Events
May 19, 6 PM - May 23, 12 AM
Calling all developers, creators, and AI innovators to join us in Seattle @Microsoft Build May 19-22.
Register todayNote
Access to this page requires authorization. You can try signing in or changing directories.
Access to this page requires authorization. You can try changing directories.
Pixel shaders depend on registers to get vertex data, to output pixel data, to hold temporary results during calculations, and to identify texture sampling stages. There are several types of registers, each with a unique functionality. This section contains reference information for the input and output registers implemented by pixel shader version 2_x.
| Register | Name | Count | R/W | # Read ports | # Reads/inst | Dimension | RelAddr | Defaults | Requires DCL |
|---|---|---|---|---|---|---|---|---|---|
| v# | Input Color Register | 2 | R | 1 | Unlimited | 4 | N | Partial(0001). See note 4 | Y |
| r# | Temporary Register | See note 1 | R/W | 3 | Unlimited | 4 | N | None | N |
| c# | Constant Float Register | 32 | R | 1 | 2 | 4 | N | 0000 | N |
| i# | Constant Integer Register | 16 | See note 2 | 1 | 1 | 4 | N | 0000 | N |
| b# | Constant Boolean Register | 16 | See note 2 | 1 | 1 | 1 | N | FALSE | N |
| p0 | Predicate Register | 1 | See note 2 | 1 | 1 | 1 | N | None | Y |
| s# | Sampler (Direct3D 9 asm-ps) | 16 | See note 3 | 1 | 1 | 4 | N | See note 5 | Y |
| t# | Texture Coordinate Register | 8 | R | 1 | 1 | 4 | N | None | Y |
Notes:
- 12 min/32 max: The number of r# registers is determined by D3DPSHADERCAPS2_0.NumTemps (which ranges from 12 to 32).
- Only usable by a flow control instruction.
- Only usable by a texture sampling instruction.
- partial(x, y, z, w) - If only a subset of channels are updated in the register, the remaining channels will default to specified values (x, y, z, w).
- Defaults for sampler lookups exist, but values depend on texture format.
The number of readports is the number of different registers (for each register type) that can be read in a single instruction.
| Register | Name | Count | R/W | Dimension | RelAddr | Defaults | Requires DCL |
|---|---|---|---|---|---|---|---|
| oC# | Output Color Register | See Multiple-element Textures (Direct3D 9) | W | 4 | N | None | N |
| oDepth | Output Depth Register | 1 | W | 1 | N | None | N |