Extending iPanorama 360 can be a challenge, as none of the events are documented. You can talk to the developer or ask for support to get things done.

You can also read up on the core assets used:
ipanorama.min.js
jquery.ipanorama.min.js.

You can easily search for the events and figure out the parameters passed. Here a quick reference for things I used so far.

Main Events

ipanorama:ready
ipanorama:config
ipanorama:fullscreen
ipanorama:mode
ipanorama:transform-mode-changed

ipanorama:ready

ipanorama:config

ipanorama:fullscreen

ipanorama:mode

ipanorama:transform-mode-changed

Tooltip Events

ipanorama:tooltip-show
ipanorama:tooltip-hide

1 2	ipanorama:tooltip-show ipanorama:tooltip-hide

Popover Events

ipanorama:popover-show
ipanorama:popover-hide

1 2	ipanorama:popover-show ipanorama:popover-hide

Scene / Camera Events

ipanorama:scene-before-load
ipanorama:scene-after-load
ipanorama:scene-progress
ipanorama:scene-error
ipanorama:scene-show-start
ipanorama:scene-show-complete
ipanorama:scene-hide-start
ipanorama:scene-hide-complete
ipanorama:scene-clear
ipanorama:scene-index

ipanorama:scene-point-add
ipanorama:scene-point-remove
ipanorama:scene-point-dragstart
ipanorama:scene-point-dragend
ipanorama:scene-point-select
ipanorama:scene-point-deselect
ipanorama:scene-point-hide
ipanorama:scene-point-show
ipanorama:scene-point-change

ipanorama:scene-plane-add
ipanorama:scene-plane-remove
ipanorama:scene-plane-dragstart
ipanorama:scene-plane-dragend
ipanorama:scene-plane-select
ipanorama:scene-plane-deselect

ipanorama:scene-camera-start
ipanorama:scene-camera-end
ipanorama:scene-camera-change

ipanorama:scene-before-load

ipanorama:scene-after-load

ipanorama:scene-progress

ipanorama:scene-error

ipanorama:scene-show-start

ipanorama:scene-show-complete

ipanorama:scene-hide-start

ipanorama:scene-hide-complete

ipanorama:scene-clear

ipanorama:scene-index

ipanorama:scene-point-add

ipanorama:scene-point-remove

ipanorama:scene-point-dragstart

ipanorama:scene-point-dragend

ipanorama:scene-point-select

ipanorama:scene-point-deselect

ipanorama:scene-point-hide

ipanorama:scene-point-show

ipanorama:scene-point-change

ipanorama:scene-plane-add

ipanorama:scene-plane-remove

ipanorama:scene-plane-dragstart

ipanorama:scene-plane-dragend

ipanorama:scene-plane-select

ipanorama:scene-plane-deselect

ipanorama:scene-camera-start

ipanorama:scene-camera-end

ipanorama:scene-camera-change

Some Examples

Lock rotation

var instance = this,
$ = jQuery;

instance.$container.on("ipanorama:scene-after-load", function(e, data) {
    data.scene.control.minPolarAngle = 90 * Math.PI / 180;
    data.scene.control.maxPolarAngle = 90 * Math.PI / 180;
});

var instance = this,

$ = jQuery;

instance.$container.on("ipanorama:scene-after-load", function(e, data) {

data.scene.control.minPolarAngle = 90 * Math.PI / 180;

data.scene.control.maxPolarAngle = 90 * Math.PI / 180;

});

Custom Marker Click

var instance = this,
$ = jQuery;

function onMarkerClick(e) {
    var userData = this.cfg.userData;
    if(userData) {
        var $iframe = $(userData);
        $.featherlight($iframe);
    }
}

for(var i=0;i<instance.markers.length;i++) {
    var marker = instance.markers[i];
    marker.$marker.on('click', $.proxy(onMarkerClick, marker));
}

var instance = this,

$ = jQuery;

function onMarkerClick(e) {

var userData = this.cfg.userData;

if(userData) {

var $iframe = $(userData);

$.featherlight($iframe);

}

for(var i=0;i<instance.markers.length;i++) {

var marker = instance.markers[i];

marker.$marker.on('click', $.proxy(onMarkerClick, marker));

}

Custom loading

const plugin = this;
const $ = jQuery;
const $loading = $('<div>').addClass('myloading').text('loading');

plugin.$container.append($loading);

plugin.$container.on('ipanorama:scene-progress', (e, data) => {
   const flag = data.progress.loaded == data.progress.total;
   $loading.toggleClass('active', !flag);
});

const plugin = this;

const $ = jQuery;

const $loading = $('<div>').addClass('myloading').text('loading');

plugin.$container.append($loading);

plugin.$container.on('ipanorama:scene-progress', (e, data) => {

const flag = data.progress.loaded == data.progress.total;

$loading.toggleClass('active', !flag);

});

iPanorama 360 – Events / API