General construction considerations
-----------------------------------

Use real-world units
Consider where slice boundaries will be
Box and fuselage geometries can be used to visualize placement of components
Define sets to limit which geometries get analyzed and exported etc
If you create cylinders for visualization like I did in the video, they MUST 
	be excluded from VSPAERO analysis or the program will crash



Preparing for export from OpenVSP
---------------------------------

Increase tesselation resolution on wing, fuselage etc geoms that will become the STL model
Convert airfoils to CST parametrization if necessary to have the "Equal arc length" checkbox
	This cannot be undone! Either make a backup or don't save after making this change
	if you want to go back to the original airfoil definition parameters!
Uncheck "Equal arc length parameterization" to cluster more points around leading edge
Do "Analysis" -> "Planar slice"
	normal = Y-axis, num slices = (end location / slice thickness) + 1
Export shown set to stl



In Blender
----------

File -> Import -> STL (may need to enable add-on in Edit -> Preferences dialog)
Press S to scale if necessary, hold ctrl to scale in steps

Press tab to switch between editing objects and meshes
Select all non-slice parts and move away (press L with mouse over a vertex to select entire mesh)
Press G to start moving, then X and hold ctrl to move in steps along X axis
Press P to separate by selection

In object edit mode, press space and use menu to add cylinder
Press S to scale if necessary, hold ctrl to scale in steps
Press R then X and hold ctrl to rotate in steps about the X axis
Press S then Y to scale the cylinder only along the Y axis
Move spar into position

Add spars as necessary, Shift+D to duplicate

To make holes in the slices, select the slice object, add boolean modifer (spanner icon)
	difference with 'cylinder' object
	click Apply

Move spars out of the way, check holes were made
In mesh edit mode select all and press P to separate by loose parts
In object edit mode, do Alt+C for "curve from mesh"

In text editor, paste python script
Change output file and parameters as necessary
Right click and run script
Adjust positions of numerical labels, run again





Exporting script setup
----------------------

Command needed on Linux to install dxfwrite library (requires Blender restart?)
	python3 -m pip install dxfwrite


More info on dxfwrite library including API docs if you want to improve the script
	https://pypi.org/project/dxfwrite/
	https://dxfwrite.readthedocs.io/en/latest/





Parameters for the export script
--------------------------------

reverseOrder = False
Set to true to order from wingtips first

scale = 10
Eg. if the Blender units are cm and the QCAD file uses mm, scale would be 10

spacing1 = 200
The initial vertical distance between slices

spacing2 = 100
The subsequent vertical distance between slices

numSpacing1Slices = 3
How many slices to separate by spacing1 before switching to spacing2

startY = 0
The initial vertical position for the first slice

addLabels = True
Whether to add a numerical label to each slice

labelsX = 517
The horizontal position for labels (QCAD units)

labelsY = -47
The initial vertical position for labels (QCAD units)

Height of the label font
fontHeight = 8