Editing Appendix/Ramblings/VirtualReality (section)

==Clock==

On 23 September 2019 I found, and downloaded from GitHub, a useful COLLADA file &#8212; [https://github.com/chinedufn/collada-dae-parser/tree/master/test/fixture animated-blender-cube.dae], developed by user "chinedufn" &#8212; that performs a simple animation of a cube.  I successfully replaced the single, grey cube in chinedufn's model with my multi-colored "[[#Cube_Trio_by_a_Blender_Developer|cube trio]]" then, calling upon the skills that I had acquired by playing with the ''[[#AstroBoyWalk|astro_boy]]'' model, I used this modified animated-cube file to get more comfortable with COLLADA's animation instructions.  With this improved understanding, I started from scratch and built a model of a clock entirely within the COLLADA language.  This executable .dae file is presented immediately below as '''Example #8'''.  This model works wonderfully when displayed by my Mac's Preview app.

<table border="0" align="center" width="80%">
<tr><th align="center" colspan="2">Example #8 &#8212; Our Constructed Model of a Clock</th></tr>
<tr><td align="left">
<div style="height: 400px; width: 700px; overflow: scroll;">
<pre>
<?xml version="1.0" encoding="utf-8"?>
<COLLADA xmlns="http://www.collada.org/2005/11/COLLADASchema" version="1.4.1">
<!--
On 23 September 2019 I copied the following cube-animation file from github:
https://github.com/chinedufn/collada-dae-parser/blob/master/test/fixture/animated-blender-cube.dae
I have made substantial modifications in order to better understand how the animation instructions
actually work.

THIS FILE NAME:  Dropbox/3Dviewers/Clock/Arrow07.PERFECT.dae
It uses "polylist" and correct implementation of "normals" for all polygons of the Clock.
It also displays **two** clocks:  [Initially, we made one spin and the other not.]
It also adds a red "minute hand" to the clock; now, this is the only segment that spins.
-->
  <asset>
    <contributor>
      <author>jet53man</author>
      <authoring_tool>Raw XML</authoring_tool>
    </contributor>
    <created>2019-09-24</created>
    <modified>2019-09-29</modified>
    <unit name="meter" meter="1"/>
    <up_axis>Z_UP</up_axis>
  </asset>
  <library_images/>
    <library_effects>
        <effect id="ID5">
            <profile_COMMON>
                <technique sid="COMMON">
                    <lambert>
                        <diffuse>
                            <color>0 0 1 1</color>
                        </diffuse>
                    </lambert>
                </technique>
            </profile_COMMON>
        </effect>
        <effect id="InnerID5">
            <profile_COMMON>
                <technique sid="COMMON">
                    <lambert>
                        <diffuse>
                            <color>0.4 0.0 0.7 0.4</color>
                        </diffuse>
                    </lambert>
                </technique>
            </profile_COMMON>
        </effect>
        <effect id="ArrowID5">
            <profile_COMMON>
                <technique sid="COMMON">
                    <lambert>
                        <diffuse>
                            <color>1.0 0.0 0.0 1.0</color>
                        </diffuse>
                    </lambert>
                </technique>
            </profile_COMMON>
        </effect>
    </library_effects>
    <library_materials>
        <material id="ID6" name="material">
            <instance_effect url="#ID5" />
        </material>
        <material id="InnerID6" name="Inner_material">
            <instance_effect url="#InnerID5" />
        </material>
        <material id="ArrowID6" name="Arrow_material">
            <instance_effect url="#ArrowID5" />
        </material>
    </library_materials>
    <library_nodes>
        <node id="ID3" name="cube_component">
            <instance_geometry url="#Clock_OuterEdge">
