NV2A/Vertex attributes
This article documents the attribute types which are supported by the Xbox GPU. Please take everything with a grain of salt - it's still being researched.
Contents
- 1 Draw methods
- 1.1 Draw Arrays
- 1.2 Inline Buffer
- 1.2.1 NV097_SET_VERTEX_DATA2F_M ... NV097_SET_VERTEX_DATA2F_M + 0x7c
- 1.2.2 NV097_SET_VERTEX_DATA4F_M ... NV097_SET_VERTEX_DATA4F_M + 0xfc
- 1.2.3 NV097_SET_VERTEX_DATA2S ... NV097_SET_VERTEX_DATA2S + 0x3c
- 1.2.4 NV097_SET_VERTEX_DATA4UB ... NV097_SET_VERTEX_DATA4UB + 0x3c
- 1.2.5 NV097_SET_VERTEX_DATA4S_M ... NV097_SET_VERTEX_DATA4S_M + 0x7c
- 1.3 Inline Array
- 1.4 Inline Elements
- 2 Attribute Types
Draw methods
Draw Arrays
Data uploaded through DMA. Each attribute has it's own offset and stride. Decoded using the attribute information.
Inline Buffer
Data uploaded and decoded through PGRAPH methods.
NV097_SET_VERTEX_DATA2F_M ... NV097_SET_VERTEX_DATA2F_M + 0x7c
NV097_SET_VERTEX_DATA4F_M ... NV097_SET_VERTEX_DATA4F_M + 0xfc
NV097_SET_VERTEX_DATA2S ... NV097_SET_VERTEX_DATA2S + 0x3c
NV097_SET_VERTEX_DATA4UB ... NV097_SET_VERTEX_DATA4UB + 0x3c
NV097_SET_VERTEX_DATA4S_M ... NV097_SET_VERTEX_DATA4S_M + 0x7c
Inline Array
Data uploaded through PHRAPH method NV097_INLINE_ARRAY. The attributes are tightly packed in that buffer. Decoded using the attribute information.
Inline Elements
Same as "Draw Arrays" but with an extra index buffer. The index buffer is uploaded through PGRAPH methods NV097_ARRAY_ELEMENT16 and NV097_ARRAY_ELEMENT32.
Attribute Types
Normalized unsigned byte (D3D)
Unsigned bytes aranged as ZYXW (BGRA) in memory (Also see this GL extension). This is commonly used with an attribute count of 4. FIXME: Does this still work with attribute count =/= 4 ? Each byte will be mapped into the range 0.0 to 1.0. FIXME: Verify
Normalized unsigned byte (GL)
Unsigned bytes arranged as XYZW (RGBA) in memory. Each byte will be mapped into the range 0.0 to 1.0. FIXME: Verify
Normalized short
Shorts, arranged as XYZW. Each short will be mapped into the range -1.0 to 1.0 FIXME: Verify
Float
IEEE-754 single precision float arranged as XYZW. FIXME: What happens to NaN or denormals?
Short
Shorts, arranged as XYZW. Each short will be mapped into the range -32768.0 to 32767.0 FIXME: Verify
Compressed normal
Each 32 bit attribute is consisting of 11 bit X, 11 bit Y, 10 bit Z. Each component is signed and will be mapped into the range -1.0 to 1.0. FIXME: Verify FIXME: Is the attribute count ignored?
