There are two ways to make 3-d instruments in your 3-d cockpit:
- Create 2-d instruments on a panel and use the “panel texture” (ATTR_cockpit or ATTR_cockpit_region in your OBJ) to show those 2-d instruments in the 3-d cockpit.
- Model the instruments in 3-d using animation.
So…which gives better framerate? Well, it turns out that they are actually almost the same…a few details:
- If your card can’t directly render-to-texture, there is an extra step for the panel texture. But that would be a weird case – all modern cards can render directly to textures unless you have hosed drivers.
- For very small amounts of geometry, there’s pretty much no difference between rotating a needle using the CPU and telling the GPU to do it by changing the coordinate system.
- The panel texture does put pressure on VRAM – if you’ve had to go to a 2048×2048 panel texture to have enough space, it’s going to hurt you.
A number of authors like the 3-d approach because they are more comfortable with 3-d tools, and because it can look sharper (since there is no intermediate limiting texture resolution).