The discussion on magic circle projection technology continued.
"If we draw it from scratch like Reiko did earlier, there's no issue at all, but..." Jin murmured.
Doing so for complex magic circles, however, would simply take far too long to render.
Jin wondered if he could adapt technology from Earth.
(Televisions were... what was it called again... raster graphics?)
He considered whether they could draw an image by scanning horizontal and vertical lines like a cathode-ray television, but quickly reconsidered.
(That doesn't seem very practical.)
To begin with, Jin wasn't particularly well-versed in that field of electronics.
"In that case, projecting the magic circle using a 'mold' seems like our best bet after all."
The plan was to settle on a general direction first, then figure out how to overcome any hurdles along the way.
"What about a reflective type?"
Among overhead projectors (OHPs), a few rare models used that method.
While they were prone to insufficient light output and poor color reproduction, they had the distinct advantage of allowing the direct use of handwritten manuscripts or photographs without needing to copy them onto transparent film.
Around the year 2000, when Jin was a student, they were still in use across schools and offices.
Nowadays, they had largely faded into obscurity thanks to modern digital projectors and massive display monitors.
Jin had seen a reflective unit once or twice in the past.
"If we draw it with silver lines on black paper, wouldn't it project clearly?" Jin suggested.
"I see. That would make it easy to produce the data—or rather, the 'mold,'" Eira agreed.
"Instead of paper... wouldn't a black slate work better as a base?" Groma added, noting that a stone slab would offer a flatter, more reliable surface for a mold.
"True. The projector will be built as a magi-device anyway, so that won't be an issue..."
"From this angle, it seems to have the advantages of being both easy to manufacture and low-cost," Kachea said, evaluating the concept from an economic standpoint.
"Which brings us back to the real bottleneck: the 'trigger'..."
Even Jin couldn't pull an immediate solution out of thin air.
Then Kachea spoke up.
"In short, we just need an incomplete magic circle that we finish only when we want to use it, right?"
"That's it!"
Kachea's words sparked a sudden flash of inspiration.
"We leave a piece missing from the trigger magic circle, and then fill it in right as we wake it up."
"Wouldn't that require two projectors, then?" Groma raised, pointing out an apparent flaw.
"No, that's not necessary. That's precisely why using a projector and a mold works in our favor."
Jin proposed creating a mold with a cutout or missing section, into which the missing piece could be slotted whenever needed.
"I get it! Simple, but effective." Eira nodded in approval.
"A manual operation feels a bit inconvenient, though..." Groma muttered, sounding slightly dissatisfied.
It seemed he had envisioned a fully automated system once the magi-device was turned on.
"In that case, we can just let a Golem arm handle the insertion," Jin replied pragmatically. His philosophy was always to build a working prototype first.
Then, an additional thought struck him.
"Wait, in that case, wouldn't a transmission type be better than a reflective one?"
With a transmission system, he figured they could complete the magic circle by layering slides over each other like animation cels.
It was an idea unique to someone steeped in anime culture like Jin.
"So we draw the magic circle on transparent glass and stack them... Could we perhaps stack magical effects as well?" Kachea asked with keen interest, but Jin shook his head.
"No, I doubt it'll go that smoothly. We'll have to experiment to know for sure, but magic circles likely have issues with compatibility. Spells that interfere with each other would probably just diminish in potency."
For instance, overlapping fire-attribute and water-attribute magic circles would likely cancel each other out rather than activate simultaneously.
"Couldn't we amplify the effect by layering fire-attribute magic, then?" Kachea pressed, reluctant to drop the idea.
"I have my doubts about that too," Eira chimed in, countering her. "It's the same problem as three-dimensional magic circles. The supply of free ether is limited, so that's going to be the bottleneck."
"Ah, good point..."
Seeing Kachea's disappointment, Jin offered some reassurance.
"Well, this is all just theoretical for now. Testing and confirming our hypotheses is what matters."
"Then we're settling on a transmission type after all?" Groma Tray asked. "Without enough light output, we won't be able to project very far anyway."
"Yeah, Groma's right about that."
After going back and forth, they ultimately decided to commit to the transmission-style method.
"In that case, will the magic circle be drawn in black lines?" Eira asked, assuming that would be the natural outcome of drawing on transparent glass.
"Wouldn't it be better to coat the glass in black and scratch the lines into it?"
"Oh, right! Smart thinking, Jin!"
It was the basic concept of positive and negative film, but Jin's ability to pivot so readily came from his familiarity with modern Earth technologies.
"So to summarize: we have a light projector, and by slotting the 'mold' into it, we project the magic circle, yes?"
"That's the gist of it."
Hearing Kachea—who was arguably the least familiar with such mechanics—summarize it cleanly gave Jin confidence that the concept was straightforward enough for anyone to grasp.
"Um, will it really project that clearly? Won't the image blur?"
"That's a very fair concern. We'll have to build prototypes and test various configurations."
Even standard slide projectors required adjusting the lens to bring the image into sharp focus.
"To address that, I'm wondering if a pinhole might do the trick."
Jin wanted to eliminate the need for focusing entirely to minimize time lag.
If an operator had to project the light and then manually adjust the focus, the added step would slow down deployment significantly.
While a pinhole had the drawback of producing a dimmer image, it possessed the distinct advantage of a deep depth of field, keeping things in focus naturally.
Covering a window with cardboard and poking a small hole through it would project an inverted image of the outside world into the room.
Back when Jin was a young boy at the Ruins, the Orphanage Director had demonstrated that very experiment to him. He remembered being utterly captivated and filled with wonder.
Incidentally, the setup went by the name camera obscura.
"That sounds fascinating!"
"Leave it to Jin to know such quirky tricks!"
"Jin-san, that's incredible!"
The moment he brought up the concept of a pinhole camera, Eira, Kachea, and Groma immediately latched on, leaving Jin explaining the optics of it while putting magic circle projection technology entirely on the back burner.