QSGTexture

The QSGTexture class is a baseclass for textures used in the scene graph. More

Inheritance diagram of PySide2.QtQuick.QSGTexture

Inherited by: QSGDynamicTexture

Synopsis

Functions

Virtual functions

Detailed Description

Users can freely implement their own texture classes to support arbitrary input textures, such as YUV video frames or 8 bit alpha masks. The scene graph backend provides a default implementation of normal color textures. As the implementation of these may be hardware specific, they are constructed via the factory function createTextureFromImage() .

The texture is a wrapper around an OpenGL texture, which texture id is given by textureId() and which size in pixels is given by textureSize() . hasAlphaChannel() reports if the texture contains opacity values and hasMipmaps() reports if the texture contains mipmap levels.

To use a texture, call the bind() function. The texture parameters specifying how the texture is bound, can be specified with setMipmapFiltering() , setFiltering() , setHorizontalWrapMode() and setVerticalWrapMode() . The texture will internally try to store these values to minimize the OpenGL state changes when the texture is bound.

Texture Atlasses

Some scene graph backends use texture atlasses, grouping multiple small textures into one large texture. If this is the case, the function isAtlasTexture() will return true. Atlasses are used to aid the rendering algorithm to do better sorting which increases performance. The location of the texture inside the atlas is given with the normalizedTextureSubRect() function.

If the texture is used in such a way that atlas is not preferable, the function removedFromAtlas() can be used to extract a non-atlassed copy.

Note

All classes with QSG prefix should be used solely on the scene graph’s rendering thread. See Scene Graph and Rendering for more information.

See also

Scene Graph - Rendering FBOs Scene Graph - Rendering FBOs in a thread

class PySide2.QtQuick.QSGTexture

Constructs the QSGTexture base class.

PySide2.QtQuick.QSGTexture.WrapMode

Specifies how the texture should treat texture coordinates.

Constant

Description

QSGTexture.Repeat

Only the fractional part of the texture coordinate is used, causing values above 1 and below 0 to repeat.

QSGTexture.ClampToEdge

Values above 1 are clamped to 1 and values below 0 are clamped to 0.

QSGTexture.MirroredRepeat

When the texture coordinate is even, only the fractional part is used. When odd, the texture coordinate is set to 1 - fractional part. This value has been introduced in Qt 5.10.

PySide2.QtQuick.QSGTexture.Filtering

Specifies how sampling of texels should filter when texture coordinates are not pixel aligned.

Constant

Description

QSGTexture.None

No filtering should occur. This value is only used together with setMipmapFiltering() .

QSGTexture.Nearest

Sampling returns the nearest texel.

QSGTexture.Linear

Sampling returns a linear interpolation of the neighboring texels.

PySide2.QtQuick.QSGTexture.AnisotropyLevel

Specifies the anisotropic filtering level to be used when the texture is not screen aligned.

Constant

Description

QSGTexture.AnisotropyNone

No anisotropic filtering.

QSGTexture.Anisotropy2x

2x anisotropic filtering.

QSGTexture.Anisotropy4x

4x anisotropic filtering.

QSGTexture.Anisotropy8x

8x anisotropic filtering.

QSGTexture.Anisotropy16x

16x anisotropic filtering.

New in version 5.9.

PySide2.QtQuick.QSGTexture.anisotropyLevel()
Return type

AnisotropyLevel

Returns the anisotropy level in use for filtering this texture.

PySide2.QtQuick.QSGTexture.bind()

Call this function to bind this texture to the current texture target.

Binding a texture may also include uploading the texture data from a previously set QImage .

Warning

This function should only be called when running with the direct OpenGL rendering path.

Warning

This function can only be called from the rendering thread.

PySide2.QtQuick.QSGTexture.comparisonKey()
Return type

int

Returns a key suitable for comparing textures. Typically used in compare() implementations.

Just comparing QSGTexture pointers is not always sufficient because two QSGTexture instances that refer to the same native texture object underneath should also be considered equal. Hence this function.

Note

Unlike textureId() , implementations of this function are not expected to and should not create any graphics resources (so texture objects) in case there is none yet.

