Rendering

Info

A frame rendering is achieved by creating a display list for everything that needs to be drawn for that frame. The completed display list is broken down into 4 different display lists:

• WORK_DISP - Seems to only branch directly to POLY_OPA_DISP
• POLY_OPA_DISP - Contains display lists for 3D polys/models without translucency(Opaque). Branches to POLY_XLU_DISP.
• POLY_XLU_DISP - Contains display lists for 3D polys/models with translucency. Branches to OVERLAY_DISP.
• OVERLAY_DISP - Contains display lists for 2D elements (like UI) that are overlaid over everything else.

These four display lists have their own buffers, which can be used to write display list commands programmatically. To do so, each has a "append start" pointer and "append end" pointer, as seen in the table below. The "append start" pointer points to the next free spot for display list commands. In order to append a new display list, you simply write your instructions starting at the "append start" pointer, then increment the pointer past your instructions. The "append end" pointer points to the address past the end of the remaining buffer. This pointer is used to append data for commands that are programmatically set during that frame. For example, the perspective and camera matrices (used to transform 3D models to a 2D space) change every frame. To add the matrix data, the "append end" address is decremented by 0x40 (the size of the matrix), then the matrix is stored at the new "append end" address.

Display list buffers should only be used to store instructions that cannot be pre-computed beforehand, since otherwise you'll be wasting cpu, time, and the limited buffer space.

Graphics Context

At Game Struct + 0x00 within all Game States is a pointer to a struct located on the "graph" thread stack that contains data used to assist in rendering.

Graphics Context

Offset	Type	Purpose	Other
0000	ptr	Working POLY_OPA_DISP start
0004	ptr	Working POLY_XLU_DISP start
0014	ptr	Working OVERLAY_DISP start
0038	OSMesg[8]	?	Referenced by 005C OsMesgQueue
005C	OSMesgQueue	?	First OSMesg at 0038
0088	int	?, set to 1
008C	int	?, set to 4
0090	ptr	Microcode Ptr	?
0094	int	Microcode Length	Length in bytes of the microcode sequence referenced by 0090
0098	ptr	Microcode Ptr	?
00B8	ptr	Completed WORK_DISP Start	branches to the DList task the RCP should be working on this cycle
00BC	int	Completed WORK_DISP Size
00C0	ptr	Unknown Buffer (0xC00) Start	mdump'ed as binary data. All 0s possibly due to emulation
00C4	int	Unknown Buffer (0xC00) Size
01B0	ptr	Working WORK_DISP Start
01B4	int	WORK_DISP Size	0x0400
01B8	ptr	WORK_DISP ptr
01BC	ptr	WORK_DISP append address	Used to append microcode instructions to the pipeline
01C0	ptr	WORK_DISP append end address	Used to store extra instruction data (matrix/movemem commands)
02A8	int	OVERLAY_DISP Size	0x2000 bytes
02AC	ptr	OVERLAY_DISP ptr
02B0	ptr	OVERLAY_DISP append address	Used to append microcode instructions to the pipeline
02B4	ptr	OVERLAY_DISP append end address	Used to store extra instruction data (matrix/movemem commands)
02B8	int	POLY_OPA_DISP Size	0xBF00 bytes
02BC	ptr	POLY_OPA_DISP ptr
02C0	ptr	POLY_OPA_DISP append address	Used to append microcode instructions to the pipeline
02C4	ptr	POLY_OPA_DISP append end address	Used to store extra instruction data (matrix/movemem commands)
02C8	int	POLY_XLU_DISP Size	0x4000 bytes
02CC	ptr	POLY_XLU_DISP ptr
02D0	ptr	POLY_XLU_DISP append address	Used to append microcode instructions to the pipeline
02D4	ptr	POLY_XLU_DISP append end address	Used to store extra instruction data (matrix/movemem commands)
02D8	int	Frame Counter 1	Used for swapping display list buffers
02DC	ptr	Working Framebuffer
02E8	int	Frame Counter 2	Used for swapping framebuffers
02EC	ptr	Function Pointer	?
02F0	ptr	Global Context