# Popular Built-in VEX Attributes (Global Variables)

## General

| type  | name     | description                         |
| ----- | -------- | ----------------------------------- |
| int   | @ptnum   | Point Number                        |
| int   | @numpt   | Total number of points              |
| float | @Time    | Current time, in seconds            |
| float | @TimeInc | Time increment per frame in seconds |
| float | @Frame   | Current frame                       |
| int   | @primnum | Primitive Number                    |
| int   | @numprim | Total number of primitives          |
| int   | @vtxnum  | Vertex number                       |
| int   | @numvtx  | Total number of vertices            |

## Geometry

| type   | name       | description                                                        |
| ------ | ---------- | ------------------------------------------------------------------ |
| vec3   | @P         | Point/Primitive Position                                           |
| vec3   | @N         | Point/Primitive/Vertex Normal                                      |
| vec3   | @v         | Velocity (e.g. for motion blur / in particle systems)              |
| float  | @pscale    | Uniform scale. Used in copy-SOP or particle systems                |
| vec3   | @scale     | Non-Uniform scale. For use see pscale                              |
| vec3   | @up        | Up-Vector. Used together with @N to orient point/particle/instance |
| vec4   | @orient    | Quaternion defining the rotation of a point/particle/instance      |
| vec4   | @rot       | Quaternion defining additional rotation                            |
| vec3   | @trans     | Translation of instance                                            |
| matrix | @transform | Transformation matrix (used e.g. in Copy-SOP)                      |
| vec3   | @pivot     | Local pivot point for instance                                     |
| float  | @lod       | Detail/Primitive Level of detail                                   |
| vec3   | @rest      | Rest position                                                      |
| vec3   | @force     | Force (e.g. acting on particle)                                    |
| float  | @age       | Particle Age                                                       |
| float  | @life      | Max. Particle Life                                                 |

## Volumes

| type  | name          | description                                                            |
| ----- | ------------- | ---------------------------------------------------------------------- |
| float | @density      | Density of voxel                                                       |
| int   | @ix, @iy, @iz | Voxel indices along each axis. Ranging from 0 to resolution-1          |
| vec3  | @center       | Center of current Volume                                               |
| vec3  | @orig         | Bottom left corner of current Volume                                   |
| vec3  | @size         | Size of current Volume                                                 |
| vec3  | @dPdx         | Change in position to get from one voxel to the next in x direction    |
| vec3  | @dPdy         | Change in position to get from one voxel to the next in y direction    |
| vec3  | @dPdz         | Change in position to get from one voxel to the next in z direction    |
| vec3  | @BB           | relative position inside bounding box. Ranging from {0,0,0} to {1,1,1} |

## Shading

| type  | name     | description                 |
| ----- | -------- | --------------------------- |
| vec3  | @Vd      | Diffuse Color               |
| float | @Alpha   | Alpha transparency          |
| vec3  | @uv      | Point/Vertex UV coordinates |
| vec3  | @Cs      | Specular Color              |
| vec3  | @Cr      | Reflective Color            |
| vec3  | @Ct      | Transmissive Color          |
| vec3  | @Ce      | Emission Color              |
| float | @rough   | Roughness                   |
| float | @fresnel | Fresnel coefficient         |
| float | @shadow  | Shadow intensity            |
| float | @sbias   | Shadow bias                 |

## Used As Instancing Point Attribute in Copy-To-Point-SOP

| type   | name       | description                                                                             |
| ------ | ---------- | --------------------------------------------------------------------------------------- |
| vec3   | @P         | Instance Position                                                                       |
| float  | @pscale    | Uniform scale                                                                           |
| vec3   | @scale     | Non-Uniform scale                                                                       |
| vec3   | @N         | Normal (+Z axis of the copy, if no orient)                                              |
| vec3   | @up        | Up-Vector. Used together with @N to orient instance (+Y axis of the copy, if no orient) |
| vec4   | @orient    | Quaternion defining the rotation of a point/particle/instance                           |
| vec4   | @rot       | Quaternion defining additional rotation (applied after @orient)                         |
| vec3   | @v         | Velocity (motion blur, also used as +Z axis of the copy if no orient or N is present)   |
| vec3   | @trans     | Translation of instance                                                                 |
| matrix | @transform | Transformation matrix (used e.g. in Copy-SOP)                                           |
| vec3   | @pivot     | Local pivot point for instance                                                          |


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