et4000.fractals
For the new generation, et4000 was a popular VGA video card from the early 90's (late 80's) with 512KB/1MB of onboard memory and resolution until 1024x768 with 256 colors (via LUT table)
This is a my old project ('90/'91), at the time of university, that uses low level programming (ASM) to access to video memory, and FPU 387 (32 bit floating point, math coprocessor: optional in the PCs of that time).
It can be built with Turbo C++ 2.0, or Borland C++ 3.x (anyway it's a C project for DOS), need also Turbo Assembler, present in both package. (Unfortunately I used a free, but "closed" library, as GUI. It's attached, but there are not sources: open source was not widespread.)
*To use in your personal VM is required also a VM with et4000 ROM emulator (like PCem / DosBox) if you want use resolution above the VGA/MCGA standard (320x200@256 colors)
I published it, mostly for the technique used to speed up the rendering, used also in Fractint, that calculate the boundary of areas with same exit values, and when the area is closed the algorithm fill it with color, without compute the singular internal pixel.
*You can switch between contour rendering and traditional rendering by SPACE key
It's extremely advantageous and spectacular to see with the internal "lake" of Mandelbrot. (the compute is "relatively slow", also to appreciate the render technique... and also because run in an emulator of 386/387 ;) ) Today, with current power of calculus and parallelism of CPU, and mostly GPU, there is no more necessity to use techniques like this... but in those days processing took minutes, not seconds, to complete to draw.
I have used em-DosBox, Emscripten port of DosBox, to make available a LIVE example via WebAssembly. Is required a web-browser with webAssembly capability: currently only FireFox and Chromium-based (Chrome, Opera, new MS Edge, etc) are supported.
LIVE ==> et4000.fractals Mandelbrot
| contour rendering | Mandel complete |
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LIVE ==> et4000.fractals JuliaCos
| contour rendering | JuliaCos complete |
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Currently I preferred "stretch" the DosBox screen to entire canvas (but it don't maintains the 1024x768 / 4:3 proportion)... In future I'll provide also a fixed un-stretchable canvas.
Can be explored also other fractal types: below the keys/buttons used inside the program.
Keys/MouseButtons used
F1/h/H Help (in the program is in Italian)
SPACE toggle regular renedeing / contour rendering (only in Mandel & Julia)
{1..8} interpolation # points (1=No interpolation, available in regular rendering)
F5 320x200x256 mode Vga & Mcga
F6 640x480x256 mode Tseng3000 or Tseng4000 mode
F7 800x600x256 mode Tseng3000 or Tseng4000 & Multi-sync mode
F8 1024x768x256 mode Tseng4000 1Mb & Multi-sync mode
Tab Parameters List
L Start change palette, any key rotate between present palettes.
Esc to select and return to fractal
S Save file (gif) ***doesn't not work in LIVE demo!***
F10 View current palette
Any key to return to fractal
Enter go to Zoom mode... after use:
- Mouse:
Right Button: resize box area
Left Button: starts calculating the selected area
Move NO buttons: move box area
- Keyboard :");
PgUp/PgDn: resize box area
+/- : tuning resizing step
Arrows : move box
C Change exploration parameters (may not work)
- Enter/Arrows: validate values
- Esc/CTRL-C : abort
- PgUp/PgDn : Confirm values and exit
+ Adds 8 to iterations number
- Subs 8 to iterations number
W Write actual parameter to file ***doesn't not work in LIVE demo!***
Esc Return to menu
*It was a personal program, never published, has just "a few" known bugs... from me ;)