improve streamtube attr descriptions

Author: etpinard

src/traces/streamtube/attributes.js

@@ -21,19 +21,19 @@ var attrs = {
         valType: 'data_array',
         role: 'info',
         editType: 'calc+clearAxisTypes',
-        description: 'Sets the x coordinates of the vector field'
+        description: 'Sets the x coordinates of the vector field.'
     },
     y: {
         valType: 'data_array',
         role: 'info',
         editType: 'calc+clearAxisTypes',
-        description: 'Sets the y coordinates of the vector field'
+        description: 'Sets the y coordinates of the vector field.'
     },
     z: {
         valType: 'data_array',
         role: 'info',
         editType: 'calc+clearAxisTypes',
-        description: 'Sets the z coordinates of the vector field'
+        description: 'Sets the z coordinates of the vector field.'
     },
 
     u: {
@@ -57,23 +57,20 @@ var attrs = {
         editType: 'calc',
         description: [
             'Sets the x components of the starting position of the streamtubes',
-            ''
         ].join(' ')
     },
     starty: {
         valType: 'data_array',
         editType: 'calc',
         description: [
             'Sets the y components of the starting position of the streamtubes',
-            ''
         ].join(' ')
     },
     startz: {
         valType: 'data_array',
         editType: 'calc',
         description: [
             'Sets the z components of the starting position of the streamtubes',
-            ''
         ].join(' ')
     },
 

src/traces/streamtube/index.js

@@ -22,9 +22,16 @@ module.exports = {
 
     meta: {
         description: [
-            'Use streamtube trace to visualize flow in a vector field',
+            'Use streamtube trace to visualize flow in a vector fields.',
             '',
-            '....'
+            'Specify a vector field using 6 1D arrays of equal length,',
+            '3 position arrays `x`, `y` and `z`',
+            'and 3 vector component arrays `u`, `v`, `w`.',
+            '',
+            'By default, the tubes\' starting positions will be cut from the vector field\'s',
+            'x-z plane at its minimum y value.',
+            'To specify your own starting position, use attributes `startx`, `starty`',
+            'and `startz`.'
         ].join(' ')
     }
 };