Simplify collision detection to avoid punching tunnels

[tyomitch]

Resolves #1

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
pong-wars	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Feb 8, 2024 11:07am

[fgregg]

this fixes the tunneling, but without the bounce changing, i think it loses a lot of the pong-ness

[tyomitch]

this fixes the tunneling, but without the bounce changing, i think it loses a lot of the pong-ness

To reintroduce speed/angle randomisation, you can locally revert 674e095 from main

[vnglst]

The code is definitely clearer, doing a long running test right to see if the balls ever get stuck.

[vnglst]

Could we have a more descriptive variable name for ci and cj?

[tyomitch]

Are checkI and checkJ OK?

[vnglst]

How about column and row for i and j and nextRow and nextColumn for ci and cj?

[schlagmichdoch]

I believe this does not work yet.

Collision speed off

While the squares are bound to a grid the balls are not, so the balls center are not always at the center of a square.
This collision algorithm effectively increases the speed of the ball during a collision.

Collision that works correctly:
A ball is 1dx away from a wall. in the next frame its 0dx away. In the next frame its -1dx away.

Collision that does not work correctly:
A ball is 0.3dx away from a wall. In the frame it should be -0.7dx away from the wall.

Collision as point

By evaluating the next column with Math.floor((x + dx) / SQUARE_SIZE) the ball is effectively only evaluated as a point (x, y) or circle with radius 0. This leads to collisions if the ball center is close to a square center. This could be resolved by adding the radius to the next column statement: Math.floor((x + dx + radius * Math.sign(dx)) / SQUARE_SIZE) [1].

Diagonal collisions

The collision function only checks for collisions in neighbors. If a ball approaches diagonally towards a corner the collision is not correct. [2][3]

[1]

[2]

[3]

[tyomitch]

The code is definitely clearer, doing a long running test right to see if the balls ever get stuck.

Any plans to adopt the simplified collision detection code?