Research: Let's research the OAM-System

00000000 [B]coords[/B]              struc @ (sizeof=0x4)
00000000 [COLOR="Red"]x[/COLOR]:                  .short
00000002 [COLOR="Blue"]y[/COLOR]:                  .short
00000004 coords              ends

[COLOR="Orange"]00000000[/COLOR] [B]oam[/B]                 struc @ (sizeof=0x8)
[COLOR="orange"]00000000[/COLOR] y:                  .byte
[COLOR="orange"]00000001[/COLOR] flags1:             .byte
[COLOR="orange"]00000002[/COLOR] x:                  .byte
[COLOR="orange"]00000003[/COLOR] msb_of_x_and_flags2:.byte
[COLOR="orange"]00000004[/COLOR] tile_prio_pal:      .short
[COLOR="orange"]00000006[/COLOR] irrelevant:         .short
[COLOR="orange"]00000008[/COLOR] oam                 ends

00000000 [B]animation[/B]           struc @ (sizeof=0x4)
00000000 frame:              .half @ Internally: 0xFFFD=>animcmd1 0xFFFE=>animcmd2
00000000                           @ 0xFFFF=>animcmd3 any other number (=framenr) =>animcmd4
00000002 duration:           .half
00000004 animation           ends
(read [url]http://www.pokecommunity.com/showthread.php?t=236456[/url] for details)

[COLOR="Lime"]00000000[/COLOR] [B]object_template[/B]     struc @ (sizeof=0x18)
[COLOR="lime"]00000000[/COLOR] tiles_tag:          .short
[COLOR="lime"]00000002[/COLOR] pal_tag:            .short
[COLOR="lime"]00000004[/COLOR] oam:                .long
[COLOR="lime"]00000008[/COLOR] [U]image_table[/U]:        .long
[COLOR="lime"]0000000C[/COLOR] gfx_table:          .long
[COLOR="lime"]00000010[/COLOR] rotscale_table:     .long
[COLOR="lime"]00000014[/COLOR] [U]callback[/U]:           .long
[COLOR="lime"]00000018[/COLOR] object_template     ends

[COLOR="Sienna"]00000000[/COLOR] [B]object[/B]         struc @ (sizeof=0x44)
[COLOR="sienna"]00000000[/COLOR] [COLOR="Orange"]final_oam[/COLOR]:          oam
[COLOR="sienna"]00000008[/COLOR] [U]animation_table[/U]:    .long
[COLOR="sienna"]0000000C[/COLOR] gfx_table:          .long
[COLOR="sienna"]00000010[/COLOR] rotscale_table:     .long
[COLOR="sienna"]00000014[/COLOR] [COLOR="Lime"][U]template[/U][/COLOR]: .long
[COLOR="sienna"]00000018[/COLOR] field_18:           .long
[COLOR="sienna"]0000001C[/COLOR] [U]callback[/U]:           .long
[COLOR="sienna"]00000020[/COLOR] pos_1:              [COLOR="red"]coo[/COLOR][COLOR="Blue"]rds[/COLOR]
[COLOR="sienna"]00000024[/COLOR] pos_2:              [COLOR="red"]coo[/COLOR][COLOR="blue"]rds[/COLOR]
[COLOR="sienna"]00000028[/COLOR] [COLOR="Red"]pos_3_x[/COLOR]:            .byte  @ These coordinates are [u]subtracted[/u] from actual position!
[COLOR="sienna"]00000029[/COLOR] [COLOR="blue"]pos_3_y[/COLOR]:            .byte  @ It is used to center the sprites. So most of the times pos_3_x=width/2 and pos_3_y=height/2
[COLOR="sienna"]0000002A[/COLOR] anim_nr:            .byte
[COLOR="sienna"]0000002B[/COLOR] anim_frame:         .byte
[COLOR="sienna"]0000002C[/COLOR] anim_delay_countdown:      .byte @ six bits acting as countdown. two upper bits can pause image and rotscale-animations
[COLOR="sienna"]0000002D[/COLOR] field_2D:           .byte
[COLOR="sienna"]0000002E[/COLOR] ipos:               [COLOR="red"]coo[/COLOR][COLOR="Blue"]rds[/COLOR] ?
[COLOR="sienna"]00000032[/COLOR] ivel:               [COLOR="red"]coo[/COLOR][COLOR="Blue"]rds[/COLOR] ?            @ It seems like this is the private area
[COLOR="sienna"]00000032[/COLOR]                                         @ for functions managing a single oam.
[COLOR="sienna"]00000032[/COLOR]                                         @ Moving objects use ipos and ivel to save
[COLOR="sienna"]00000032[/COLOR]                                         @ the position and velocity. But they have
[COLOR="sienna"]00000032[/COLOR]                                         @ to be transferred to pos_1 manually. And
[COLOR="sienna"]00000032[/COLOR]                                         @ NPCs use the first byte of ivel to store
[COLOR="sienna"]00000032[/COLOR]                                         @ their current state.
...
[COLOR="sienna"]00000042[/COLOR] field_42:           .byte
[COLOR="sienna"]00000043[/COLOR] field_43:           .byte
[COLOR="sienna"]00000044[/COLOR] object         ends

00000000 [B]npc_state[/B]       struc @ (sizeof=0x24)
00000000 bitfield_DX:    .byte ?
00000001 field_1:        .byte ?
00000002 field_2:        .byte ?
00000003 field_3:        .byte ?
00000004 oamid:          .byte ?
00000005 typeid:         .byte ?          @ Used as index for gender-color-lookup
00000006 running_behaviour:.byte ?
00000007 is_trainer:     .byte ?
00000008 field_8:        .byte ?
00000009 field_9:        .byte ?
0000000A field_A:        .byte ?
0000000B height:         .byte ?          @ Only bits 0x0F define height. I don't know about 0xF0.
0000000C stay_around:    coords ?
00000010 from:           coords ?
00000014 to:             coords ?
00000018 unknown2:       .byte ?
00000019 movement_area:  .byte ?
0000001A field_1A:       .short ?
0000001C the_state:      .byte ?
0000001D sight_distance: .byte ?
0000001E tile_from:      .byte ?
0000001F tile_to:        .byte ?
00000020 unknown1:       .byte ?
00000021 unknown3:       .byte ?
00000022 field_22:       .byte ?
00000023 field_23:       .byte ?
00000024 npc_state       ends

0840BC2C oam_star:       oam <0, 0, 0, 0x40, 0x800, 0>
0840BC34 oam_sparks:     oam <0, 0, 0, 0, 0x800, 0>
0840BC3C anim_spark_1:   animation <0, 0,  4, 0> @ 0
0840BC3C                 animation < 1, 0,  4, 0>@ 1
0840BC3C                 animation < 2, 0,  4, 0>@ 2
0840BC3C                 animation < 3, 0,  4, 0>@ 3
0840BC3C                 animation <0xFE, 0xFF, 0, 0>@ 4
0840BC50 anim_spark_2:   animation <0, 0,  4, 0> @ 0
0840BC50                 animation < 1, 0,  4, 0>@ 1
0840BC50                 animation < 2, 0,  4, 0>@ 2
0840BC50                 animation < 3, 0,  4, 0>@ 3
0840BC50                 animation <0xFF, 0xFF, 0, 0>@ 4
0840BC64 animtable_sparks:.long anim_spark_1,anim_spark_2@ 0
0840BC6C tpl_star:       object_template <0, 0, oam_star, animtable_empty, 0, off_08231CFC, oac_star+1>
0840BC84 tpl_sparks:     object_template <1, 1, oam_sparks, animtable_sparks, 0, off_08231CFC, oac_sparks+1>