mock and fix for surface plot with empty z array

required minimum 2x2 data for a surface

revised conditions for z

correct z length check

new baseline added

Author: archmoj

src/traces/surface/defaults.js

@@ -23,14 +23,18 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
         return Lib.coerce(traceIn, traceOut, attributes, attr, dflt);
     }
 
+    var x = coerce('x');
+    var y = coerce('y');
+
     var z = coerce('z');
-    if(!z) {
+    if(!z || !z.length ||
+       (x ? (x.length < 2) : false) ||
+       (y ? (y.length < 2) : false)
+    ) {
         traceOut.visible = false;
         return;
     }
 
-    var x = coerce('x');
-    coerce('y');
 
     traceOut._xlength = (Array.isArray(x) && Lib.isArrayOrTypedArray(x[0])) ? z.length : z[0].length;
     traceOut._ylength = z.length;

test/image/baselines/gl3d_surface-with-no-z-data.png

@@ -0,0 +1,33 @@
+{
+    "data": [
+      {
+        "type": "surface",
+        "x": [],
+        "y": [],
+        "z": []
+      },
+      {
+        "type": "surface",
+        "x": [0],
+        "y": [0],
+        "z": [[1]]
+      },
+      {
+        "type": "surface",
+        "x": [0, 1, 2],
+        "y": [0],
+        "z": [[1, 2, 3]]
+      },
+      {
+        "type": "surface",
+        "x": [0],
+        "y": [0, 1, 2],
+        "z": [[1, 2, 3]]
+      }
+    ],
+    "layout": {
+        "title": "Surface traces with rows/columns less than two<br>or with no Z data would be invisible.",
+        "width": 600,
+        "height": 400
+    }
+}