<?xml version="1.0" encoding="ISO-8859-1"?>

<screensaver name="projectiveplane" _label="Projective Plane" gl="yes">

  <command arg="--root"/>

  <video href="https://www.youtube.com/watch?v=Zg6ONPUTwUQ"/>

  <hgroup>
    <select id="display-mode">
      <option id="random"      _label="Random surface"/>
      <option id="wire"        _label="Wireframe mesh"      arg-set="--mode wireframe"/>
      <option id="surface"     _label="Solid surface"       arg-set="--mode surface"/>
      <option id="transparent" _label="Transparent surface" arg-set="--mode transparent"/>
    </select>

    <select id="appearance">
      <option id="random" _label="Random pattern"/>
      <option id="solid"  _label="Solid object"    arg-set="--appearance solid"/>
      <option id="bands"  _label="Distance bands"  arg-set="--appearance distance-bands"/>
      <option id="bands"  _label="Direction bands" arg-set="--appearance direction-bands"/>
    </select>

    <select id="colors">
      <option id="random"   _label="Random coloration"/>
      <option id="twosided" _label="One-sided"        arg-set="--colors one-sided"/>
      <option id="twosided" _label="Two-sided"        arg-set="--colors two-sided"/>
      <option id="rainbow"  _label="Distance colors"  arg-set="--colors distance"/>
      <option id="rainbow"  _label="Direction colors" arg-set="--colors direction"/>
      <option id="depth"    _label="4d depth colors"  arg-set="--colors depth"/>
    </select>

    <boolean id="change-colors" _label="Change colors"
              arg-set="--change-colors"/>

    <select id="projection3d">
      <option id="random"          _label="Random 3D"/>
      <option id="perspective-3d"  _label="Perspective 3D"  arg-set="--projection-3d perspective"/>
      <option id="orthographic-3d" _label="Orthographic 3D" arg-set="--projection-3d orthographic"/>
    </select>

    <select id="projection4d">
      <option id="random"          _label="Random 4D"/>
      <option id="perspective-4d"  _label="Perspective 4D"  arg-set="--projection-4d perspective"/>
      <option id="orthographic-4d" _label="Orthographic 4D" arg-set="--projection-4d orthographic"/>
    </select>
  </hgroup>

  <hgroup>
    <vgroup>
     <hgroup>
      <number id="speed-wx" type="slider" arg="--speed-wx %"
              _label="WX speed"
              _low-label="-4" _high-label="4"
              low="-4.0" high="4.0" default="1.1"/>
     </hgroup>

     <hgroup>
      <number id="speed-wy" type="slider" arg="--speed-wy %"
              _label="WY speed"
              _low-label="-4" _high-label="4"
              low="-4.0" high="4.0" default="1.3"/>
     </hgroup>

     <hgroup>
      <number id="speed-wz" type="slider" arg="--speed-wz %"
              _label="WZ speed"
              _low-label="-4" _high-label="4"
              low="-4.0" high="4.0" default="1.5"/>
     </hgroup>
    </vgroup>

    <vgroup>
     <hgroup>
      <number id="speed-xy" type="slider" arg="--speed-xy %"
              _label="XY speed"
              _low-label="-4" _high-label="4"
              low="-4.0" high="4.0" default="1.7"/>
     </hgroup>

     <hgroup>
      <number id="speed-xz" type="slider" arg="--speed-xz %"
              _label="XZ speed"
              _low-label="-4" _high-label="4"
              low="-4.0" high="4.0" default="1.9"/>
     </hgroup>

     <hgroup>
      <number id="speed-yz" type="slider" arg="--speed-yz %"
              _label="YZ speed"
              _low-label="-4" _high-label="4"
              low="-4.0" high="4.0" default="2.1"/>
     </hgroup>
    </vgroup>

    <vgroup>
     <hgroup>
     <number id="walk-direction" type="slider" arg="--walk-direction %"
             _label="Walk dir     "
             _low-label="-180" _high-label="180"
             low="-180.0" high="180.0" default="83.0"/>
     </hgroup>

     <hgroup>
     <number id="walk-speed" type="slider" arg="--walk-speed %"
             _label="Walk speed"
             _low-label="1" _high-label="100"
             low="1.0" high="100.0" default="20.0"/>
     </hgroup>

     <hgroup>
     <number id="delay" type="slider" arg="--delay %"
             _label="Frame rate" _low-label="Low" _high-label="High"
             low="0" high="100000" default="25000"
             convert="invert"/>
     </hgroup>
    </vgroup>
  </hgroup>

  <hgroup>
    <select id="view-mode">
      <option id="walk"      _label="Random motion"/>
      <option id="walk"      _label="Walk"          arg-set="--view-mode walk"/>
      <option id="turn"      _label="Turn"          arg-set="--view-mode turn"/>
      <option id="walk-turn" _label="Walk and turn" arg-set="--view-mode walk-turn"/>
    </select>

    <boolean id="orientation-marks" _label="Show orientation marks"
              arg-set="--orientation-marks"/>

    <boolean id="showfps" _label="Show frame rate" arg-set="--fps"/>

    <xscreensaver-updater />
  </hgroup>



  <_description>
A 4D embedding of the real projective plane.

You can walk on the surface of the real projective plane or rotate it
in 4D or walk on it while it rotates in 4D.  Inspired by Thomas
Banchoff's book "Beyond the Third Dimension: Geometry, Computer
Graphics, and Higher Dimensions", Scientific American Library, 1990.

https://en.wikipedia.org/wiki/Real_projective_plane
https://en.wikipedia.org/wiki/Roman_surface
https://en.wikipedia.org/wiki/Cross_cap
https://en.wikipedia.org/wiki/Moebius_strip
https://mathworld.wolfram.com/RealProjectivePlane.html
https://mathworld.wolfram.com/RomanSurface.html
https://mathworld.wolfram.com/Cross-Cap.html
https://mathworld.wolfram.com/MoebiusStrip.html

Written by Carsten Steger; 2014.
  </_description>
</screensaver>