A QSGTexture that does not have a native texture object underneath is typically not equal to any other QSGTexture . There are exceptions to this, in particular when atlasing is used (where multiple textures share the same atlas texture under the hood), that is then up to the subclass implementations to deal with as appropriate.

Warning

This function can only be called from the rendering thread.

PySide2.QtQuick.QSGTexture.convertToNormalizedSourceRect(rect)
Parameters

rectPySide2.QtCore.QRectF

Return type

PySide2.QtCore.QRectF

Returns rect converted to normalized coordinates.

PySide2.QtQuick.QSGTexture.filtering()
Return type

Filtering

Returns the sampling mode to be used for this texture.

See also

setFiltering()

PySide2.QtQuick.QSGTexture.hasAlphaChannel()
Return type

bool

Returns true if the texture data contains an alpha channel.

PySide2.QtQuick.QSGTexture.hasMipmaps()
Return type

bool

Returns true if the texture data contains mipmap levels.

PySide2.QtQuick.QSGTexture.horizontalWrapMode()
Return type

WrapMode

Returns the horizontal wrap mode to be used for this texture.

PySide2.QtQuick.QSGTexture.isAtlasTexture()
Return type

bool

Returns weither this texture is part of an atlas or not.

The default implementation returns false.

PySide2.QtQuick.QSGTexture.mipmapFiltering()
Return type

Filtering

Returns whether mipmapping should be used when sampling from this texture.

PySide2.QtQuick.QSGTexture.normalizedTextureSubRect()
Return type

PySide2.QtCore.QRectF

Returns the rectangle inside textureSize() that this texture represents in normalized coordinates.

The default implementation returns a rect at position (0, 0) with width and height of 1.

PySide2.QtQuick.QSGTexture.removedFromAtlas()
Return type

PySide2.QtQuick.QSGTexture

This function returns a copy of the current texture which is removed from its atlas.

The current texture remains unchanged, so texture coordinates do not need to be updated.

Removing a texture from an atlas is primarily useful when passing it to a shader that operates on the texture coordinates 0-1 instead of the texture subrect inside the atlas.

If the texture is not part of a texture atlas, this function returns 0.

Implementations of this function are recommended to return the same instance for multiple calls to limit memory usage.

Warning

This function can only be called from the rendering thread.

PySide2.QtQuick.QSGTexture.setAnisotropyLevel(level)
Parameters

levelAnisotropyLevel

Sets the level of anisotropic filtering to be used for the upcoming bind() call to level . The default value is AnisotropyNone , which means no anisotropic filtering is enabled.

PySide2.QtQuick.QSGTexture.setFiltering(filter)
Parameters

filterFiltering

Sets the sampling mode to be used for the upcoming bind() call to filter .

See also

filtering()

PySide2.QtQuick.QSGTexture.setHorizontalWrapMode(hwrap)
Parameters

hwrapWrapMode

Sets the horizontal wrap mode to be used for the upcoming bind() call to hwrap

PySide2.QtQuick.QSGTexture.setMipmapFiltering(filter)
Parameters

filterFiltering

Sets the mipmap sampling mode to be used for the upcoming bind() call to filter .

Setting the mipmap filtering has no effect it the texture does not have mipmaps.

PySide2.QtQuick.QSGTexture.setVerticalWrapMode(vwrap)
Parameters

vwrapWrapMode

Sets the vertical wrap mode to be used for the upcoming bind() call to vwrap

PySide2.QtQuick.QSGTexture.textureId()
Return type

int

Returns the OpenGL texture id for this texture.

The default value is 0, indicating that it is an invalid texture id.

The function should at all times return the correct texture id.

Warning

This function can only be called from the rendering thread.

PySide2.QtQuick.QSGTexture.textureSize()
Return type

PySide2.QtCore.QSize

Returns the size of the texture.

PySide2.QtQuick.QSGTexture.updateBindOptions([force=false])
Parameters

force – bool

Update the texture state to match the filtering, mipmap and wrap options currently set.

If force is true, all properties will be updated regardless of weither they have changed or not.

PySide2.QtQuick.QSGTexture.verticalWrapMode()
Return type

WrapMode

Returns the vertical wrap mode to be used for this texture.