cube¶

spinning wireframe 3D cube (the stage-7 graphics demo)
NAME
    cube - spinning wireframe 3D cube (the stage-7 graphics demo)

SYNOPSIS
    cube [frames] [s]

DESCRIPTION
    Draws a perspective wireframe cube -- front face red, back face
    green, connecting edges blue (stage 9 colour-per-record) -- and
    spins it about two axes, one frame at a time, then exits. With no argument it runs 64
    frames (one full turn); a numeric argument runs that many. Needs the
    display; prints ?No display without one.

    The cube is the first client of the C 3D library (/lib/lib_g3d.c, used
    as `//#use gfx` + `//#use g3d` from C): a retained pool of 3D edges
    (g3line), a window on the view plane (g3window), a viewport on the
    screen (g3view), perspective projection (g3persp), and a render call
    (g3render) that clips, projects, maps and hands each surviving edge to
    the display's hardware LINE. The rotation itself is the demo's own
    integer sine table, not the library's.

    With the GL engine fitted (stage 10c) the cube is a STORED COMMAND
    LIST that spins itself: the list nudges the card's modeling matrix
    (MDROTY 6, MDROTX 3 per pass), erases, draws the 12 edges, flips
    and waits a frame tick -- and CLOOP runs it N times with the CPU
    completely idle. On the way in it CLEARS both framebuffer pages
    (power-on contents are undefined) and on the way out it rejoins
    them (PGSYNC), so drawing afterwards behaves. `cube N s` forces the
    stage-7 all-software path (~72 ms a frame, rebuilt from constants
    every frame so frame N is identical on every run) -- without a GL
    engine that path is the automatic fallback.

EXAMPLES
    cube            one full turn and exit
    cube 500        keep spinning for 500 frames

SEE ALSO
    g3d, gfx, basic (GRAPHICS section)