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It is playtime again! We have come up with something new: TRIme is the name of our second self-made video game console. TRIme is a malapropism of the English expression "Try me!". At the same time "TRI", which comes from Latin, stands for the number three. We use two semi-transparent mirrors and one impermeable mirror. With them we have built a device that creates a 3D-like visual impression by parallel projection of two or more images. So we can superimpose different contents for foreground, middle ground, and background in one line of sight for the viewer. The following picture shows how this is done:
The monitor is mounted horizontally. Two semi-transparent mirrors and a third mirror at an angle of 45 degree are mounted one behind the other. The third mirror is opaque. Each mirror reflects a third of the monitor image vertically. When developing a game, one could divide the monitor image into foreground, middle ground, and background. If you then look into TRIme from the front, these three areas are superimposed. Since this may not be so easy to understand, a photo of the open video game system follows:
We have reprogrammed a Breakout-like game, to get a feel for the unusual requirements that TRIme places on game developers. The game is not finished yet. This is what it looks like on TRIme:
What hardware did we use in TRIme? TRIme uses a Raspberry Pi 3 B+ as computer. This computer costs less than 40 EUR and is powerful enough for graphically not very complex 2D games which, for instance, can be programmed in Processing or Python. The following is an overview of the components of TRIme:
Single board computer Raspberry Pi 3 B+
Housing made of 5mm thick MDF, laser-cut
Cover plates made of 3mm thick MDF, laser-cut
10 Inch built-in HDMI monitor
2x semi-transparent mirrors
Audio amplifier board, audio via the jack output of the RPi, ground isolator
2x 8 Ohm speakers, two buttons for volume control
Sanwa digital joystick, four arcade buttons
Reset button for software reset
Slightly customized, current Linux Raspbian version Programming Language Processing, Version 3.5.3 for ARM
Due to its construction, TRIme has certain peculiarities which can be advantageous or disadvantageous for the game developer - depending on his/her point of view. A semi-transparent mirror has defined degrees of transmission and reflection. It reflects light, in our case mostly from the monitor. This feature is desirable because we want to see the monitor image in our line of sight. Furthermore, a semi-transparent mirror lets the light that falls on it from behind pass through proportionally. This is also good because we not only want to see the foreground, but also the middle and background.
Here comes the first sticking point: since each mirror does not let pass all the light falling from it, the brightness of the game scene decreases towards the back. So you do not perceive the contents on the mirrors as equally bright: a white area on the rear mirror appears to us rather as a medium grey. The second sticking point: since the mirrors are semi-transparent, colours lying on top of each other mix additively. If one superimposes a red, a green, and a blue splash on the three mirrors, one sees a cream white from the front. The third sticking point: the darker the color used, the more transparent it is.
Stupid? Not necessarily!
Due to the reflection of the monitor image into the vertical, the game seems to float somehow in space. That's cool!
The game graphics have something "holographic" about them. Of course mirroring has nothing to do with holography. Interested people please look up the term "Pepper's Ghost" at this point...
You can "hide" something behind a bright surface on the front pane, which is located on one of the rear panes. This is not possible on an ordinary monitor.
How about a game in which you have to arrange differently shaped blocks in rows or columns and you get bonus points if differently colored blocks add up to a certain color?
If you program a game that scrolls horizontally or vertically in three planes, you get something like "natural parallax scrolling", because the depth planes in TRIme are actually arranged in depth!
Games with vector graphics without filled areas look especially nice on TRIme if you use all three depth layers.
A construction with two or more than three mirrors is of course also conceivable. Have we aroused your interest in copying TRIme? That makes us happy! Here you will soon find the building instructions.