Background Progress

I was going to write this last night, but I had to sleep early for a 7:30 AM dentist appointment...quite a start to the day.

As I wrote before, the DS has 4 different types of backgrounds: text, rotation, extended, and bitmap. Text backgrounds have about the same capability as what you'll find on the GBC or NES, while rotation backgrounds were very popular on the SNES.

As of now, I have text backgrounds working well; they render correctly, they scroll correctly, and my virtual memory mapper seems to be working well. I ran into a bug yesterday where I had loaded tile data into the sub core memory space, but no map data, and stuff was showing up on the sub core screen! To make it simpler, I was trying to get stuff to show up on both the screens; each screen has an associated core; the main core is the primary rendering core of the DS; it supports a few more styles, plus 3D...and can map more memory. The sub core is a secondary rendering core which has less memory at its disposal and lesser capabilities. Therefore, each core has its own virtual memory space, but for whatever reason, the sub core was taking data from the main core space. This was a bug in my virtual memory mapper; I wasn't doing a check correctly, so each memory read to this virtual memory space was always going through the main core.

My next task will be to read up on extended and rotation backgrounds; they seem pretty straightforward, albeit full of more features, so we'll see how that goes.