Add ol.vec.Mat4.multVec2

src/ol/vec/mat4.js

@@ -90,3 +90,23 @@ ol.vec.Mat4.makeSaturation = function(matrix, value) {
       v03, v13, v23, v33);
   return matrix;
 };
+
+
+/**
+ * Transforms the given vector with the given matrix storing the resulting,
+ * transformed vector into resultVec. The input vector is multiplied against the
+ * upper 2x4 matrix omitting the projective component.
+ *
+ * @param {goog.vec.Mat4.AnyType} mat The matrix supplying the transformation.
+ * @param {Array.<number>} vec The 3 element vector to transform.
+ * @param {Array.<number>} resultVec The 3 element vector to receive the results
+ *     (may be vec).
+ * @return {Array.<number>} return resultVec so that operations can be
+ *     chained together.
+ */
+ol.vec.Mat4.multVec2 = function(mat, vec, resultVec) {
+  var x = vec[0], y = vec[1];
+  resultVec[0] = x * mat[0] + y * mat[4] + mat[12];
+  resultVec[1] = x * mat[1] + y * mat[5] + mat[13];
+  return resultVec;
+};