATTR_cockpit_region provides a new alternate panel texturing path that gets rid of legacy behavior for improved performance and image quality.

• ATTR_cockpit_region requires the region be a power of 2, which saves VRAM.  (If your panel is 1280×1024, then ATTR_cockpit rounds it to 2048×1024.  Yuck!)
• ATTR_cockpit_region grabs the lit and unlit elements of the panel separately, and can thus provide lighting that is consistent with the rest of OBJ.
• ATTR_cockpit_region does not preserve transparency (which isn’t a good way to model a 3-d cockpit performance wise) – removing the alpha feature improves framerate and saves VRAM.
• ATTR_cockpit_region lets you pick out parts of a panel to texture only what you need.

This last point is less important now that we have 3-d panels (ATTR_cockpit_region came first) – it was meant to let you pick out a small subset of a large size 2-d panel, skipping windows.  But if, for example, you need more than 1024×1024 pixels of panel texture, two cockpit regions are better than one 2048×1024 – some graphics cards hit a performance cliff when a cockpit or region exceeds 1024×1024.

(Under all situations, the instrument brightness rheostats should be preserved correctly.)

• The 3-d cockpit should look exactly like the 2-d cockpit.
• The 2-d panel is used as source.
• Panel transparency is preserved.
• Spot/flood lighting effects are available and work.
• Flood color is the forward flood color.
• The panel texture and object texture may not look the same under some lighting conditions.

ATTR_cockpit + 3-d panel:

• The 3-d panel is used as source.
• Transparency is preserved.
• Spot lights are not available, but flood flights work.
• Flood color is the side flood color.
• The panel texture and object texture may not look the same under some lighting conditions.

ATTR_cockpit_region + 2-d panel:

• The 2-d panel is used as source.
• Transparency is not available.
• Spot and flood lights are not available.
• Panel and object texture colors should match under all lighting conditions.

Basically both the 3-d panel and ATTR_cockpit_region are aimed at next-generation cockpits – they both strip legacy features to provide a clean platform for real 3-d cockpits.  The expectation is:

• Global lighting will be applied to all 3-d geometry – panel texture and object texture. Non-emissive lighting (spot lights, flood lights) will apply to everything.
• Windows will be built using geometry, not alpha.
• The panel texture can be minimized by packing a 3-d panel and using regions.  Manipulators let you provide interaction to regular object geometry.