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Simplify triangle-shifting logic for reprojection

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This commit is contained in:
Petr Sloup
2015-06-09 14:28:44 +02:00
parent 3f567b0bf0
commit 9b82f19cc2
3 changed files with 40 additions and 23 deletions
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src/ol/reproj/reproj.js
+14 -8
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@@ -49,6 +49,7 @@ ol.reproj.calculateSourceResolution = function(sourceProj, targetProj,
* Renders the source into the canvas based on the triangulation.
* @param {CanvasRenderingContext2D} context
* @param {number} sourceResolution
* @param {ol.Extent} sourceExtent
* @param {number} targetResolution
* @param {ol.Extent} targetExtent
* @param {ol.reproj.Triangulation} triangulation
@@ -56,9 +57,13 @@ ol.reproj.calculateSourceResolution = function(sourceProj, targetProj,
* image: (HTMLCanvasElement|Image)}>} sources
*/
ol.reproj.renderTriangles = function(context,
sourceResolution, targetResolution, targetExtent, triangulation, sources) {
sourceResolution, sourceExtent, targetResolution, targetExtent,
triangulation, sources) {
var shiftDistance = triangulation.shiftDistance;
var shiftDistance = !goog.isNull(sourceExtent) ?
ol.extent.getWidth(sourceExtent) : null;
var shiftThreshold = !goog.isNull(sourceExtent) ?
(sourceExtent[0] + sourceExtent[2]) / 2 : null;
var targetTL = ol.extent.getTopLeft(targetExtent);
goog.array.forEach(triangulation.triangles, function(tri, i, arr) {
@@ -91,10 +96,10 @@ ol.reproj.renderTriangles = function(context,
var u0 = tgt[0][0] - targetTL[0], v0 = -(tgt[0][1] - targetTL[1]),
u1 = tgt[1][0] - targetTL[0], v1 = -(tgt[1][1] - targetTL[1]),
u2 = tgt[2][0] - targetTL[0], v2 = -(tgt[2][1] - targetTL[1]);
if (tri.needsShift) {
x0 = goog.math.modulo(x0 + shiftDistance, shiftDistance);
x1 = goog.math.modulo(x1 + shiftDistance, shiftDistance);
x2 = goog.math.modulo(x2 + shiftDistance, shiftDistance);
if (tri.needsShift && !goog.isNull(shiftDistance)) {
x0 = goog.math.modulo(x0, shiftDistance);
x1 = goog.math.modulo(x1, shiftDistance);
x2 = goog.math.modulo(x2, shiftDistance);
}
var augmentedMatrix = [
[x0, y0, 1, 0, 0, 0, u0 / targetResolution],
@@ -142,8 +147,9 @@ ol.reproj.renderTriangles = function(context,
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) {
// shift back only the source images that need it
if (tri.needsShift && !goog.isNull(shiftDistance) &&
dataTL[0] < shiftThreshold) {
context.translate(shiftDistance, 0);
}
context.scale(sourceResolution, -sourceResolution);