NV2A/Pixel Combiner
From xboxdevwiki
The NV2A implements at least parts of the following OpenGL extensions:
- NV_texture_shader
- NV_texture_shader2
- NV_texture_shader3[citation needed]
- NV_register_combiners
- NV_register_combiners2
Data types
NV_texture_shader suggests that: "The 8-bit and 16-bit signed fixed-point types are used for signed internal texture formats, while the 9-bit signed fixed-point type is used for register combiners computations." Here is a table from the GL extension:
| floating-point | 8-bit fixed-point | 9-bit fixed-point | 16-bit fixed-point |
|---|---|---|---|
| 1.0 | n/a | 255 | n/a |
| 0.99996... | n/a | n/a | 32767 |
| 0.99218... | 127 | n/a | n/a |
| 0.0 | 0 | 0 | 0 |
| -1.0 | -128 | -255 | -32768 |
| -1.00392... | n/a | -256 | n/a |
This means:
- 8-bit fixed-point: [-128, 127] → [-128/128, 127/128] → [-1.0, 0.99218...]
- 9-bit fixed-point: [-256, 255] → [-256/255, 255/255] → [-1.00392..., 1.0]
- 16-bit fixed-point: [-32768, 32767] → [-32768/32768, 32767/32768] → [-1.0, 0.99996...]
It is not known if the NV2A really implements these 3 datatypes. It is also not yet known how exactly conversion or negation of these types would work.
Texturing modes
| ID | Name | GL Name | Stage 1 | Stage 2 | Stage 3 | Stage 4 | Notes |
|---|---|---|---|---|---|---|---|
| 0x00 | PS_TEXTUREMODES_NONE texcoord?[citation needed] |
NONE | ✔ | ✔ | ✔ | ✔ | |
| 0x01 | PS_TEXTUREMODES_PROJECT2D tex |
TEXTURE_2D | ✔ | ✔ | ✔ | ✔ | |
| 0x02 | PS_TEXTUREMODES_PROJECT3D | TEXTURE_3D | ✔ | ✔ | ✔ | ✔ | |
| 0x03 | PS_TEXTUREMODES_CUBEMAP | TEXTURE_CUBE_MAP_ARB | ✔ | ✔ | ✔ | ✔ | |
| 0x04 | PS_TEXTUREMODES_PASSTHRU texcoord?[citation needed] |
PASS_THROUGH_NV | ✔ | ✔ | ✔ | ✔ | |
| 0x05 | PS_TEXTUREMODES_CLIPPLANE texkill |
CULL_FRAGMENT_NV | ✔ | ✔ | ✔ | ✔ | |
| 0x06 | PS_TEXTUREMODES_BUMPENVMAP texbem |
OFFSET_TEXTURE_2D_NV | ✗ | ✔ | ✔ | ✔ | |
| 0x07 | PS_TEXTUREMODES_BUMPENVMAP_LUM texbeml |
OFFSET_TEXTURE_2D_SCALE_NV | ✗ | ✔ | ✔ | ✔ | |
| 0x08 | PS_TEXTUREMODES_BRDF texm3x2tex |
✗ | ✗ | ✔ | ✔ | ||
| 0x09 | PS_TEXTUREMODES_DOT_ST texm3x2pad?[citation needed] |
DOT_PRODUCT_NV[citation needed] | ✗ | ✗ | ✔ | ✔ | |
| 0x0A | PS_TEXTUREMODES_DOT_ZW texm3x2tex?[citation needed] |
DOT_PRODUCT_NV[citation needed] | ✗ | ✗ | ✔ | ✔ | |
| 0x0B | PS_TEXTUREMODES_DOT_RFLCT_DIFF | DOT_PRODUCT_DIFFUSE_CUBE_MAP_NV[citation needed] | ✗ | ✗ | ✔ | ✗ | |
| 0x0C | PS_TEXTUREMODES_DOT_RFLCT_SPEC | DOT_PRODUCT_CONST_EYE_REFLECT_CUBE_MAP_NV[citation needed] | ✗ | ✗ | ✗ | ✔ | |
| 0x0D | PS_TEXTUREMODES_DOT_STR_3D | DOT_PRODUCT_TEXTURE_3D_NV | ✗ | ✗ | ✗ | ✔ | |
| 0x0E | PS_TEXTUREMODES_DOT_STR_CUBE | DOT_PRODUCT_REFLECT_CUBE_MAP_NV | ✗ | ✗ | ✗ | ✔ | |
| 0x0F | PS_TEXTUREMODES_DPNDNT_AR texreg2ar |
DEPENDENT_AR_TEXTURE_2D_NV | ✗ | ✔ | ✔ | ✔ | |
| 0x10 | PS_TEXTUREMODES_DPNDNT_GB texreg2gb |
DEPENDENT_GB_TEXTURE_2D_NV | ✗ | ✔ | ✔ | ✔ | |
| 0x11 | PS_TEXTUREMODES_DOTPRODUCT | DOT_PRODUCT_NV | ✗ | ✔ | ✔ | ✗ | |
| 0x12 | PS_TEXTUREMODES_DOT_RFLCT_SPEC_CONST | DOT_PRODUCT_CONST_EYE_REFLECT_CUBE_MAP_NV | ✗ | ✗ | ✗ | ✔ |
Also known from nvidia docs:
- texm3x3pad [stage 1, stage 2]
- texm3x3spec [stage 3]
- texm3x3vspec [stage 3]
- texm3x3tex [stage 3]
Debugging
PIX from the Microsoft XDK provides great debugging capabilities.
