Saturday, September 12, 2020

Ryo Goes to the Moon | Shenmue II Out of Bounds Hack

Ryo Goes to the Moon | Shenmue II Hack

One of the many small coding details of Shenmue that surprised even the fans is that the moon that can be seen in a number of iconic Shenmue II scenes is in fact a proper three-dimensional object, and not just a simple two-dimensional image.

This was something that software house d3t discovered when they worked on the Shenmue I & II re-release:

PC Gamer: Did you find anything interesting in the source code?

Noel Austin (d3t): The moon in Shenmue 2 is not a texture. It’s an actual 3D object in the distance correctly lit by the sun direction. This produces accurate phases. We were surprised by this level of detail!

With the help of a hack tool we took Ryo out of bounds on a solo flight to the moon, and he was able to see for himself that Noel's assertion was indeed the truth!

  • Scroll to the end of this post to watch the video footage.
The moon over Man Mo temple.

Our investigation starts with Ryo in Wise Man's Quarter. The weather is cloudy, which blocks any view of the stars or moon, since the cloud effects in Shenmue 2 are created using a dome-shaped sky box with moving cloud textures overlaid on it.

Once Ryo has passed through the cloud layer, the moon and a background of stars are revealed, and we can see that these exist even when hidden from the player.

Using the tool again, we can swiftly move Ryo closer.

The stars are drawn on as a texture on a second sky box which sits a little further out than the moon's position. One side of the moon is illuminated, and as Ryo moves around it, the effect is that the moon's phase changes convincingly.

Seen close up, we can get an idea of its actual size compared to other objects in the game: as a rough estimate, the actual height of the moon is equivalent to around thirty Ryos stacked on each other's shoulders.

With Ryo standing (floating?) still, we can also see that the moon is in a constant, steady motion - it is actually moving through the sky throughout the game, at a speed roughly equivalent to Ryo's jogging speed.

This level of simulation is quite amazing, especially in a game from twenty years ago.

Watch the full video footage of Ryo traveling into space and visiting the moon, below.


Image Credit:

Thank you to SkillJim for the awesome title image. Check out SkillJim's YouTube channel here for a trove of fun Shenmue content!


How Sega brought Shenmue back to life on PC (PC Gamer, Sep 2018)

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