Portal Mechanics (Closes #130)

[heisluft]

This PR implements the creation of nether portals and implements the actual travelling to the nether via portal as well as generating portals in the nether. It also implements any Bukkit / Spigot / PaperSpigot Event related to Portals and their mechanics.
This will fix one of Glowstone´s oldest issues while greatly expanding it´s functionality as a vanilla server.

What is implemented:

• Creation of nether portals by players
• Destroying Nether Portals
• Zombie Pigman Portal spawns
• Stubs of a TravelAgent (Thank you, @VaiTon )
• Generating and linking portals
• Travelling to the nether
• Bukkit Portal related Event implementations
• BUGFIX: Players somehow cannot see portal blocks

[heisluft]

This is where I'm at now
State of development

[VaiTon]

This is where I'm at now
State of development

Good job man!

[heisluft]

Next sneak peak (chance of zombie pigman spawning increased by 1000% to shorten video length :))

[VaiTon]

I think it would be better if we implemented two TravelAgents, one for nether worlds and one for end ones.

[heisluft]

My take on this is that each GlowWorld registers one TravelAgentImpl which then deals with portal implementation.
This also would allow us to handle Portal gen in the overworld - as Overworlds need to register both a Nether and an EndTravelAgent. getTravelAgent() in Entity/PlayerPortalEvent is not strictly required to return a consistent travelAgent but two implementations would just increase complexity (as the actual porting method is the same in both nether and end portals). Of course we could define a shared superclass but managing 3 classes + different handlers in the World class looks cumbersome to me compared to one, capable-of-everything class which can be referred to by each world in the same manner. Let me know if I missed something important in my logic

[mastercoms]

@heisluft Is this still WIP or ready for review?

[heisluft]

I’m sorry, I kind of lost track of this PR. After loosing some of my work to faulty git usage of mine I lost motivation to actually finish this PR. There are still features to implement concerning the actual travel to the nether and I fear this PR is getting too big if I tried to mimic exact vanilla behavior.

Don’t get me wrong though, I will continue my work on this today in order to get it working, although it will be more of a quick and dirty hack as I would have to make changes to GlowKit and seemingly unrelated code making this PR too confusing and difficult to review.

I look, however, into making a follow-up PR to GlowKit and GlowStone fixing the shortcomings of my hacky implementation.

TL;DR: No, this PR is not yet ready for review, but I continue contributing and will request review as soon as I’m done

[heisluft]

Next (And probably last sneak peak).
I decided not to check wheter the bounding box of the portal block intersects the one of the player for now, so players get Teleported even if they technically are not standing in a portal. This has no other reason than not having enough time today.

EDIT: Done

[heisluft]

Finished Work on this PR, ready for review

[aramperes]

This is some great work! I was hoping for more unit tests though, or at least setting up the ground work by separating the calculations into readable units.

[aramperes]

Final stretch!

[mastercoms]

@aramperes What's left for this?