Update viewpoint option

src/doc/en/reference/plot3d/threejs.rst

@@ -59,7 +59,7 @@ Options currently supported by the viewer:
 
 - ``thickness`` -- (default: 1) numeric value for thickness of lines
 
-- ``viewpoint`` -- (default: None) string of the form '[x,y,z],angle' setting the initial viewpoint
+- ``viewpoint`` -- (default: None) string of the form [[x,y,z],angle] setting the initial viewpoint
   of the scene; can be determined using the 'Get Viewpoint' option of the information menu
 
 Clicking on the information icon in the lower right-hand corner of the viewer opens

src/sage/ext_data/threejs/threejs_template.html

@@ -152,9 +152,9 @@
 
     if ( options.viewpoint ) {
 
-        var aa = options.viewpoint.replace('[','').replace(']','').split(',');
-        var axis = new THREE.Vector3( aa[0], aa[1], aa[2] );
-        var angle = aa[3] * Math.PI / 180;
+        var aa = options.viewpoint;
+        var axis = new THREE.Vector3( aa[0][0], aa[0][1], aa[0][2] ).normalize();
+        var angle = aa[1] * Math.PI / 180;
         var q = new THREE.Quaternion().setFromAxisAngle( axis, angle ).inverse();
 
         offset.set( 0, 0, offset.length() );

src/sage/plot/plot3d/base.pyx

@@ -385,6 +385,15 @@ cdef class Graphics3d(SageObject):
         js_options['aspectRatio'] = [float(i) for i in js_options['aspectRatio']]
         js_options['decimals'] = int(js_options['decimals'])
 
+        if js_options['viewpoint']:
+            import warnings
+            if len(js_options['viewpoint']) != 2 or len(js_options['viewpoint'][0]) != 3:
+                warnings.warn('viewpoint must be of the form [[x,y,z],angle]')
+                js_options['viewpoint'] = False
+            else:
+                js_options['viewpoint'][0] = [float(i) for i in js_options['viewpoint'][0]]
+                js_options['viewpoint'][1] = float(js_options['viewpoint'][1])
+
         if not js_options['frame']:
             js_options['axesLabels'] = False