Constants and limits

Constants at a glance

pad.*	twelve buttons, see the table in pad
gfx.FLIP_H gfx.FLIP_V	1, 2, flags of gfx.sprite
gfx.TILE_FLIP_H gfx.TILE_FLIP_V	0x400, 0x800, tile map entries
gfx.TILE_FONT16 gfx.TILE_FONT8 gfx.TILE_BLOCK	704, 960, 963, the system tiles
gfx.TRANSPARENT … gfx.BEHIND	0..5, modes of gfx.effect
phy.PX	65536, the unit of Q16.16 fixed point
phy.MASK phy.GRAVITY	actor flags
phy.LEFT phy.RIGHT phy.UP phy.DOWN	contacts of phy.touch
sys.TOUR	1024, one full turn for sys.sin

The gfx constants are described in gfx, the phy ones in phy, sys.TOUR in sys.

The limits the console imposes

display list	256 entries per frame
art pool	320 KiB, pages of 64 bytes; 16 loads and 96 KiB per frame
library (the bundle's art)	2 MiB in the simulator; the NOR flash of RP2 holds 16
bitmaps	1,024, system fonts included; 12 palettes, 16 backgrounds
compositing budget	16,000 cycles per scanline; beyond, the line is displayed stale
tile map	256 × 128 tiles; window 128 × 64; 624 bytes of writes per frame
actors	256
animations	64, of 32 images each
contacts per frame	256
collision mask	64 KiB
Lua heap	384 KiB
instructions per call	200,000, _update() and _draw() separately

These bounds are not whims: they are those of the hardware, measured on the board, or of RP1's SRAM budget. Exceeding one is reported with a number rather than discovered on screen. The display list, the pool, the library and the tile map are described in gfx; actors, animations, contacts and the collision mask in phy.