dragonruby-3d

DragonRuby is a 2D engine but supports several pseudo-3D and true 3D techniques.

Sprite-Based 3D (VR / Cube Style)

Build 3D objects from six 2D sprites with x/y/z positioning and angle_x/angle_y rotation:

def cube(x:, y:, z:, size:, sprite:)
  half = size / 2
  [
    { x: x,    y: y,    z: z,        w: size, h: size, **sprite },         # front
    { x: x,    y: y,    z: z + size, w: size, h: size, **sprite },         # back
    { x: x,    y: y + half, z: z + half, w: size, h: size, angle_x: 90, **sprite },  # top
    { x: x,    y: y - half, z: z + half, w: size, h: size, angle_x: 90, **sprite },  # bottom
    { x: x - half, y: y, z: z + half, w: size, h: size, angle_y: 90, **sprite },    # left
    { x: x + half, y: y, z: z + half, w: size, h: size, angle_y: 90, **sprite }     # right
  ]
end