GPU/GL Arrays

This page describes the GPU commands used for OpenGL arrays.

Command Sets

glDrawElements()

Command Index	CommandID	Parameter	Description
0	0x0229	u32, val<<8.	Unknown, val is 0 or 1.
1-2	0x0253	Same as command 0x0229.	Unknown
3	0x025E	u32, val<<8.	This sets the GL rendering mode.
4	0x025E	Value 0	?
5	0x025F	Value 1	?
6	0x0253	Value 0	?
7	0x0227	u32	This specifies the indices data-type, and the indices array address.
8	0x0228	u32	This specifies the number of elements in the array to use for rendering.
9	0x0245	Value 0	?
10	0x022F	Value 1	?
11	0x0245	Value 1	?
12	0x0231	Value 1	?
13	0x0111	Value 1	?
14	0x0229	Value 0	?
15	0x0253	Value 0	?
16	0x025E	Value 0	?
17	0x02BA	Value 0x7FFF0000	?

Command 0x0200

Command Index	CommandID	Parameter	Description
0	0x0200		This sets the addresses for the GL arrays.
1	0x02BB		?
2	0x0232		Unknown, this command is used multiple times for specifying each parameter-buffer entry.

GL mode values for command 0x025E

Value	Description
0	GL_TRIANGLES
1	GL_TRIANGLE_STRIP
2	GL_TRIANGLE_FAN
3	Unknown. An unconfirmed theory is that this is used for variable-size primitives (GL_SUBD_PRIM_DMP/GL_GEOMETRY_PRIMITIVE_DMP), for which the index buffer format is altered slightly (each sequence of indices constituting a primitive is prepended a number indicating the primitive size).
4	Unknown, this seems to have the same effect as value 0.

Parameter value format for command 0x0227

Bit	Description
30-0	Indices array address, relative to base set with command 0x0200.
31	0 = indices data-type GL_UNSIGNED_BYTE, 1 = GL_UNSIGNED_SHORT.

Parameter structure for command 0x0200

Index Word	Description
0x0	Base physical address >> 3, normally located in VRAM. The address must be aligned to a 16-byte boundary.
0x1	Every 4 bits is used for specifying the array data-type and size for each entry.
0x2	Value is: (0xF0000000 + (val<<28)) | ((attrib_mask & 0xFFF)<<16), where val is the total 4-bit value entries for the command 0x801F02BB parameter buffer.(Normally val is 8); attrib_mask is usually (0xFFF<<totalentries)
0x3-0x26	12 entries, each entry is 3 words.

These parameters and the entries' parameters are set by gl*Pointer().

Entry structure

Index Word	Description
0	Physical address, relative to the base address.
1	Entry attribute permutation (lower 8 bytes)
2	Value is: ((numattrib)<<28 | (stride<<16) | ((attrib_permuation>>32)&0xFFFF). (stride in bytes)

A given entry corresponds to a buffer, but a single buffer may contain attributes of multiple different interlaced attributes, hence the attribute permutation parameter which lists the various attributes that can be found in the buffer, and in which order. If stride doesn't exactly match the format, the GPU may hang. When the entry is unused, the entry data is all-zero.

Array data-type/size values

Value	GL type
0x0 + ((size-1)*4)	GL_BYTE
0x1 + ((size-1)*4)	GL_UNSIGNED_BYTE
0x2 + ((size-1)*4)	GL_UNSIGNED_SHORT/GL_SHORT
0x3 + ((size-1)*4)	GL_FLOAT

Size is 1-4. Using GL_FLOAT with a texture coordinates array causes the GPU to hang?

Parameter structure for command 0x02BB

Index Word	Description
0-1	u64, every 4-bits is a value from some array.

Parameter structure for command 0x0232

Index Word	Description
0	Entry index + total command 0x0200 parameter-buffer entries.
1	Unknown, usually value 0x3F000000 / 0.5f.(u32 read/writes are used for this field, not float read/writes however)
2	Unknown, usually value 0.
3	Unknown, usually value 0.

Each parameter buffer for command 0x0232 is an entry loaded from an array. 4 float24 values ?