What's the reason for the fixed limit on polys/scene in the DS?

[Simon F]

And it doesn't end there - there's texture compression which again - is quite different from the approaches that have been common for past 10 years. Actually I'd love to hear Simon's take on this one - since it's still VQ based approach, but with a pretty strange spin on it.

Gosh I completely missed this comment when it came past the first time. Where could I find info on the DS texture compression?

EDIT: The power of Google:

About the texture compression, we know it's VQ, but not regular palette based. Can you tell us more?Basically it's S3TC with detached color tables. Each texel block carries extra overhead - a pointer(16bit) to address it's associated CLUT, which allows CLUT data to be shared between blocks as well as across any number of textures (including regular paletted ones).
Also offers the choice between 2+2 and 4 distinct colors in each block, which helps with textures where S3TC sucks the worst (sharp color transitions, hand drawn art...).

The 16-bit pointer: Is that going to a 4 colour palette?

If the blocks are 4x4 pixels with choice of four colours/pixel, that would then seem to indicate that blocks are 48bits in size. That would be bizarre!

 

[Fafalada]

If the blocks are 4x4 pixels with choice of four colours/pixel, that would then seem to indicate that blocks are 48bits in size. That would be bizarre!

You're right, that would be bizarre (although Nintendo did use 24bit addressing in GC in the past, so weirder things have happened).
In this case though, they get stored into separate banks(DS VRam has many banks ), and you have to obey the size ratio for addresses you put them in (eg. address "A", and "A/2" respectively).

Yea I know, and some people thought PS2 memory layout was complicated...

I was curious though what your thoughts are on having common palette storage for all your textures like this (it also allows mixing regular 8/4bit Clut palettes in the same area). I know there's nice potential savings in specific cases, but I can't say I know whether this is a worthwhile benefit for general cases (especially stuff like photographic imagery).