I suppose I also ought to point out that you can vary the brightness of the electron beam by varying the voltage applied to the Z axis.
If you don’t require a solid line, you can use a timer to cause the electron beam to be switched on and off by switching the voltage on the Z axis.
Of course, time is everything when drawing vectors...
You can define the starting X and Y point of the integrators and the rate at which the integrators actually integrate (i.e. the X and Y slopes). Accurate timing from the point at which you permit the integrators to start ramping then defines where the endpoint of the vector is drawn to.
The other thing you need to be aware of is that the ‘character set’ is also drawn using vectors...
There is a maximum number of vectors that can be drawn in a given unit time before the human brain starts to perceive objectionable flicker, so this is the limit on the complexity of the games that can produced. This is increased if long persistence phosphors are used on the CRT - but this also limits the ‘dynamic’ content.
Theory over...
Fortunately, the Vectrex ROM contains routines to draw lists of vectors and characters themselves - so you are spared the complexity of the underlying vector generation hardware!
However, most of the software (if I remember correctly) is pretty much written in assembly code.
Have a read of this website:
https://www.playvectrex.com/designit/chrissalo/toc.htm.
I particularly like the online assembler at
https://www.asm80.com/. However, you will have to obtain a copy of the ROM entry points equates to be able to use it. Athens processor type required is 6809.
You should also consider how to actually develop the software. The Vectrex generally works with ROM cartridges, so you would have to burn an EPROM and test it. Then try and find out why it doesn’t work, erase the EPROM and start again... Repeat...
There is a Vectrex emulator that will allow you to develop and test your code on a PC and then burn an EPROM when you are convinced it works.
There are also development cartridges (containing either battery-backed RAM or FLASH) that can be used to speed up the develop and test cycle.
EDIT: The full programming manuals etc. are here:
https://www.playvectrex.com/designit_f.htm.
You might also be interested in this:
https://www.vectrex.biz/?
Dave