                <bind_material>
                    <technique_common>
                        <instance_material symbol="Material2" target="#ID6">
                            <bind_vertex_input semantic="UVSET0" input_semantic="TEXCOORD" input_set="0" />
                        </instance_material>
                    </technique_common>
                </bind_material>
            </instance_geometry>
            <instance_geometry url="#Clock_InnerEdge">
                <bind_material>
                    <technique_common>
                        <instance_material symbol="Material2" target="#InnerID6">
                            <bind_vertex_input semantic="UVSET0" input_semantic="TEXCOORD" input_set="0" />
                        </instance_material>
                    </technique_common>
                </bind_material>
            </instance_geometry>
        </node>
        <node id="ArrowID3" name="cube_component">
            <instance_geometry url="#Clock_ArrowEdge">
                <bind_material>
                    <technique_common>
                        <instance_material symbol="Material2" target="#ArrowID6">
                            <bind_vertex_input semantic="UVSET0" input_semantic="TEXCOORD" input_set="0" />
                        </instance_material>
                    </technique_common>
                </bind_material>
            </instance_geometry>
        </node>
    </library_nodes>
    <library_geometries>
        <geometry id="Clock_OuterEdge">
            <mesh>
<!--
            **********************************************
            *
            *  Insert first portion of clock's structure
            *
            **********************************************
-->
                <source id="Clock_Positions">
                  <float_array id="Coordinates01" count="123"> 0.0  1.0  0.2 1.0  1.0  0.2 1.0  0.0  0.2 1.0 -1.0  0.2 0.0 -1.0  0.2 -1.0 -1.0  0.2 -1.0  0.0  0.2 -1.0  1.0  0.2 0.0  1.0 -0.2 1.0  1.0 -0.2 1.0  0.0 -0.2 1.0 -1.0 -0.2 0.0 -1.0 -0.2 -1.0 -1.0 -0.2 -1.0  0.0 -0.2 -1.0  1.0 -0.2 0.9  0.0  0.2 0.779423 0.45 0.2 0.45 0.779423 0.2 0.0  0.9  0.2 -0.45 0.779423 0.2 -0.779423 0.45 0.2 -0.9 0.0 0.2 -0.779423 -0.45 0.2 -0.45 -0.779423 0.2 0.0 -0.9 0.2 0.45 -0.779423 0.2 0.779423 -0.45 0.2 -0.9  0.0  -0.2 -0.779423 0.45 -0.2 -0.45 0.779423 -0.2 -0.0  0.9  -0.2 0.45 0.779423 -0.2 0.779423 0.45 -0.2 0.9 0.0 -0.2 0.779423 -0.45 -0.2 0.45 -0.779423 -0.2 -0.0 -0.9 -0.2 -0.45 -0.779423 -0.2 -0.779423 -0.45 -0.2  0.0 0.0 -0.2</float_array>
                  <technique_common>
                    <accessor source="#Coordinates01" count="41" stride="3">
                            <param name="X" type="float" />
                            <param name="Y" type="float" />
                            <param name="Z" type="float" />
                    </accessor>
                  </technique_common>
                </source>
                <source id="Clock_Normals">
                  <float_array id="InnerNormals01" count="18">
 1.0  0.0  0.0
-1.0  0.0  0.0
 0.0  1.0  0.0
 0.0 -1.0  0.0
 0.0  0.0  1.0
 0.0  0.0 -1.0
                  </float_array>
                    <technique_common>
                        <accessor source="#Normals01" count="6" stride="3">
                            <param name="X" type="float" />
                            <param name="Y" type="float" />
                            <param name="Z" type="float" />
                        </accessor>
                    </technique_common>
                </source>
                <vertices id="Clock_Vertices">
                    <input semantic="POSITION" source="#Clock_Positions" />
                </vertices>
                <polylist count="56" material="Material2">
                    <input semantic="VERTEX" source="#Clock_Vertices" offset="0" />
                    <input semantic="NORMAL" source="#Clock_Normals" offset="1" />
