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https://issues.apache.org/jira/browse/SIS-318?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Martin Desruisseaux updated SIS-318:
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Affects Version/s: 0.7
0.8
> Support PassThroughTransform directly into AbstractMathTransform
> ----------------------------------------------------------------
>
> Key: SIS-318
> URL: https://issues.apache.org/jira/browse/SIS-318
> Project: Spatial Information Systems
> Issue Type: Improvement
> Components: Referencing
> Affects Versions: 0.5, 0.6, 0.7, 0.8
> Reporter: Martin Desruisseaux
> Priority: Minor
> Labels: performance
>
> Move the {{firstAffectedOrdinate}} and {{numTrailingOrdinates}} fields from
> {{PassThroughTransform}} to its {{AbstractMathTransform}} parent class. Every
> {{AbstractMathTransform}} subclasses should then take those fields in
> account. We expect no performance penalty on {{AbstractMathTransform}}
> subclasses since it would just change the value in an addition which is
> applied anyway. On the other hand, it may provide significant performance
> gain by reducing the need for the {{PassThroughTransform}}, which can hardly
> implement the {{transform}} method in an efficient way.
> It would also make easier to concatenate the matrices of linear transforms.
> In the current implementation we lost a concatenation opportunity if one
> linear transform is the last {{MathTransform}} (in a chain of a concatenated
> transforms) inside the {{PassThroughTransform}}, while the other linear
> transform is the first {{MathTransform}} outside the
> {{PassThroughTransform}}. We could move the former linear transform outside
> the {{PassThroughTransform}}, but it cause confusing WKT to be formatted if
> the transforms inside the {{PassThroughTransform}} have a
> {{ContextualParameters}}. We expect that this problem would be solved with
> the fix proposed in this issue.
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