This was another part for my planned Megademo. It incorporates four different effects. First of all there are the jumping characters of the scrolltext. I had created several different waves for the characters, with a range from a gentle wave to a almost chaotic chaos of opposing characters.
Jumping Text demo
The second effect is a mirror effect that copied screen lines from the scroll text field to a water-like surface. The space between two consecutive lines that were copied to the blue area of the screen was increasing, so that a simple sort (without horizontal compression) of central perspective view was established. When the characters touch the border to the blue area it almost looks like they dip into the water for a second, before they start their climbing motion.
The third effect I put into this demo was the Odiesoft logo drawer. I've seen similar effects in Amiga and Archimedes demos and thought that it would also look nice on an Amstrad. The Odiesoft logo was divided into several rectangles. I defined a number of forms in which order these rectangles were supposed to perform a certain action. The forms were for example a clockwize activation of all the rectangles, a saw-tooth form and some others.
The action that had to be performed for each rectangle was to gradually display or erase the current rectangle by painting for example a growing or shrinking circle that painted or removed the rectangle. Other forms were a rotating square and a water dribbling effect. On an Archimedes version I've seen they also had real 3D texture effects in the way that the rectangles rotated around the X axis and such, but I didn't even bother to try to do this on the Amstrad CPC. My demo was running already at 25 frames a second and I didn't wanted it to get even slower...
Slightly chaotic jumping text...
The last effect that is unvisible to most are the stars in the background. The crux about this was that I had just learned about the algorithm to connect any two points on a computer screen. These algorithm is usually used to paint lines, but it can also be used to compute the direct route from one point on the screen to another point as means for the animation of a pixel that represents for example a star.
I was pretty much proud on that especial piece of software. I not only made the stars become faster the "closer" they got in that fake 3d starfield simulation, I've also added color so that the stars in the "background" were darker than the ones closest to the viewer.
All in all I was very much satisfied with that demo, even though it ran with just 25 frames a second. Later I had to discover that on some screens you could see the remains of the characters hang out in the open on the right border of the screen. This was due to the fact that the characters weren't really removed from the screen when they exited it on the left side. I just scrolled them out of the visible area and thought nobody would realize that. But I didn't take the different CRTCs and their slightly different display characteristics into account...
As with all the other parts for this Megademo this part was never officially released. I used it one or two times to send "letters" to friends of mine. That is I typed the letter as scroll text message and the recipient had to run the demo to read the letter - this was surely a bothersome routine, but at that time I thought that this was cool...
... and very chaotic jumping text!
Anyway, likewise the other unreleased parts of my Megademo this part was also hidden in one of the Divine Demo parts of mine. This one was hidden in the "Shadows Demo". You had to press the keys "J", "U", "M" and "P" at the same time during the demo to get to this part.