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Reproject every image only once per triangle

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If the triangle has to be shifted, determine if the image has to be rendered shifted or not.
This commit is contained in:
Petr Sloup
2015-06-04 17:46:39 +02:00
parent 6e08fc9e13
commit bc74273208
1 changed files with 14 additions and 28 deletions
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42
src/ol/reproj/reproj.js
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@@ -58,23 +58,12 @@ ol.reproj.calculateSourceResolution = function(sourceProj, targetProj,
ol.reproj.renderTriangles = function(context,
sourceResolution, targetResolution, targetExtent, triangulation, sources) {
var renderImage = function(image) {
context.scale(sourceResolution, -sourceResolution);
// the image has to be scaled by half a pixel in every direction
// in order to prevent artifacts between the original tiles
// that are introduced by the canvas antialiasing.
context.drawImage(image, -0.5, -0.5,
image.width + 1, image.height + 1);
};
var shiftDistance = triangulation.shiftDistance;
var targetTL = ol.extent.getTopLeft(targetExtent);
goog.array.forEach(triangulation.triangles, function(tri, i, arr) {
context.save();
var targetTL = ol.extent.getTopLeft(targetExtent);
/* Calculate affine transform (src -> dst)
* Resulting matrix can be used to transform coordinate
* from `sourceProjection` to destination pixels.
@@ -150,24 +139,21 @@ ol.reproj.renderTriangles = function(context,
goog.array.forEach(sources, function(src, i, arr) {
context.save();
var tlSrcFromData = ol.extent.getTopLeft(src.extent);
context.translate(tlSrcFromData[0], tlSrcFromData[1]);
if (tri.needsShift) {
context.save();
var dataTL = ol.extent.getTopLeft(src.extent);
context.translate(dataTL[0], dataTL[1]);
// if the triangle needs to be shifted (because of the dateline wrapping),
// shift only the source images that need it
if (tri.needsShift && dataTL[0] < 0) {
context.translate(shiftDistance, 0);
renderImage(src.image);
context.restore();
renderImage(src.image);
if (goog.DEBUG) {
context.fillStyle =
sources.length > 16 ? 'rgba(255,0,0,1)' :
(sources.length > 4 ? 'rgba(0,255,0,.3)' : 'rgba(0,0,255,.1)');
context.fillRect(0, 0, 256, 256);
}
} else {
renderImage(src.image);
}
context.scale(sourceResolution, -sourceResolution);
// the image has to be scaled by half a pixel in every direction
// in order to prevent artifacts between the original tiles
// that are introduced by the canvas antialiasing.
context.drawImage(src.image, -0.5, -0.5,
src.image.width + 1, src.image.height + 1);
context.restore();
});