Difference between revisions of "Object Scale"
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Flowcode represents an objects [[Object position|position]] in terms of [[Object coordinates|coordinates]], '''scale''' and [[Object rotation|rotation]]. | Flowcode represents an objects [[Object position|position]] in terms of [[Object coordinates|coordinates]], '''scale''' and [[Object rotation|rotation]]. | ||
| − | Internally an objects scale is kept as a ''scale factor'' in the X, Y and Z axis. When accessing the [[API overview|SIM API]] this is the value that is altered, and relates to the diagonal of a transform matrix: | + | Internally an objects scale is kept as a ''scale factor'' in the X, Y and Z axis of the object. When accessing the [[API overview|SIM API]] this is the value that is altered, and relates to the diagonal of a transform matrix: |
::[[File:scale_matrix.png]] | ::[[File:scale_matrix.png]] | ||
| − | This is a | + | This is a transformation applied to the object which alters the size of it, and when rendered on the panel of all its child objects. |
| − | + | All API functions deal with this scale - this is mainly because the calculations involved in converting to other representations and back every time scale needs to be set would slow the programs down, but also because conversion to other representations can result in rounding errors and inaccuracies when combined with rotation. | |
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| − | + | == Scale vs Size== | |
| + | The scale factors of an object describes its dimensions without considering any child objects, and as such will not be affected if any other object on the panel changes its location, size or orientation. | ||
| + | The ''absolute size'' of an object can be thought of as the product of its scale multiplied by all its child scales. | ||
| − | + | This can be thought of as the size of the bounding box of the object. This can be read through the API call [[API Panel.Position.GetBox|GetBox]]. | |
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| + | Unlike scale, the ''size'' of an object depends on the children of that object. Though it may be more intuitive to think of size instead of scale, and therefore size is used in the properties pane, internally and in the exposed [[API Panel.Position|API]] Flowcode uses scale, as this is much quicker to calculate and easier to control. | ||
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Revision as of 22:02, 8 May 2013
This article refers to the representation of an object drawn on either the System panel or the Dashboard panel.
Flowcodes representation of scale
Flowcode represents an objects position in terms of coordinates, scale and rotation.
Internally an objects scale is kept as a scale factor in the X, Y and Z axis of the object. When accessing the SIM API this is the value that is altered, and relates to the diagonal of a transform matrix:
This is a transformation applied to the object which alters the size of it, and when rendered on the panel of all its child objects.
All API functions deal with this scale - this is mainly because the calculations involved in converting to other representations and back every time scale needs to be set would slow the programs down, but also because conversion to other representations can result in rounding errors and inaccuracies when combined with rotation.
Scale vs Size
The scale factors of an object describes its dimensions without considering any child objects, and as such will not be affected if any other object on the panel changes its location, size or orientation.
The absolute size of an object can be thought of as the product of its scale multiplied by all its child scales.
This can be thought of as the size of the bounding box of the object. This can be read through the API call GetBox.
Unlike scale, the size of an object depends on the children of that object. Though it may be more intuitive to think of size instead of scale, and therefore size is used in the properties pane, internally and in the exposed API Flowcode uses scale, as this is much quicker to calculate and easier to control.
Local and world space
- Main article: Local and world space
When working with objects in the flowchart, local coordinates are always preferred over world coordinates. This is so that scaling an objects parent does not affect the 'coordinate space' of the program - moving to coordinates (1, 2, 3) will always move to the same point in the component, despite the users scaling of the component, which is out of the component authors control.
It is very difficult to program an object to behave as expected in all circumstances using the world position.
To calculate the world size from an objects local scale, this must be multiplied by the scales of all the objects children and parents in the Component tree.
