README edit for npm build

[cainesap]

Hi,
For those new to npm (like me), it would be very helpful to add npm install as an instruction in the README before trying to build.
Also for me I needed to run: npm install -g polyfills; npm install -g rollup; npm install -g derequire; npm install -g browserify; npm install -g uglify-js
Thanks for the great resource!

[jenbhu]

Yes, had to do the same !

[alfski]

Yes do this. Now there's no pre-built vrview.js and the developers.google.com/vr/concepts/vrview-web page directs to github, we need instructions for noobs under 'Building'.

A simple npm install worked for me.

[omniviewer360]

Hi all, it seems I've also had exactly the same issue. Got to the end of the supplied instructions and instead of a navigable 360 panorama window it was just a black square.
Luckily I discovered this thread. Quick question I've followed the above instructions and ran an npm install followed by the above written commands in the CMD window inside the /vrview directory. I still have the black square of no action :-( any thoughts? Cheers!

[michelePap]

Hi, i'm new to the npm build system, what's the correct way to build the library? I have added all the missing packages for npm but i still have some errors:
src/third_party/three/Three.js → build/three.js... [!] Error: You must specify options.format, which can be one of 'amd', 'cjs', 'es', 'iife' or 'umd' https://rollupjs.org/#format-f-output-format-

[michelePap]

Solved: need to update rollup.config.js in src/third_party/three/
This:

export default {
	entry: 'src/third_party/three/Three.js',
	dest: 'build/three.js',
	moduleName: 'THREE',
	format: 'umd',
	plugins: [
		glsl()
	],
	outro: outro
};

become:

export default {
	input: 'src/third_party/three/Three.js',
	output: {
		file: 'build/three.js',
		name: 'THREE',
		format: 'umd',
	},
	plugins: [
		glsl()
	],
	outro: outro
};