Add ol.reproj

2015-05-25 10:55:14 +02:00
parent 44a64ba451
commit 1222287f22
4 changed files with 669 additions and 0 deletions
@@ -0,0 +1,104 @@
+goog.provide('ol.reproj.Triangulation');
+goog.provide('ol.reproj.triangulation');
+
+goog.require('goog.array');
+goog.require('goog.math');
+goog.require('ol.extent');
+
+
+/**
+ * Array of triangles,
+ *   each triangles is Array (length=3) of
+ *   projected point pairs (length=2; [src, dst]),
+ *   each point is ol.Coordinate.
+ * @typedef {Array.<Array.<Array.<ol.Coordinate>>>}
+ */
+ol.reproj.Triangulation;
+
+
+/**
+ * Triangulates given extent and reprojects vertices.
+ * TODO: improved triangulation, better error handling of some trans fails
+ * @param {ol.Extent} extent
+ * @param {ol.TransformFunction} transformInv Inverse transform (dst -> src).
+ * @param {number=} opt_subdiv Subdivision factor (default 4).
+ * @return {ol.reproj.Triangulation}
+ */
+ol.reproj.triangulation.createForExtent = function(extent, transformInv,
+                                                   opt_subdiv) {
+  var triangulation = [];
+
+  var tlDst = ol.extent.getTopLeft(extent);
+  var brDst = ol.extent.getBottomRight(extent);
+
+  var projected = {0: {}}; // cache of already transformed values
+  var subdiv = opt_subdiv || 4;
+  for (var y = 0; y < subdiv; y++) {
+    projected[y + 1] = {}; // prepare cache for the next line
+    for (var x = 0; x < subdiv; x++) {
+      // do 2 triangle: [(x, y), (x + 1, y + 1), (x, y + 1)]
+      //                [(x, y), (x + 1, y), (x + 1, y + 1)]
+
+      var x0y0dst = [
+        goog.math.lerp(tlDst[0], brDst[0], x / subdiv),
+        goog.math.lerp(tlDst[1], brDst[1], y / subdiv)
+      ];
+      var x1y0dst = [
+        goog.math.lerp(tlDst[0], brDst[0], (x + 1) / subdiv),
+        goog.math.lerp(tlDst[1], brDst[1], y / subdiv)
+      ];
+      var x0y1dst = [
+        goog.math.lerp(tlDst[0], brDst[0], x / subdiv),
+        goog.math.lerp(tlDst[1], brDst[1], (y + 1) / subdiv)
+      ];
+      var x1y1dst = [
+        goog.math.lerp(tlDst[0], brDst[0], (x + 1) / subdiv),
+        goog.math.lerp(tlDst[1], brDst[1], (y + 1) / subdiv)
+      ];
+
+      if (!goog.isDef(projected[y][x])) {
+        projected[y][x] = transformInv(x0y0dst);
+      }
+      if (!goog.isDef(projected[y][x + 1])) {
+        projected[y][x + 1] = transformInv(x1y0dst);
+      }
+      if (!goog.isDef(projected[y + 1][x])) {
+        projected[y + 1][x] = transformInv(x0y1dst);
+      }
+      if (!goog.isDef(projected[y + 1][x + 1])) {
+        projected[y + 1][x + 1] = transformInv(x1y1dst);
+      }
+
+      triangulation.push(
+          [
+            [projected[y][x], x0y0dst],
+            [projected[y + 1][x + 1], x1y1dst],
+            [projected[y + 1][x], x0y1dst]
+          ], [
+            [projected[y][x], x0y0dst],
+            [projected[y][x + 1], x1y0dst],
+            [projected[y + 1][x + 1], x1y1dst]
+          ]
+      );
+    }
+  }
+
+  return triangulation;
+};
+
+
+/**
+ * @param {ol.reproj.Triangulation} triangulation
+ * @return {ol.Extent}
+ */
+ol.reproj.triangulation.getSourceExtent = function(triangulation) {
+  var extent = ol.extent.createEmpty();
+
+  goog.array.forEach(triangulation, function(triangle, i, arr) {
+    ol.extent.extendCoordinate(extent, triangle[0][0]);
+    ol.extent.extendCoordinate(extent, triangle[1][0]);
+    ol.extent.extendCoordinate(extent, triangle[2][0]);
+  });
+
+  return extent;
+};