<vcount> 3 3 3 3 3  3 3 3 3 3  3 3 3 3 3  3 3 3 3 3  3 3 3 3 3  3 3 3 3 3  3 3 3 3 3  3 3 3 3 3  3 3 3 3 3  3 3 3 3 3  3 3 3 3 3  3</vcount>
<p> 0 2 1 2 8 2  1 2 9 2 8 2  7 2 0 2 15 2  0 2 8 2 15 2 1 0 2 0 9 0  2 0 10 0 9 0  2 0 3 0 10 0  3 0 11 0 10 0 3 3 4 3 11 3  4 3 12 3 11 3  4 3 5 3 12 3  5 3 13 3 12 3 5 1 6 1 13 1  6 1 14 1 13 1  6 1 7 1 14 1  7 1 15 1 14 1 2 4 17 4 16 4  2 4 1 4 17 4  1 4 18 4 17 4  1 4 0 4 18 4  0 4 19 4 18 4 0 4 20 4 19 4  0 4 7 4 20 4  7 4 21 4 20 4  7 4 6 4 21 4  6 4 22 4 21 4 6 4 23 4 22 4  6 4 5 4 23 4  5 4 24 4 23 4  5 4 4 4 24 4  4 4 25 4 24 4 4 4 26 4 25 4  4 4 3 4 26 4  3 4 27 4 26 4  3 4 2 4 27 4  2 4 16 4 27 4 14 5 29 5 28 5  14 5 15 5 29 5  15 5 30 5 29 5  15 5 8 5 30 5  8 5 31 5 30 5 8 5 32 5 31 5  8 5 9 5 32 5  9 5 33 5 32 5  9 5 10 5 33 5  10 5 34 5 33 5 10 5 35 5 34 5  10 5 11 5 35 5  11 5 36 5 35 5  11 5 12 5 36 5  12 5 37 5 36 5 12 5 38 5 37 5  12 5 13 5 38 5  13 5 39 5 38 5  13 5 14 5 39 5  14 5 28 5 39 5 </p>
                </polylist>
            </mesh>
        </geometry>
        <geometry id="Clock_InnerEdge">
            <mesh>
<!--
            **********************************************
            *
            *  Insert second portion of clock's structure
            *
            **********************************************
-->
                <source id="Clock_InnerPositions">
                  <float_array id="InnerCoordinates01" count="123">
0.0  1.0  0.2 1.0  1.0  0.2 1.0  0.0  0.2 1.0 -1.0  0.2 0.0 -1.0  0.2 -1.0 -1.0  0.2 -1.0  0.0  0.2 -1.0  1.0  0.2 0.0  1.0 -0.2 1.0  1.0 -0.2 1.0  0.0 -0.2 1.0 -1.0 -0.2 0.0 -1.0 -0.2 -1.0 -1.0 -0.2 -1.0  0.0 -0.2 -1.0  1.0 -0.2 0.9  0.0  0.2 0.779423 0.45 0.2 0.45 0.779423 0.2 0.0  0.9  0.2 -0.45 0.779423 0.2 -0.779423 0.45 0.2 -0.9 0.0 0.2 -0.779423 -0.45 0.2 -0.45 -0.779423 0.2 0.0 -0.9 0.2 0.45 -0.779423 0.2 0.779423 -0.45 0.2 -0.9  0.0  -0.2 -0.779423 0.45 -0.2 -0.45 0.779423 -0.2 -0.0  0.9  -0.2 0.45 0.779423 -0.2 0.779423 0.45 -0.2 0.9 0.0 -0.2 0.779423 -0.45 -0.2 0.45 -0.779423 -0.2 -0.0 -0.9 -0.2 -0.45 -0.779423 -0.2 -0.779423 -0.45 -0.2  0.0 0.0 -0.2</float_array>
                  <technique_common>
                    <accessor source="#InnerCoordinates01" count="41" stride="3">
                            <param name="X" type="float" />
                            <param name="Y" type="float" />
                            <param name="Z" type="float" />
                    </accessor>
                  </technique_common>
                </source>
                <source id="Clock_InnerNormals">
                  <float_array id="InnerNormals01" count="54">
 1.0  0.0  0.0
-1.0  0.0  0.0
 0.0  1.0  0.0
 0.0 -1.0  0.0
 0.0  0.0  1.0
 0.0  0.0 -1.0
 -0.965926 -0.258819 0.0
 -0.707107 -0.707107 0.0
 -0.258819 -0.965926 0.0
  0.258819 -0.965926 0.0
  0.707107 -0.707107 0.0
  0.965926 -0.258819 0.0
  0.965926  0.258819 0.0
  0.707107  0.707107 0.0
  0.258819  0.965926 0.0
 -0.258819  0.965926 0.0
 -0.707107  0.707107 0.0
 -0.965926  0.258819 0.0
                  </float_array>
                    <technique_common>
                        <accessor source="#InnerNormals01" count="18" stride="3">
                            <param name="X" type="float" />
                            <param name="Y" type="float" />
                            <param name="Z" type="float" />
                        </accessor>
                    </technique_common>
                </source>
                <vertices id="Clock_InnerVertices">
                    <input semantic="POSITION" source="#Clock_InnerPositions" />
                </vertices>
                <polylist count="24" material="Material2">
                    <input semantic="VERTEX" source="#Clock_InnerVertices" offset="0" />
                    <input semantic="NORMAL" source="#Clock_InnerNormals" offset="1"/>
