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Changes between Version 72 and Version 73 of content/LevelHowTo


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Timestamp:
Nov 18, 2015, 5:15:50 PM (9 years ago)
Author:
fvultier
Comment:

Added section that explains the orxonox coordinate system with a few examples.

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  • content/LevelHowTo

    v72 v73  
    9999}}}
    100100The attribute "scale" applies a uniform scale in all directions. By using the attribute "scale3d" you can define different scaling factors for the x-, y- and z-directions.
     101
     102== Coordinate system ==
     103Copy the following code to your level file to make the axis of the coordinate system visible. The x-axis is coloured red, the y-axis green and the z-axis is blue.
     104{{{
     105#!xml
     106<!-- Large coordinate axis -->
     107<Model position="0,0,0" mesh="Coordinates.mesh" scale="20"/>
     108}}}
     109Start the level and press the F1 button on the keyboard to display the position of the spaceship. Verify that the x component of the position increases if you fly along the x-axis (red).
     110Let's add a few models to the scene:
     111{{{
     112#!xml
     113<!-- Large coordinate axis -->
     114<Model position="0,0,0" mesh="Coordinates.mesh" scale="20"/>
     115
     116<!-- Example position and scale -->
     117<Model position="200,0,0" mesh="cube.mesh" scale="10"/>
     118<Model position="0,200,0" mesh="sphere.mesh" scale="3"/>
     119<Model position="0,0,200" mesh="cylinder.mesh" scale3D="3,3,10"/>
     120<Model position="0,100,100" mesh="rocket.mesh" scale="3"/>
     121<Model position="100,100,0" mesh="Coordinates.mesh" scale="3"/>
     122}}}
     123Fly to the models and verify their position.
     124Worldentities and therefore models (because the Model class inherits from the WorldEntity class) don't only have a position and a scale attribute. They also have an orientation. The orientation in three dimensional space is described by four numbers:
     125{{{
     126#!xml
     127<!-- Large coordinate axis -->
     128<Model position="0,0,0" mesh="Coordinates.mesh" scale="20"/>
     129
     130<!-- Example orientation -->
     131<Model position="100,100,0" orientation="1.0,2.0,3.0,4.0" mesh="Coordinates.mesh" scale="3"/>
     132}}}
     133These four numbers are called a "Quaternion". Because it is not obvious how these four numbers affect the orientation of an object we created the "direction" attribute for the WorldEntity class which is much simpler to use in level design.
     134{{{
     135#!xml
     136<!-- Large coordinate axis -->
     137<Model position="0,0,0" mesh="Coordinates.mesh" scale="20"/>
     138
     139<!-- Example direction -->
     140<!-- the -z axis of this model points in x-direction -->
     141<Model position="100,100,0" mesh="Coordinates.mesh" scale="3" direction="1,0,0"/>
     142<!-- the -z axis of this model points in the direction of the bisecting line of the angle between the x- and y-axis -->
     143<Model position="100,100,100" mesh="Coordinates.mesh" scale="3" direction="1,1,0"/>
     144}}}
     145The direction attribute specifies in what direction the -z axis of the WorldEntity points. The -z axis of the model at position (100,100,0) points in the x-direction which is parallel to the large red axis.
     146Another way to discribe the orientation of a WorldEntity is the "lookat" attribute:
     147{{{
     148#!xml
     149<!-- Large coordinate axis -->
     150<Model position="0,0,0" mesh="Coordinates.mesh" scale="20"/>
     151
     152<!-- Example lookat -->
     153<!-- the -z axis of all theese models point towards the cube -->
     154<Model position="50,50,50" mesh="cube.mesh" scale="3"/>
     155<Model position="100,100,0" mesh="Coordinates.mesh" scale="3" lookat="50,50,50"/>
     156<Model position="100,0,100" mesh="Coordinates.mesh" scale="3" lookat="50,50,50"/>
     157<Model position="0,100,100" mesh="Coordinates.mesh" scale="3" lookat="50,50,50"/>
     158<Model position="100,100,100" mesh="Coordinates.mesh" scale="3" lookat="50,50,50"/>
     159}}}
     160All four small "Coordinates.mesh" models look with their -z axis to the yellow cube located at (50,50,50).
     161Because the attributes orientation, direction and lookat all represent the same information always at most one of them should be specified. Don't do this:
     162{{{
     163#!xml
     164<!-- Too much information -->
     165<Model position="100,100,0" orientation="1.0,2.0,3.0,4.0" direction="0,100,0" lookat="0,100,100" mesh="Coordinates.mesh" scale="3"/>
     166}}}
     167There won't be any error message but the worldentity may not behave as expected.
    101168
    102169== MovableEntity - Let's get the world moving ==
     
    9411008
    9421009Export the concerning .blend file with the OgreMesh Exporter.
     1010
     1011
     1012
     1013
     1014Written by 'jo' and 'Fabien Vultier'