Vertex Elements — The Mesa 3D Graphics Library latest documentation

# Vertex Elements

This state controls the format of the input attributes contained in pipe_vertex_buffers. There is one pipe_vertex_element array member for each input attribute.

## Input Formats

Gallium supports a diverse range of formats for vertex data. Drivers are guaranteed to support 32-bit floating-point vectors of one to four components. Additionally, they may support the following formats:

- Integers, signed or unsigned, normalized or non-normalized, 8, 16, or 32 bits wide

- Floating-point, 16, 32, or 64 bits wide

At this time, support for varied vertex data formats is limited by driver deficiencies. It is planned to support a single uniform set of formats for all Gallium drivers at some point.

Rather than attempt to specify every small nuance of behavior, Gallium uses a very simple set of rules for padding out unspecified components. If an input uses less than four components, it will be padded out with the constant vector `(0, 0, 0, 1)`.

Fog, point size, the facing bit, and edge flags, all are in the standard format of `(x, 0, 0, 1)`, and so only the first component of those inputs is used.

### Position

Vertex position may be specified with two to four components. Using less than two components is not allowed.

### Colors

Colors, both front- and back-facing, may omit the alpha component, only using three components. Using less than three components is not allowed.

## Members

src_offset

  The byte offset of the attribute in the buffer given by vertex_buffer_index for the first vertex.

instance_divisor

  The instance data rate divisor, used for instancing. 0 means this is per-vertex data, n means per-instance data used for n consecutive instances (n > 0).

vertex_buffer_index

  The vertex buffer this attribute lives in. Several attributes may live in the same vertex buffer.

src_format

  The format of the attribute data. One of the PIPE_FORMAT tokens.