<vcount>4 4 4 4  4 4 4 4  4 4 4 4  3 3 3 3  3 3 3 3  3 3 3 3</vcount>
<p> 16 6 17 6 33 6 34 6 17 7 18 7 32 7 33 7 18 8 19 8 31 8 32 8 19 9 20 9 30 9 31 9 20 10 21 10 29 10 30 10 21 11 22 11 28 11 29 11 22 12 23 12 39 12 28 12 23 13 24 13 38 13 39 13 24 14 25 14 37 14 38 14 25 15 26 15 36 15 37 15 26 16 27 16 35 16 36 16 27 17 16 17 34 17 35 17 28 5 29 5 40 5 29 5 30 5 40 5 30 5 31 5 40 5 31 5 32 5 40 5 32 5 33 5 40 5 33 5 34 5 40 5 34 5 35 5 40 5 35 5 36 5 40 5 36 5 37 5 40 5 37 5 38 5 40 5 38 5 39 5 40 5 39 5 28 5 40 5 </p>
              </polylist>
            </mesh>
        </geometry>
        <geometry id="Clock_ArrowEdge">
            <mesh>
<!--
            **********************************************
            *
            *  Insert arrow portion of clock's structure
            *
            **********************************************
-->
                <source id="Clock_ArrowPositions">
                  <float_array id="ArrowCoordinates01" count="30"> 0.0  0.85 0.25 0.1  0.0 0.25 0.0 -0.2 0.25 -0.1  0.0 0.25 0.0  0.85 0.05 0.1  0.0 0.05 0.0 -0.2 0.05 -0.1  0.0 0.05 0.0  0.0 0.25 0.0  0.0 0.05 </float_array>
                  <technique_common>
                    <accessor source="#ArrowCoordinates01" count="10" stride="3">
                            <param name="X" type="float" />
                            <param name="Y" type="float" />
                            <param name="Z" type="float" />
                    </accessor>
                  </technique_common>
                </source>
                <source id="Clock_ArrowNormals">
                  <float_array id="ArrowNormals01" count="18">
 0  0  1
 0  0 -1
 0.993151  0.116841 0.0
 0.447214 -0.894427 0.0
-0.447214 -0.894427 0.0
-0.993151  0.116841 0.0
                  </float_array>
                    <technique_common>
                        <accessor source="#ArrowNormals01" count="6" stride="3">
                            <param name="X" type="float" />
                            <param name="Y" type="float" />
                            <param name="Z" type="float" />
                        </accessor>
                    </technique_common>
                </source>
                <vertices id="Clock_ArrowVertices">
                    <input semantic="POSITION" source="#Clock_ArrowPositions" />
                </vertices>
                <polylist count="12" material="Material2">
                    <input semantic="VERTEX" source="#Clock_ArrowVertices" offset="0" />
                    <input semantic="NORMAL" source="#Clock_ArrowNormals" offset="1"/>
<vcount>3 3 3 3 3 3 3 3 4 4 4 4</vcount>
<p> 0 0 8 0 1 0 1 0 8 0 2 0 2 0 8 0 3 0 3 0 8 0 0 0 4 1 5 1 9 1 5 1 6 1 9 1 6 1 7 1 9 1 7 1 4 1 9 1 0 2 1 2 5 2 4 2 1 3 2 3 6 3 5 3 2 4 3 4 7 4 6 4 3 5 0 5 4 5 7 5 </p>
              </polylist>
            </mesh>
        </geometry>
    </library_geometries>
  <library_animations>
    <animation id="Cube_rotation_euler_Z">
      <source id="Cube_rotation_euler_Z-input">
<!--        <float_array id="Cube_rotation_euler_Z-input-array" count="5">0 0.2083333 0.4166666 0.625 0.8333333</float_array> -->
<!--        <float_array id="Cube_rotation_euler_Z-input-array" count="5">0 0.4167 0.8333 1.25 1.666</float_array> -->
        <float_array id="Cube_rotation_euler_Z-input-array" count="17">0 0.25 0.5 0.75 1.0 1.25 1.5 1.75 2.0 2.25 2.5 2.75 3.0 3.25 3.5 3.75 4.0</float_array>
        <technique_common>
          <accessor source="#Cube_rotation_euler_Z-input-array" count="5" stride="1">
            <param name="TIME" type="float"/>
          </accessor>
        </technique_common>
      </source>
      <source id="Cube_rotation_euler_Z-output">
<!--        <float_array id="Cube_rotation_euler_Z-output-array" count="5">0 -22.5 -45 -67.5 -90</float_array> -->
        <float_array id="Cube_rotation_euler_Z-output-array" count="17">0 -22.5 -45 -67.5 -90 -112.5 -135.0 -157.5 -180.0 -202.5 -225.0 -247.5 -270.0 -292.5 -315.0 -337.5 -360.0</float_array>
