User:MaxDZ8/Shader model Proto
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Shader models are functionality sets introduced in the various Direct3D releases. Because the term has seen widespread use and is often cited to final users, using the term to identify a specific hardware class is now commonplace.
This page actually covers only the effects of different shader models on shaders programming but a shader model usually introduces other functionalities as well, such as better precision, or instancing. Providing description of those features is left to a future revision of this document.
Hardware support for shading models
| Card (chip) | Vertex shader | Pixel shader |
|---|---|---|
| GeForce 3 (NV20) | 1.1 | 1.1 |
| Radeon 8500 up to 9200 (R200) | 1.1 | 1.4 |
| GeForce 4 Ti (NV25) | 1.1 | 1.3 |
| Parhelia | 2.0 | 1.3 |
| Radeon 9500 and later (R3xx) | 2.0 | 2.0 |
| Wildcat VP 10 | 1.1 | 1.2 |
| GeForce FX (NV30) | 2.a | 2.a |
| GeForce 6xxx (NV4x) | 3.0 | 3.0 |
| Radeon X800 (R4xx) | 2.0 | 2.b (1) |
|
(1): The 2.b pixel shader model is actually a subset of 2.a thus providing less functionality. | ||
Arithmetic instructions
How to read this table: dark gray means not available in this profile.
| Instruction mnemonic | Description | Used slots | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Vertex shader | Pixel shader | |||||||||
| 1.1-1.3 | 1.4 | 2.0 | 2.x | 3.0 | 1.1-1.3 | 1.4 | 2.0 | 3.0 | ||
| add | Add two vector registers | 1 | ||||||||
| abs | Absolute value | 1 | ||||||||
| crs | Cross product | 2 | ||||||||
| dp3, dp4 | Dot product of 3D or 4D vectors | 1 | ||||||||
| dst | Compute distance vector (???) | 1 | ||||||||
| exp/expp | 2x, full and partial precision. | 10/1 | 1/1 | |||||||
| frc | Fractional part | 3 | 1 | |||||||
| lrp | Linear interpolation of values. | 2 | ||||||||
| lit | ??? | 1 | 3??? | |||||||
| log/logp | log2(x), full and partial precision. | 10/1 | 1/1 | |||||||
| m3x2/m3x3/m3x4 | Multiply two 3xn matrices. | 2/3/4 | ||||||||
| m4x3/m4x4 | Multiply two 4xn matrices. | 3/4 | ||||||||
| mad | Multiply first two vectors, then add third one. | 1 | ||||||||
| min/max | Return component-wise min/max vector. | 1 | ||||||||
| mov | Move ??first?? to ??second?? | 1 | ||||||||
| mova | Move float value to address register. | 1 | ||||||||
| mul | Component-wise multiply | 1 | ||||||||
| nop | No operation. | 1 | ||||||||
| nrm | Normalize vector | 3 | ||||||||
| pow | xy | 3 | ||||||||
| rcp | Reciprocal. | 1 | ||||||||
| rsq | Reciprocal SQuare root. | 1 | ||||||||
| sincos | Optimized computation of both sine and cosine. | 8 | ||||||||
| sge | Set if greater or equal than. | 1 | ||||||||
| sgn | Sign | 3 | ||||||||
| slt | Set if less than. | 1 | ||||||||
| sub | Subtract. | 1 | ||||||||
Flow instructions
| Instruction mnemonic | Description | Used slots | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Vertex shader | Pixel shader | ||||||||
| 2.0 | 2.x | 3.0 | 1.1-1.3 | 1.4 | 2.0 | 3.0 | |||
| call | "Push IP and jump" to subroutine. | 2 | |||||||
| callnz bool | Conditional jump to subroutine if boolean register is not zero. | 3 | |||||||
| ret | Return from subroutine. | 1 | |||||||
| if bool | Execute block if condition is met. | 3 | |||||||
| else | Execute block if condition is not met. | 1 | |||||||
| endif | End of if/else instructions. | 1 | |||||||
| loop | Begin loop instruction block. | 3 | |||||||
| endloop | End of loop instruction block. | 2 | |||||||
| rep | Begin rep instruction block | 2 | |||||||
| endrep | End of rep instruction block. | 2 | |||||||
Setup instructions
All setup instructions take 0 slots.
| Instruction mnemonic | Description | Notes | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| dcl_usage_input | Bind vertex stream to input register. | |||||||||
| def | Define constant. | |||||||||
| defb | Define boolean constant (for static flow control). | Introduced in vs2.0 | ||||||||
| defi | Define integer constant (for static flow control). | Introduced in vs2.0 | ||||||||
| label | ??? | Introduced in vs2.0 | ||||||||
| vs | Declare profile, must be first instruction. | VS only | ||||||||
Vertex shader registers
All registers are four-component wide, unless otherwise noted. RIVEDERE QUESTA TABELLA
| Register mnemonic | Description | Count | Read/Write | Relative addressing | Notes | ||
|---|---|---|---|---|---|---|---|
| 1.1 | In | a0 | Address register | 14 | RW | No | Only .x write mask allowed in vs1.x, all 4 comps available on vs2 |
| aL | Loop register | 1 | Ro | No | Only .x write mask allowed in vs1.x, all 4 comps available on vs2 | ||
| cn | Float constant register | >96 (1) | Ro | Use a0.x | Default 0,0,0,0., INF read/ist in vs1.x, 2read/inst in vs2 | ||
| vn | Input register from vertex stream | 16 | Ro | No | Default 0,0,0,1. | ||
| rn | Temporary register | 12 | RW | No | Undefined, will cause error if read before initialization. | ||
| Out | ??? | ??? | ??? | ??? | ??? | ??? | |
Pixel shader registers
All registers are four-component wide, unless otherwise noted.
| Register mnemonic | Description | Count | Read/Write | Dimensionality | Notes | ||
|---|---|---|---|---|---|---|---|
| 1.1 | In | ??? | ??? | ??? | ??? | ??? | ??? |
| Out | oPos | Position register | 1 | Wo | 4D | ||
| oFog | Fog density register | 1 | Wo | 1D | |||
| oDn | Color register | 2 | Wo | 4D | oD0 is diffuse color, oD1 is specular. | ||
| oTn | Texcoord register | 8 | Wo | 4D | Indexable as oT[a0.x+n]. | ||
1.1 first released
2.0 static flow control, 4 cmp address reg, new ops, new regs
2.x dyn flow cntr, nesting, more temps, predication, new ops, new regs
3.0 tex lookups (samplers), indexable regs, 32tmps, new ops.
- ^ "Programming vertex and pixel shaders" by Wolfgang Engel, ISBN 1-58450-349-1.
- ^ Microsoft MSDN, Direct3D reference, the D3DCAPS9 and D3DPSHADERCAPS2_0 structures.