If you load models or textures from external files, due to browsers' [link:http://en.wikipedia.org/wiki/Same_origin_policy same origin policy] security restrictions, loading from a file system will fail with a security exception.
There are two ways to solve this:
file:///yourFile.html
http://localhost/yourFile.html
If you use option 1, be aware that you may open yourself to some vulnerabilities if using the same browser for a regular web surfing. You may want to create a separate browser profile / shortcut used just for local development to be safe. Let's go over each option in turn.
Many programming languages have simple HTTP servers built in. They are not as full featured as production servers such as [link:https://www.apache.org/ Apache] or [link:https://nginx.org NGINX], however they should be sufficient for testing your three.js application.
Node.js has a simple HTTP server package. To install:
npm install http-server -g
To run (from your local directory):
http-server . -p 8000
If you have [link:http://python.org/ Python] installed, it should be enough to run this from a command line (from your working directory):
//Python 2.x
python -m SimpleHTTPServer
//Python 3.x
python -m http.server
This will serve files from the current directory at localhost under port 8000, i.e in the address bar type:
http://localhost:8000/
If you have Ruby installed, you can get the same result running this instead:
ruby -r webrick -e "s = WEBrick::HTTPServer.new(:Port => 8000, :DocumentRoot => Dir.pwd); trap('INT') { s.shutdown }; s.start"
PHP also has a built-in web server, starting with php 5.4.0:
php -S localhost:8000
Lighttpd is a very lightweight general purpose webserver. We'll cover installing it on OSX with HomeBrew here. Unlike the other servers discussed here, lighttpd is a full fledged production ready server.
brew install lighttpd
lighttpd -f lighttpd.conf
Enable the develop menu using the preferences panel, under Advanced -> "Show develop menu in menu bar".
Then from the safari "Develop" menu, select "Disable local file restrictions", it is also worth noting safari has some odd behaviour with caches, so it is advisable to use the "Disable caches" option in the same menu; if you are editing & debugging using safari.
Close all running Chrome instances first. The important word here is 'all'.
On Windows, you may check for Chrome instances using the Windows Task Manager. Alternatively, if you see a Chrome icon in the system tray, then you may open its context menu and click 'Exit'. This should close all Chrome instances.
Then start the Chrome executable with a command line flag:
chrome --allow-file-access-from-files
On Windows, probably the easiest is probably to create a special shortcut icon which has added the flag given above (right-click on shortcut -> properties -> target).
On Mac OSX, you can do this with
open /Applications/Google\ Chrome.app --args --allow-file-access-from-files
about:config
security.fileuri.strict_origin_policy
parameter
Other simple alternatives are [link:http://stackoverflow.com/q/12905426/24874 discussed here] on Stack Overflow.