Python

Assigning custom properties to vertexes

Working with mesh geometry, it may be necessary to assign each vertex some custom properties or data that must be written to the blend-file when saved, and which must be accessed later.

However, an attempt to assign the necessary data to the vertexes through the creation of custom properties fails. Instead of the custom vertex property, only a tuple with reference to the type of the property is created.

How to split and join Blender interface windows thruough the python API

A set of operators is provided in Blender for manipulating with the location of its interface windows.

To split the current window (using the current context) into two in a specified ratio, we need to execute the following operator:

With:

  • direction – set the splitting direction (‘HORIZONTAL’ or ‘VERTICAL’)
  • factor – percentage ratio of splitting windows

Custom property

The Blender API provides a set of simple property types described in bpy.props (IntProperty, BoolProperty, etc.). But the basic types are not always enough, sometimes we need more complex ones. The Blender API allows to group simple properties to make complex properties.

Let’s consider such complex property creation and make the 3×3 matrix property as an example.

Calling functions by pressing buttons in Blender custom UI

The button click is basically connected with the operator calling in the Blender user interface. However, some times actions, that need to be performed when a button is pressed, are quite simple and do not require a separate operator for them. And it makes no sense to fill a registered operators stack with a multitude of specific operators designed to perform one highly specialized function. It would be much more convenient to associate a button press with a separate function call but the Blender API allows to associate buttons only with an operator call.

To solve the problem of creating a separate operator for each button we can use the fact that the operator can be called with the input parameters.

How to get a list with all possible values of an EnumProperty

To correctly set values to an EnumProperty type we need to know all its possible entries.

If we try to set a value to an EnumProperty that is out of its available variants, Blender will throw an error:

TypeError: bpy_struct: item.attr = val: enum “xxx” not found in (‘value_001′, value_002’, …)

where:

xxx – the value we tried to set to an EnumProperty

value_001, value_002, … – possible EnumProperty values

How to move cursor to vertex

To translate cursor to the desired mesh vertex execute the following code:

Attention to the multiplication order – world matrix should be left.