Coordinates: Difference between revisions
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Note:'Global' or 'absolute' coordinates refer to the coordinates of the world. All other coordinate systems are 'local' to an entity.
Tip:SDK tools generally align coordinates so that the camera is looking down Y, since this tends to have the effect of making the item in question face you. Remember that this makes X appear reversed.
Tip:There can be multiple origins within the same entity: its own origin, the origin of its model, etc. Each origin defines its own local coordinate system relative to its parent.
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<div style="float:right;padding:1em;background:white;">[[Image:Coordinates.png|A two-dimensional coordinate system]]</div> | <div style="float:right;padding:1em;background:white;">[[Image:Coordinates.png|A two-dimensional coordinate system]]</div> | ||
'''Coordinates''' are used to describe locations. | '''Coordinates''' are used to describe locations. Each one is a group of "ordinate" numbers which taken together can be plotted on a grid, one ordinate per dimension. | ||
Coordinates in Source are <code>(<span style="color:red;font-weight:bold;">X</span>,<span style="color:green;font-weight:bold;">Y</span>,<span style="color:blue;font-weight:bold;">Z</span>)</code>, where X is right, Y is forward, and Z is up. <code>(0,0,1)</code> is a point one [[unit]] directly above the origin. | Coordinates in Source are <code>(<span style="color:red;font-weight:bold;">X</span>,<span style="color:green;font-weight:bold;">Y</span>,<span style="color:blue;font-weight:bold;">Z</span>)</code>, where X is right, Y is forward, and Z is up. <code>(0,0,1)</code> is a point one [[unit]] directly above the origin. | ||
Revision as of 10:50, 12 April 2009
Coordinates are used to describe locations. Each one is a group of "ordinate" numbers which taken together can be plotted on a grid, one ordinate per dimension.
Coordinates in Source are (X,Y,Z), where X is right, Y is forward, and Z is up. (0,0,1) is a point one unit directly above the origin.
Coordinates are often stored alongside a set of rotation angles.
Note:'Global' or 'absolute' coordinates refer to the coordinates of the world. All other coordinate systems are 'local' to an entity.Tip:SDK tools generally align coordinates so that the camera is looking down Y, since this tends to have the effect of making the item in question face you. Remember that this makes X appear reversed.Origin
The origin of an object is the point at which its local coordinates are (0,0,0). This is the 'centre' from which all other local coordinate values are relative.
Tip:There can be multiple origins within the same entity: its own origin, the origin of its model, etc. Each origin defines its own local coordinate system relative to its parent.See also
- Wikipedia:Coordinate system
- $origin and $autocenter (for models)