[PyQt] Creating a QSGGeometry.AttributeSet in PyQt5

Phil Thompson phil at riverbankcomputing.com
Sat Feb 22 14:33:20 GMT 2014

On 21-02-2014 1:08 pm, pwuertz wrote:
> Hi,
> I am trying to add a vertex array to a QSGGeometryNode for a custom 
> QtQuick
> Item. Qt5 uses QSGGeometry for that purpose and requires the user to 
> define
> a QSGGeometry.AttributeSet that describes structure of a vertex 
> array. There
> are a few pre-defined structures like the one from
> defaultAttributes_Point2D() but I need to create my own as described 
> in
> http://qt-project.org/doc/qt-5/qsggeometry.html.
> QSGGeometry::Attribute MyPoint2D_Attributes[] = {
>     QSGGeometry::Attribute::create(0, 2, GL_FLOAT, true),
>     QSGGeometry::Attribute::create(1, 4, GL_FLOAT, false)
> };
> QSGGeometry::AttributeSet MyPoint2D_AttributeSet = {
>     2,
>     sizeof(MyPoint2D),
>     MyPoint2D_Attributes
> };
> The problem is that I don't know how to create a 
> QSGGeometry.AttributeSet in
> PyQt5, which C++ creates by struct initialization. AttributeSet 
> doesn't have
> an initializing constructor and naively assigning a list of 
> Attributes to a
> default constructed instance fails because AttributeSet.attributes is
> read-only. How can I construct a complete AttributeSet in PyQt5?

Tonight's snapshot will have a AttributeSet ctor that takes a stride 
and a sequence of Attributes so that you can do...

attribute_set = QSGGeometry.AttributeSet(24,
     (QSGGeometry.Attribute.create(0, 2, QSGGeometry.GL_FLOAT, True),
      QSGGeometry.Attribute.create(1, 4, QSGGeometry.GL_FLOAT, True)))

It's very likely that there are other problems with the QSGGeometry 
API. Please let me know if you find other things that you need to be 
able to do but can't.


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