- Qt 6.8
- Qt GUI
- C++ Classes
- QtGuiPrivate
- QRhiVertexInputAttribute
- Qt 6.8.2 Reference Documentation

# QRhiVertexInputAttribute Class

Describes a single vertex input element. More...

Header: | `#include <rhi/qrhi.h>`
CMake: | `find_package(Qt6 REQUIRED COMPONENTS Gui)` `target_link_libraries(mytarget PRIVATE Qt6::GuiPrivate)`
qmake: | `QT += gui-private`
Since: | Qt 6.6

- List of all members, including inherited members

## Public Types

enum | Format { Float4, Float3, Float2, Float, UNormByte4, …, SShort }

## Public Functions

| QRhiVertexInputAttribute()
| QRhiVertexInputAttribute(int binding, int location, QRhiVertexInputAttribute::Format format, quint32 offset, int matrixSlice = -1)
int | binding() const
QRhiVertexInputAttribute::Format | format() const
int | location() const
int | matrixSlice() const
quint32 | offset() const
void | setBinding(int b)
void | setFormat(QRhiVertexInputAttribute::Format f)
void | setLocation(int loc)
void | setMatrixSlice(int slice)
void | setOffset(quint32 ofs)

## Related Non-Members

size_t | qHash(const QRhiVertexInputAttribute &key, size_t seed = 0)
bool | operator!=(const QRhiVertexInputAttribute &a, const QRhiVertexInputAttribute &b)
bool | operator==(const QRhiVertexInputAttribute &a, const QRhiVertexInputAttribute &b)

## Detailed Description

The members specify the binding number, location, format, and offset for a single vertex input element.

Note: For HLSL it is assumed that the vertex shader translated from SPIR-V uses `TEXCOORD<location>` as the semantic for each input. Hence no separate semantic name and index.

As an example, assume a vertex shader with the following inputs:

     layout(location = 0) in vec4 position;
     layout(location = 1) in vec2 texcoord;

Now let's assume that we have 3 component vertex positions `(x, y, z)` and 2 component texture coordinates `(u, v)` are provided in a non-interleaved format in a buffer (or separate buffers even). Once two bindings are defined, the attributes could be specified as:

     QRhiVertexInputLayout inputLayout;
     inputLayout.setBindings({
         { 3 * sizeof(float) },
         { 2 * sizeof(float) }
     });
     inputLayout.setAttributes({
         { 0, 0, QRhiVertexInputAttribute::Float3, 0 },
         { 1, 1, QRhiVertexInputAttribute::Float2, 0 }
     });

Once a graphics pipeline with this vertex input layout is bound, the vertex inputs could be set up like the following for drawing a cube with 36 vertices, assuming we have a single buffer with first the positions and then the texture coordinates:

     const QRhiCommandBuffer::VertexInput vbufBindings[] = {
         { cubeBuf, 0 },
         { cubeBuf, 36 * 3 * sizeof(float) }
     };
     cb->setVertexInput(0, 2, vbufBindings);

When working with interleaved data, there will typically be just one binding, with multiple attributes referring to that same buffer binding point:

     QRhiVertexInputLayout inputLayout;
     inputLayout.setBindings({
         { 5 * sizeof(float) }
     });
     inputLayout.setAttributes({
         { 0, 0, QRhiVertexInputAttribute::Float3, 0 },
         { 0, 1, QRhiVertexInputAttribute::Float2, 3 * sizeof(float) }
     });

and then:

     const QRhiCommandBuffer::VertexInput vbufBinding(interleavedCubeBuf, 0);
     cb->setVertexInput(0, 1, &vbufBinding);

Note: This is a RHI API with limited compatibility guarantees, see QRhi for details.

See also QRhiCommandBuffer::setVertexInput().

## Member Type Documentation

### enum QRhiVertexInputAttribute::Format

Specifies the type of the element data.

