From 5ff2fcacb867c6697b7d591222fd86b57eb031ce Mon Sep 17 00:00:00 2001
From: Tom Payne <twpayne@gmail.com>
Date: Mon, 27 Jan 2014 14:39:40 +0100
Subject: [PATCH 1/4] Snap rotation when within 5 degrees instead of 0.1
 radians

---
 src/ol/rotationconstraint.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/ol/rotationconstraint.js b/src/ol/rotationconstraint.js
index 820f6cf3c8..0f6e3d2dea 100644
--- a/src/ol/rotationconstraint.js
+++ b/src/ol/rotationconstraint.js
@@ -1,6 +1,8 @@
 goog.provide('ol.RotationConstraint');
 goog.provide('ol.RotationConstraintType');
 
+goog.require('goog.math');
+
 
 /**
  * @typedef {function((number|undefined), number): (number|undefined)}
@@ -50,7 +52,7 @@ ol.RotationConstraint.createSnapToN = function(n) {
  * @return {ol.RotationConstraintType} Rotation constraint.
  */
 ol.RotationConstraint.createSnapToZero = function(opt_tolerance) {
-  var tolerance = opt_tolerance || 0.1;
+  var tolerance = opt_tolerance || goog.math.toRadians(5);
   return (
       /**
        * @param {number|undefined} rotation Rotation.

From 0a5ab24a0cc60f2e6a6b96973fb6753b3648b28f Mon Sep 17 00:00:00 2001
From: Tom Payne <twpayne@gmail.com>
Date: Mon, 27 Jan 2014 14:49:08 +0100
Subject: [PATCH 2/4] Add ol.RotationConstraint.disable

---
 src/ol/rotationconstraint.js | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/ol/rotationconstraint.js b/src/ol/rotationconstraint.js
index 0f6e3d2dea..fc73600f4e 100644
--- a/src/ol/rotationconstraint.js
+++ b/src/ol/rotationconstraint.js
@@ -10,6 +10,20 @@ goog.require('goog.math');
 ol.RotationConstraintType;
 
 
+/**
+ * @param {number|undefined} rotation Rotation.
+ * @param {number} delta Delta.
+ * @return {number|undefined} Rotation.
+ */
+ol.RotationConstraint.disable = function(rotation, delta) {
+  if (goog.isDef(rotation)) {
+    return 0;
+  } else {
+    return undefined;
+  }
+};
+
+
 /**
  * @param {number|undefined} rotation Rotation.
  * @param {number} delta Delta.

From 07a717d9679e39e0d5aaa986311502b506d00399 Mon Sep 17 00:00:00 2001
From: Tom Payne <twpayne@gmail.com>
Date: Mon, 27 Jan 2014 14:52:42 +0100
Subject: [PATCH 3/4] Add enableRotation option to ol.View2D

---
 src/objectliterals.jsdoc | 2 ++
 src/ol/view2d.js         | 9 +++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/objectliterals.jsdoc b/src/objectliterals.jsdoc
index 6c1c23e5f1..7963ec4487 100644
--- a/src/objectliterals.jsdoc
+++ b/src/objectliterals.jsdoc
@@ -91,6 +91,8 @@
  *     The coordinate system for the center is specified with the `projection`
  *     option. Default is `undefined`, and layer sources will not be fetched if
  *     this is not set.
+ * @property {boolean|undefined} enableRotation Enable rotation. Default is
+ *     `true`.
  * @property {ol.Extent|undefined} extent The extent that constrains the center,
  *     in other words, center cannot be set outside this extent.
  *     Default is `undefined`.
diff --git a/src/ol/view2d.js b/src/ol/view2d.js
index 057337f514..c7001a5096 100644
--- a/src/ol/view2d.js
+++ b/src/ol/view2d.js
@@ -569,6 +569,11 @@ ol.View2D.createResolutionConstraint_ = function(options) {
  * @return {ol.RotationConstraintType} Rotation constraint.
  */
 ol.View2D.createRotationConstraint_ = function(options) {
-  // FIXME rotation constraint is not configurable at the moment
-  return ol.RotationConstraint.createSnapToZero();
+  var enableRotation = goog.isDef(options.enableRotation) ?
+      options.enableRotation : true;
+  if (enableRotation) {
+    return ol.RotationConstraint.createSnapToZero();
+  } else {
+    return ol.RotationConstraint.disable;
+  }
 };

From 3196afb4c7ae21c8c94872354be858fd57ea753a Mon Sep 17 00:00:00 2001
From: Tom Payne <twpayne@gmail.com>
Date: Mon, 27 Jan 2014 15:13:50 +0100
Subject: [PATCH 4/4] Add constrainRotation option to ol.View2D

---
 src/objectliterals.jsdoc |  5 +++++
 src/ol/view2d.js         | 12 +++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/objectliterals.jsdoc b/src/objectliterals.jsdoc
index 7963ec4487..d4b3f57f80 100644
--- a/src/objectliterals.jsdoc
+++ b/src/objectliterals.jsdoc
@@ -91,6 +91,11 @@
  *     The coordinate system for the center is specified with the `projection`
  *     option. Default is `undefined`, and layer sources will not be fetched if
  *     this is not set.
+ * @property {boolean|number|undefined} constrainRotation Rotation constraint.
+ *     `false` means no constraint. `true` means no constraint, but snap to
+ *     zero near zero. A number constraints the rotation to that number of
+ *     values. For example, `4` will constrain the rotation to 0, 90, 180, and
+ *     270 degrees.  The default is `true`.
  * @property {boolean|undefined} enableRotation Enable rotation. Default is
  *     `true`.
  * @property {ol.Extent|undefined} extent The extent that constrains the center,
diff --git a/src/ol/view2d.js b/src/ol/view2d.js
index c7001a5096..6ddb3cd802 100644
--- a/src/ol/view2d.js
+++ b/src/ol/view2d.js
@@ -572,7 +572,17 @@ ol.View2D.createRotationConstraint_ = function(options) {
   var enableRotation = goog.isDef(options.enableRotation) ?
       options.enableRotation : true;
   if (enableRotation) {
-    return ol.RotationConstraint.createSnapToZero();
+    var constrainRotation = options.constrainRotation;
+    if (!goog.isDef(constrainRotation) || constrainRotation === true) {
+      return ol.RotationConstraint.createSnapToZero();
+    } else if (constrainRotation === false) {
+      return ol.RotationConstraint.none;
+    } else if (goog.isNumber(constrainRotation)) {
+      return ol.RotationConstraint.createSnapToN(constrainRotation);
+    } else {
+      goog.asserts.fail();
+      return ol.RotationConstraint.none;
+    }
   } else {
     return ol.RotationConstraint.disable;
   }