Implement brick picking logic

[rozniak]

Next step is to implement the brick picking and placement logic. There are some rules on being able to pick bricks, along with which bricks are taken alongside the brick selected. Will need to play the game to do some testing to see what the rules might be.

I am also marking this as wait-submodule because picked bricks need to be rendered semi-transparent which is not yet supported by rzxe.

[rozniak]

Waiting on this particular issue: rozniak/rzxe#21

[rozniak]

Feature sorted in rzxe, this issue can now go ahead.

[rozniak]

@Aaronlcj I know you had brick picking in your fork... have you a gist or something on what the logic is? I've tried drafting some ideas about how it works, I'm just struggling to think of a good way to do it. The original game seems to know which direction you can pop brick off (indicated by mouse cursor).

I was thinking of building 'trees' of connected bricks but it seems quite complex, I dunno if perhaps I'm overthinking it...

[rozniak]

The plan is to develop this by creating a set of tests with expected outcomes and amending the code until all tests are met. I have constructed some cases which need to be tested to make sure the edge cases are covered.

Here are some cases:

• SImple bridge - top brick is a junction
  
• Simple stairs, first brick connected upwards and thus blocked from upwards connection
  
• Connected both on top of and underneath grey bricks
  
• Looped connections with/without gap
  
• Ledge connected at a single point with independent brick to the right - Junkbot blocking entire ledge and stem
  

My thought is to use a node based system to figure out which paths can be selected. The loop case is to test cyclic references.

[rozniak]

Here's another case:

[rozniak]

I have put together some logic just now for the brick picking - just writing up some unit tests to check how this performs against the above cases.

[rozniak]

First little unit test for checking the direction bricks can be disconnected in the first bridge case is now passing. On the way to writing tests for the other cases and getting this feature finished. 😁

[rozniak]

All tests are now passing for pickup!

The remainder:

• Need to implement a 'hand' - detach bricks from scene
• Write a method + tests for checking placement of the picked up bricks
• Once all done, implement into game itself - wire up input and rendering

[rozniak]

All brick picking logic is now sorted - it's now a matter of wiring up in game.

It's partially working, but needs tuning with the mouse - here's a little screenshot of moved bricks on the demo scene:

Things to fix:

• Need to cast screen/window coordinates into viewport space (to handle scaled window)
• Clip mouse input to scene within the visible section of the scene (do not send input updates if outside the visible region - but do update via deltaTime)
• Improve hit registration - currently based on exact cells which isn't helpful in isometric view, should select a range of cells that cover the size of a brick or something
• Click and drag to detach brings that can go either way isn't working yet

[rozniak]

Isometric view code still needs some work - there is a method MouseHitTest() that does a nice hit test based in the isometric view. I think this should be used in DetachAt and PlaceAt as the actual method used to pick up bricks instead of taking an exact grid cell.

Don't know whether to keep the grid cell option as well... or whether to just do this viewport based thing only. Will have a think about it.

EDIT:
This is needed by the way because it's not really feasible to work MouseHitTest() in alongside the current implementation based on grid cells without being bodge-y (since the x-offset thing is partially akin to mouse input as it is).