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How VR games trick you into thinking objects have weight

Gravity's Rainbow.

Immersion is easily virtual reality’s biggest strength over what you might call flat gaming. When done well, VR can whisk us away to familiar worlds, storybook fantasies, a galaxy far far away, even the mountainside for a quick spot of climbing. Putting players directly inside these 360 degree spaces, there’s an utter joy to the medium that can’t be recreated on a TV or PC monitor. Often, that hinges on intuitive use of motion controls - and in VR, hand movement is integral.

Some VR games support traditional controllers but, honestly, they’ve never done the format justice. Direct hand and finger tracking is promising yet limited, making motion controls an adaptable middle ground. While they can’t replicate our exact hand, grip and trigger buttons add significant physicality when holding objects. But this poses another problem. With games using the same controllers for object interaction, how do you convey object weights differently? Picking up items is one thing, throwing them accurately is another.

Following the release of several physics-based VR games like Boneworks, I was curious to learn more, so I spoke to two developers. The first is Immersion Games, the developers of Disc Ninja, where I spoke to CEO Bartosz Rosłoński. Presently, his team is working on a major update to Disc Ninja’s “flight and throwing model,” letting them expand the game’s arsenal of throwable objects. After that I spoke to Tunermaxx’s Kalle Max Hofmann, the game director for Rainbow Reactor: Fusion, an expanded version of Rainbow Reactor. Currently the team's developing Snow Scout, which utilises a “physics-based approach.”

Disc Ninja.Watch on YouTube

At face value, Disc Ninja and Fusion two very different games. Disc Ninja’s core premise revolves around a feudal Japanese version of disc golf, while Fusion sees us restoring power to Rain City’s powerplant, throwing paintballs onto a grid in a match-three puzzler. However, both share a gameplay commonality of throwing objects to achieve your goal. As such, I queried each team’s design philosophy, so I could better understand what's going on.

With Disc Ninja, Rosłoński confirmed Immersion followed “key objectives” rather than a set philosophy, focused on engaging and entertaining gameplay. Advising the “full body experience” requires extensive testing, they invited a professional Polish frisbee player to test disc-throwing games. “Unsurprisingly, not one of the titles tested felt quite like the real thing,” Rosłoński tells me. VR hardware continues improving, yet he believes current options “limit the sensory experience and interaction in both directions between the game and the player.“ Accordingly, Immersion aimed to balance “arcade-like ease of use and simulation.”

As for Fusion, Hoffman told me that 2019’s Boneworks ushered in, “a kind of new thinking [as to] how to represent the player's body in VR.” Telling me earlier games put your hands where controllers are, he stated, “this works best to give a feeling of connectedness” to VR and how that’s especially useful for newcomers. There are issues though. “Virtual objects cannot "stop" your hands when you move through them," he told me, "as there is no feedback in the real world that could hold them back.” So, a new approach formed where, “virtual hands obey physics and collisions as they would in the real world, or even in a traditional game.” However, that can lead to situations where virtual hands aren’t in the same place as your real hands.

Boneworks remains a gold standard for tactile VR.Watch on YouTube

As for object weight, Rosłoński cites the aforementioned hardware limitations. “Vibrations help with adding some ‘resistance’ to virtual objects” he said, but adds that they don’t feel that different from the controller would. Ultimately, he confirms these factors makes the visual element of handling objects crucial. You can free throw or lock-in your swing direction, he explains, saying that Immersion sought to provide “a more accessible way to learn, ease into the rhythm and enjoy the beautiful environments.” Telling me developers have many hidden tricks, Immersion chose a “more obvious way to simplify the throws,” still leaving distance and height for players to master.

As for Fusion, Hoffman elaborated on design philosophy, telling me that if we sync player hands with real hands, “there is absolutely no chance to create a feeling of weight in something that is weightless.” Much like Rosłoński, he confirmed you can only adjust this through vibration feedback. It’s a solution that’s seen wider adoption, as Sony is prominently supporting haptic feedback within PlayStation VR2. Microsoft aren’t as interested in wider VR gaming – Minecraft aside - though its researched uses for haptic controllers, previously showcasing a wrist-worn device called PIVOT.

With a physics-based approach, Hoffman confirmed such games can “show object weight in a visual way by showing how your hand is dragged downwards by the object, once you get a hold of it.” He calls this method interesting for experienced players, but warns this can be confusing for newer users. Regarding throwing paintballs, he admits it’s “very hard to accurately simulate the process of throwing objects in VR,” saying everyone has different depth perception due to things like our facial features.

Red Matter is great for a feeling of weightiness.Watch on YouTube

Finally, Hoffman detailed Fusion’s unique position as an expanded release, factoring in feedback. Being told the paintballs felt too heavy, Tunermaxx revamped them to become more weightless. The trade-off? Trajectories became harder to anticipate. As such, Hoffman recommends pushing paintballs forward, “like in a shot-putt motion” for the best results. Visually, hands become invisible once a tool is grabbed in Fusion, shifting its point of origin in relation to the player’s real hand. Evidently, balancing this is tricky, as Fusion was then criticised for paintballs lacking precision and feeling too light.

I won’t pretend there’s an easy solution here, and for VR to continue building upon its immersive promise, it’ll need addressing in future hardware. I doubt VR will ever truly be perfected – similarly I’d (perhaps controversially) claim the perfect console doesn’t exist. But as hardware evolves, I’m certain object handling will too. Until then, developers are making commendable efforts and, personally, I’m excited to see what’s next.

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