Constant | Value | Description
--- | --- | ---
`QRhiVertexInputAttribute::Float4` | `0` | Four component float vector
`QRhiVertexInputAttribute::Float3` | `1` | Three component float vector
`QRhiVertexInputAttribute::Float2` | `2` | Two component float vector
`QRhiVertexInputAttribute::Float` | `3` | Float
`QRhiVertexInputAttribute::UNormByte4` | `4` | Four component normalized unsigned byte vector
`QRhiVertexInputAttribute::UNormByte2` | `5` | Two component normalized unsigned byte vector
`QRhiVertexInputAttribute::UNormByte` | `6` | Normalized unsigned byte
`QRhiVertexInputAttribute::UInt4` | `7` | Four component unsigned integer vector
`QRhiVertexInputAttribute::UInt3` | `8` | Three component unsigned integer vector
`QRhiVertexInputAttribute::UInt2` | `9` | Two component unsigned integer vector
`QRhiVertexInputAttribute::UInt` | `10` | Unsigned integer
`QRhiVertexInputAttribute::SInt4` | `11` | Four component signed integer vector
`QRhiVertexInputAttribute::SInt3` | `12` | Three component signed integer vector
`QRhiVertexInputAttribute::SInt2` | `13` | Two component signed integer vector
`QRhiVertexInputAttribute::SInt` | `14` | Signed integer
`QRhiVertexInputAttribute::Half4` | `15` | Four component half precision (16 bit) float vector
`QRhiVertexInputAttribute::Half3` | `16` | Three component half precision (16 bit) float vector
`QRhiVertexInputAttribute::Half2` | `17` | Two component half precision (16 bit) float vector
`QRhiVertexInputAttribute::Half` | `18` | Half precision (16 bit) float
`QRhiVertexInputAttribute::UShort4` | `19` | Four component unsigned short (16 bit) integer vector
`QRhiVertexInputAttribute::UShort3` | `20` | Three component unsigned short (16 bit) integer vector
`QRhiVertexInputAttribute::UShort2` | `21` | Two component unsigned short (16 bit) integer vector
`QRhiVertexInputAttribute::UShort` | `22` | Unsigned short (16 bit) integer
`QRhiVertexInputAttribute::SShort4` | `23` | Four component signed short (16 bit) integer vector
`QRhiVertexInputAttribute::SShort3` | `24` | Three component signed short (16 bit) integer vector
`QRhiVertexInputAttribute::SShort2` | `25` | Two component signed short (16 bit) integer vector
`QRhiVertexInputAttribute::SShort` | `26` | Signed short (16 bit) integer

Note: Support for half precision floating point attributes is indicated at run time by the QRhi::Feature::HalfAttributes feature flag.

Note: Direct3D 11/12 supports 16 bit input attributes, but does not support the Half3, UShort3 or SShort3 types. The D3D backends pass through Half3 as Half4, UShort3 as UShort4, and SShort3 as SShort4. To ensure cross platform compatibility, 16 bit inputs should be padded to 8 bytes.

## Member Function Documentation

### `[constexpr noexcept]` QRhiVertexInputAttribute::QRhiVertexInputAttribute()

Constructs a default vertex input attribute description.

### QRhiVertexInputAttribute::QRhiVertexInputAttribute(int binding, int location, QRhiVertexInputAttribute::Format format, quint32 offset, int matrixSlice = -1)

Constructs a vertex input attribute description with the specified binding number, location, format, and offset.

matrixSlice should be -1 except when this attribute corresponds to a row or column of a matrix (for example, a 4x4 matrix becomes 4 vec4s, consuming 4 consecutive vertex input locations), in which case it is the index of the row or column. `location - matrixSlice` must always be equal to the `location` for the first row or column of the unrolled matrix.

### int QRhiVertexInputAttribute::binding() const

Returns the binding point index.

See also setBinding().

### QRhiVertexInputAttribute::Format QRhiVertexInputAttribute::format() const

Returns the format of the vertex input element.

See also setFormat().

### int QRhiVertexInputAttribute::location() const

Returns the location of the vertex input element.

See also setLocation().

### int QRhiVertexInputAttribute::matrixSlice() const

Returns the matrix slice if the input element corresponds to a row or column of a matrix, or -1 if not relevant.

See also setMatrixSlice().

### quint32 QRhiVertexInputAttribute::offset() const

Returns the byte offset for the input element.

See also setOffset().

### void QRhiVertexInputAttribute::setBinding(int b)

Sets the binding point index to b. By default this is set to 0.

See also binding().

### void QRhiVertexInputAttribute::setFormat(QRhiVertexInputAttribute::Format f)

Sets the format of the vertex input element to f. By default this is set to Float4.

See also format().

### void QRhiVertexInputAttribute::setLocation(int loc)

Sets the location of the vertex input element to loc. By default this is set to 0.

See also location().

### void QRhiVertexInputAttribute::setMatrixSlice(int slice)

Sets the matrix slice. By default this is set to -1, and should be set to a >= 0 value only when this attribute corresponds to a row or column of a matrix (for example, a 4x4 matrix becomes 4 vec4s, consuming 4 consecutive vertex input locations), in which case it is the index of the row or column. `location - matrixSlice` must always be equal to the `location` for the first row or column of the unrolled matrix.

See also matrixSlice().

### void QRhiVertexInputAttribute::setOffset(quint32 ofs)

Sets the byte offset for the input element to ofs.

See also offset().

## Related Non-Members

### `[noexcept]` size_t qHash(const QRhiVertexInputAttribute &key, size_t seed = 0)

Returns the hash value for key, using seed to seed the calculation.

### `[noexcept]` bool operator!=(const QRhiVertexInputAttribute &a, const QRhiVertexInputAttribute &b)

Returns `false` if the values in the two QRhiVertexInputAttribute objects a and b are equal; otherwise returns `true`.

### `[noexcept]` bool operator==(const QRhiVertexInputAttribute &a, const QRhiVertexInputAttribute &b)

Returns `true` if the values in the two QRhiVertexInputAttribute objects a and b are equal.