Fully documented source code for Elite on the BBC Micro

Re:Fully documented source code for Elite on the BBC Micro by jacquesm on Monday September 28, 2020 @04:31AM (#24614340)

> Pixel-smooth vertical scrolling by poking the CRTC on timed interrupts to modify the character height dynamically, so as to squash a row at the top and expand a row at the bottom to shift the image with pixel precision (contradicting the received wisdom that the CRTC could only scroll character cells).

How frustrating that even today that is very hard for quite a few environments. I am working on something that requires a very smooth horizontal scroll of a large canvas in the browser. So far jagged edges are my lot, most tricks only work in a small subset of the cases.

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Re:Fully documented source code for Elite on the BBC Micro by jlokier on Monday September 28, 2020 @05:28AM (#24614720)

Ah, browsers. Vsync timing is basically impossible to guarantee with them. It's dependent on which browser, browser version, which OS, and I suspect even which graphics card and driver (because OpenGL is affected by those).

I use this to asses:

https://www.vsynctester.com/

but this doesn't give me a feeling that all browsers in common use will do "buttery smooth" any time soon:

https://www.vsynctester.com/firefoxisbroken.html

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Re:Fully documented source code for Elite on the BBC Micro by jacquesm on Monday September 28, 2020 @06:53AM (#24615272)

Thank you for that, I wasn't aware that site existed, already confirmed some of my worst suspicions. What we are working on is a music application that horizontally scrolls a score drawn on a canvas. Smooth scrolling is quite essential to be able to keep to the beat (see: https://news.ycombinator.com/item?id=24615125)

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