Hello, make sure you are using the shaders from the list below. The N3DS and 3DS use a Pica200 GPU it is compatible with Open GL ES 1.1 with some very limited functionality for 2.0.
what does that mean?
You have to use shader that where made before the GL 2.0 model which excludes most fragment shaders. AkA Unity's default shaders. Instead use...
- Mobile/Unlit (Supports Lightmap)
- Mobile/Particles/Additive
- Mobile/Particles/Alpha Blended
- Mobile/Particles/VertexLit Blended
- Mobile/Particles/Multiply
- Mobile/VertexLit
- Legacy Shaders/Transparent/VertexLit
- Legacy Shaders/Transparent/Cutout/VertexLit
- Legacy Shaders/Lightmapped/VertexLit
- Legacy Shaders/VertexLit
The basic rule is they must be shaders written as a fixed function shaders ( old unity 4 - 3 ) shaders / texture combiner shaders.
the List above should be ok for most simple projects..least to get your feet wet.
I should also warn you that its better to test on actual hardware than Citra. I have seen stuff work in Citra that dose not on the hardware. Also I notice that my tests have run much faster on hardware than Citra. A modified N3DS or N2DS with the FTPD software makes testing quick work. That said to get started and see if you want to dig deeper into development citra is a good start.
To answer the Texture question, yes the N3DS can handle up to 1024 that said you really want to be aiming more for a few 512's but more 256 and lower. The N3DS and N2DS only have 6MB of active Vram split between each screen so yeah that 3MB each. Now there is Device and system Memory which also is used for some texture storage but it is slower than the Vram. Now bare in mind when I say 6mb its 6 active mb so as long as your optimization conscious and turning stuff off when its not on screen you can pull it off. Also remember that the device your making a game for has a pair of small screen. Top: 400 x 240 and a Bottom: 320 x 240 you'd be surprised how much 256 gets you. Also make sure to use Nintendo's texture override settings to get Nintendo's texture compression format. it is magic at compressing textures. ETC 4 and 8 bit are the best choices.
hope this helps
oh and final note, Nice to see other people messing around with unity for the 3ds other than myself.