        <technique_common>
          <accessor source="#Cube_rotation_euler_Z-output-array" count="5" stride="1">
            <param name="ANGLE" type="float"/>
          </accessor>
        </technique_common>
      </source>
      <sampler id="Cube_rotation_euler_Z-sampler">
        <input semantic="INPUT" source="#Cube_rotation_euler_Z-input"/>
        <input semantic="OUTPUT" source="#Cube_rotation_euler_Z-output"/>
      </sampler>
      <channel source="#Cube_rotation_euler_Z-sampler" target="jetman/rotationZ.ANGLE"/>
    </animation>
    <animation id="Cube_scale_Z">
      <source id="Cube_scale_Z-input">
<!--        <float_array id="Cube_scale_Z-input-array" count="5">0 0.2083333 0.4166666 0.625 0.8333333</float_array>  -->
        <float_array id="Cube_scale_Z-input-array" count="5">0 0.0694 0.1389 0.2083 0.2778</float_array>
        <technique_common>
          <accessor source="#Cube_scale_Z-input-array" count="5" stride="1">
            <param name="TIME" type="float"/>
          </accessor>
        </technique_common>
      </source>
      <source id="Cube_scale_Z-output">
<!--    <float_array id="Cube_scale_Z-output-array" count="5">0.5 0.4 0.3 0.2 0.1</float_array>  -->
        <float_array id="Cube_scale_Z-output-array" count="5">1.0 1.0 1.0 1.0 1.0</float_array>
        <technique_common>
          <accessor source="#Cube_scale_Z-output-array" count="5" stride="1">
            <param name="Z" type="float"/>
          </accessor>
        </technique_common>
      </source>
      <sampler id="Cube_scale_Z-sampler">
        <input semantic="INPUT" source="#Cube_scale_Z-input"/>
        <input semantic="OUTPUT" source="#Cube_scale_Z-output"/>
      </sampler>
      <channel source="#Cube_scale_Z-sampler" target="jetman/scale.Z"/>
    </animation>
  </library_animations>
    <library_controllers/>
    <library_visual_scenes>
        <visual_scene id="EntireLayout">
<!--
***********
*
* Evidently, it is important for the "id" of this node to be shared
* with the "directory" name that is used in the animation "channel"
* instructions.  For example, "jetman" is used here.
*
***********
-->
          <node id="TwoClocks">
            <node id="firstclock" name="instance_1">
              <translate>0.0 1.0 0.0</translate>
              <rotate sid="rotationX">1 0 0 90</rotate>
              <rotate sid="rotationZ">0 0 1 0</rotate>
<!--
              <rotate sid="rotationY">0 1 0 90</rotate>
-->
              <scale sid="scale">1 1 1</scale>
              <instance_node url="#ID3" />
            </node>
            <node id="jetman" name="instance_Arrow">
              <translate>0.0 1.0 0.0</translate>
              <rotate sid="rotationX">1 0 0 90</rotate>
              <rotate sid="rotationZ">0 0 1 0</rotate>
<!--
              <rotate sid="rotationY">0 1 0 90</rotate>
-->
              <scale sid="scale">1 1 1</scale>
              <instance_node url="#ArrowID3" />
            </node>
            <extra>
              <technique profile="FCOLLADA">
                <start_time>0</start_time>
                <end_time>4.0</end_time>
              </technique>
            </extra>
            <node id="secondClock" name="instance_2">
              <translate>10.0 0.0 0.0</translate>
<!--
              <rotate sid="rotationZ">0 0 1 90</rotate>
-->
              <rotate sid="rotationX">1 0 0 90</rotate>
              <rotate sid="rotationY">0 1 0 -90</rotate>
              <scale sid="scale">1 1 1</scale>
              <instance_node url="#ID3" />
            </node>
          </node>
        </visual_scene>
    </library_visual_scenes>
    <scene>
        <instance_visual_scene url="#EntireLayout" />
    </scene>
</COLLADA>
</pre>
</div>
</td>
<td align="center" bgcolor="lightgrey">[[File:Clock.png|250px|Clock]]</td>
</tr></table>