On the way to work today I remembered an old trick to create a "fire" effect: you randomly assign a colour to the pixels on the bottom row of the screen (in the same hue) and for each row above it take the average of the 3 pixels immediately below it, and 1 pixel that is two rows below it.
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The effect "smooths out" the colours as they move up the screen. If you make the colours start at white, then move through yellow, red, and black - then it looks all fire-y. But adding the array look-up just killed my browser, so I'm sticking with black & white and calling it "smoke". Pretty useless, but there you go.
I had originally done it with the
putImageData API calls - but decided to change it to drawing circles instead of pixels. This was horrrribly slow, so I moved on to filled rectangles. Also horrrribly slow, but passable.
Check the "smoke" effect (requires Canvas)