Geometry Submission

Geometry Submission (IDX)

Offset	Description
0x100 .. 0x1FF	Attribute buffers memory base address and format description
0x120	Input/output buffers bit masks
0x121	Index buffer memory base address
0x122	Drawing config
0x123	Drawing elements number

Offset range 0x100 .. 0x1FF:

Two consecutive words are used to describe the input attribute buffer: first is memory address and latter is buffer format description. AR20 has total 16 input attribute buffers.

First word

Attribute buffer memory base address.

Bits	Meaning
0 .. 31	Memory base address

Latter word

Attribute buffer format description.

Bits	Meaning
0 .. 3	Attribute format
4 .. 6	Attribute size
8 .. 19	Attribute stride

Offset 0x120:

In / out buffers bit masks selects attribute input buffers that would be loaded from the DRAM into VPE and what output buffers would be allowed to be written by VS (to spare some clock cycles presumably).

Bits	Meaning
0 .. 15	Output buffers write-enable bit mask
16 .. 31	Input buffers read-enable bit mask

Offset 0x121:

Memory base address of the index buffer to be fetched into VPE.

Bits	Meaning
0 .. 31	Memory base address

Offset 0x122:

Drawing config, specifies how VPE should interpret input vertices's: triangles type / lines / points, use index buffer or not.

Bits	Meaning
24 .. 26	Primitive type
27	Flat-shade last
28 .. 29	Index buffer type

Offset 0x123:

Specifies drawing elements number.

Bits	Meaning
20 .. 31	Number + 1