Improve unstepped contours mapping of color and range.

For stepped data, the range values need to have one more entry than the
color values, since the range values define the divisions where colors
change.  For non-stepped data, we were still asking for one more range
entry than color entry, but the final range entry was not used.  Allow a
one-to-one mapping for non-stepped data, as this is more obvious.

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Change Log
 
+## Unreleased
+
+### Improvements
+- Contours with continuous (unstepped) data can specify the same number of values in `rangeValues` and `colorRange`
+
 ## Version 1.0.0
 
 ### Improvements

src/contourFeature.js

@@ -40,6 +40,7 @@ var meshFeature = require('./meshFeature');
  * passed the {@link geo.meshFeature.meshInfo} object.
  *
  * @typedef {geo.meshFeature.meshSpec} geo.contourFeature.contourSpec
+ * @extends geo.meshFeature.meshSpec
  * @property {number} [min] Minimum contour value.  If unspecified, taken from
  *    the computed minimum of the `value` style.
  * @property {number} [max] Maximum contour value.  If unspecified, taken from
@@ -63,7 +64,8 @@ var meshFeature = require('./meshFeature');
  * @property {number[]} [rangeValues] An array used to map values to the
  *    `colorRange`.  By default, values are spaced linearly.  If specified, the
  *    entries must be increasing weakly monotonic, and there must be one more
- *    entry then the length of `colorRange`.
+ *    entry then the length of `colorRange` if the contour is stepped, or the
+ *    same length as the `colorRange` if unstepped.
  */
 
 /**
@@ -162,7 +164,9 @@ var contourFeature = function (arg) {
     minmax = util.getMinMaxValues(result.value, contour.get('min')(result), contour.get('max')(result));
     result.minValue = minmax.min;
     result.maxValue = minmax.max;
-    if (!rangeValues || rangeValues.length !== result.colorMap.length + 1) {
+    if (!rangeValues || !result.colorMap ||
+        (rangeValues.length !== result.colorMap.length + 1 && (
+          stepped || rangeValues.length !== result.colorMap.length))) {
       rangeValues = null;
     }
     if (rangeValues) {  /* ensure increasing monotonicity */

src/webgl/contourFeature.frag

@@ -25,7 +25,7 @@ void main () {
         step = steps - 0.5;
       }
     } else {
-      step = valueVar;
+      step = valueVar + 0.5;
     }
     // our texture is padded on either end by a repeated value to ensure
     // we interpolate smoothly at the ends.

tests/cases/contourFeature.js

@@ -275,5 +275,45 @@ describe('Contour Feature', function () {
       expect(result.elements.length).toBe(21); /* 7 tri. * 3 pts. */
       expect(result.pos.length).toBe(24); /* 8 distinct points * 3 coor. */
     });
+
+    it('stepped range and color', function () {
+      var contour1 = {
+        gridWidth: 7,
+        gridHeight: 2,
+        x0: -30,
+        y0: -30,
+        dx: 6,
+        dy: 6,
+        colorRange: ['red', 'black', 'blue'],
+        rangeValues: [0, 6, 12, 15],
+        values: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13],
+        stepped: true
+      };
+      var contour = layer.createFeature('contour', {
+        contour: contour1, style: {value: 0}}).data(contour1.values);
+      var result = contour._createContours();
+      expect(result.rangeValues.length).toBe(4);
+      expect(result.factor).toBe(0.2);
+    });
+
+    it('continuous range and color', function () {
+      var contour1 = {
+        gridWidth: 7,
+        gridHeight: 2,
+        x0: -30,
+        y0: -30,
+        dx: 6,
+        dy: 6,
+        colorRange: ['red', 'black', 'blue'],
+        rangeValues: [0, 6, 15],
+        values: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13],
+        stepped: false
+      };
+      var contour = layer.createFeature('contour', {
+        contour: contour1, style: {value: 0}}).data(contour1.values);
+      var result = contour._createContours();
+      expect(result.rangeValues.length).toBe(3);
+      expect(result.factor).toBe(0.2);
+    });
   });
 });

tests/external-data/base-images.tgz.sha512

@@ -1 +1 @@
-81bfb7b494d0c93b3992bed1ef9f3c505c8f5959c6b07951b0ce421f197921bb1ed5d3f650344361078fa2184acefad3a0a21057f13b122bb573e2fc34f63c7e
+346dcdcf6e88aa9bfde684a311a452431af01b055f007e73839d42aa19ce0846af20d0bc296f7e1acca0af2759896d647dbbdbf07b20428f0e10464a1764c77e