ashatora/openlayers
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Add comment to explain calculation.

Browse Source
This commit is contained in:
philip
2020-04-02 14:14:13 +00:00
parent ccf3532eb2
commit 72907566bb
1 changed files with 10 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
src/ol/reproj/Triangulation.js
View File

@@ -139,6 +139,16 @@ class Triangulation {
const sourceBottomRight = this.transformInv_(destinationBottomRight);
const sourceBottomLeft = this.transformInv_(destinationBottomLeft);
/*
* The maxSubdivision controls how many splittings of the target area can
* be done. The idea here is to do a linear mapping of the target areas
* but the actual overal reprojection (can be) extremely non-linear. The
* default value of MAX_SUBDIVISION was chosen based on mapping a 256x256
* tile size. However this function is also called to remap canvas rendered
* layers which can be much larger. This calculation increases the maxSubdivision
* value by the right factor so that each 256x256 pixel area has
* MAX_SUBDIVISION divisions.
*/
const maxSubdivision = MAX_SUBDIVISION + (opt_destinationResolution ?
Math.max(0, Math.ceil(Math.log2(getArea(targetExtent) /
(opt_destinationResolution * opt_destinationResolution * 256 * 256))))