In the last episode we learned how to code the rotozoom effect using floating point arithmetics. This however is pretty slow on ancient DOS machines, like 486 and even worse on slower machines. So in this episode we will rewrite the program to use integer based fixed point arithmetics.
Back in 1993 the Future Crew published „Second Reality“ on the PC. This was a mega-demo of epic proportions. It showcases many new and some old effects with a brilliant soundtrack. One of the effects that was very well done and that stuck in my mind was the „rotozoomer“. A tiling image being rotated and scaled in a very fluent animation. As a kid I wondered how it’s done. Later I learned the maths behind this and today we want to explore this simple yet brilliant effect. In this part we will deal with the basics and implement a floating point version. However the original code used fixed point integer arithmetics, which we will visit in a second video…
As 2020 comes to a close it’s time for another PowerBasic video. Last year we did a little snow simulation in PowerBasic around Christmas. This year we are going to do a fireworks simulation instead. And with a little sprinkle of x86 assembly language even!
One ubiquitous demo effect that can be seen on a wide variety of demos and intros is the twister or the twister bar. There are numerous examples in productions for the Amiga, Atari ST and 2600 that I know of (and even at least one on the Sega Master System). And probably a lot more that I don’t know. However I have never seen this effect in any of the old PC demos, except maybe in Future Crew’s PANIC, where something very similar was used for the vertical scrolling greetings. But it was not quite the same still. So today we will code a variant of the twister using Turbo C for MS DOS!
The SiliconLabs SI7021 is a very popular sensor for measuring temperature and humidity. It uses the I2C bus and is easily accessed from the ESP9266 or ESP32. Some breakout boards use different variants of the chip, namely the measurement Specialties HTU21D or even the Sensirion SHT21. These chips are more or less compatible to one another, but some don’t implement all the commands. However temperature and humidity can be used on all those chips. Today I’ll walk you through a tutorial of accessing the SI7021 via the Arduino Wire library.
It’s summer and it’s hot. And what better to code than another classic demo scene effect: the ubiquitous fire. But we will do it with a twist. The naive implementation is slow, very slow. Especially on older 286-486 computers. We will optimize the actual algorithm a bit and utilize a hidden VGA function that gives us scaling in the X-direction by a factor of 4 for free.
I got a question in the YouTube comments about the sine tables that we used for a few animations, like the Copper Bars, the Smooth Scrolling etc. In this episode I try to explain why and how to create sine tables. The idea is to speed up computations, since computing the sine or cosine — even with an FPU — takes an awfully long time on early MS DOS machines.
In the last live stream we did some Turbo C inline assembly, which was pretty fun. But let’s today use an actual pure assembler: the Borland Turbo Assembler. And let’s demystify some of the things surrounding assembly language. It is actually not that hard, so let’s write a hello world program, using assembly, for MS DOS!
Today we continue on our quest to make a small VGA game. So far we learned how to initialize Mode X and use some of its nice features. Copying images from system memory was painfully slow though. So let’s make it faster with a small trick!
The next part in the series about VGA Mode X programming. Let’s do some smooth scrolling. We already did that in text mode, but not in graphics mode, and not in a horizontal direction. So let’s lay down some basics!