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[PATCH] Avoid calling the train collision all the time at the expense of memory #541

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DorpsGek opened this issue Jan 12, 2007 · 8 comments
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[PATCH] Avoid calling the train collision all the time at the expense of memory #541

DorpsGek opened this issue Jan 12, 2007 · 8 comments
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flyspray This issue is imported from FlySpray (https://bugs.openttd.org/) patch from FlySpray This issue is in fact a Patch, but imported from FlySrpay

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@DorpsGek
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madman2003 opened the ticket and wrote:

The beheaviour of this patch is fairly simple:

A TrackBits is stored of currently occupied segments is stored in the map, the first engine activates it, the last one removes it.

Once an already existing trackbit is activated again, a overload bit is activated, which will make trains actively check for collisions.

Once a vehicle leaves the tile or is destroyed, it is reset.

This modification requires a byte sized m7.

Under normal curcomstances the CheckTrainCollision() function is not called, testing suggest quite an improvement (60% vs 50% cpu usage on a map with 900-1000 trains).

What do you think?

Known/possible problems:

If a vehicle is at the beginning of a tile, another vehicle will have to actually enter the tile before it collides.

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Reported version: trunk
Operating system: All

This issue was imported from FlySpray: https://bugs.openttd.org/task/541
@DorpsGek
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Rubidium wrote:

You only need 6 bits for the trackbits, so you can move the bit you would add to m6 to m7. The two other bits are only flags for special cases.

Furthermore: this data needs to be stored in the savegame for the simple reason that it needs to be in-sync in multiplayer games, or you need to rebuild that data when loading a savegame, but then it is more complex to set the overflow bit as two vehicles on a tile might be from the same train, but they may not be. Also, have you thought about what happens when loading a savegame?

Then you might have the possibilities that trains can go through eachother for a short time.

(I have not yet tested the patch or so, only read it)

This comment was imported from FlySpray: https://bugs.openttd.org/task/541#comment822

@DorpsGek
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madman2003 wrote:

You were right about the savegame stuff, i fixed that (for new games), not sure about old ones.

This comment was imported from FlySpray: https://bugs.openttd.org/task/541#comment823

@DorpsGek
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madman2003 wrote:

Tunnel and bridge handling is not working right, trying to fix that.

This comment was imported from FlySpray: https://bugs.openttd.org/task/541#comment824

@DorpsGek
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madman2003 wrote:

This should be working better, moving the warning bit in to m7 remains.

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This comment was imported from FlySpray: https://bugs.openttd.org/task/541#comment825

@DorpsGek
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madman2003 wrote:

I meant, moving the warning bit in m6(bit2) to m7 remains.

This comment was imported from FlySpray: https://bugs.openttd.org/task/541#comment826

@DorpsGek
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madman2003 wrote:

After finding out that m7 has too much overhead (game gets slower, on the largest map there is a 10 MiB memory increase, due to padding bytes), i made a simpler version, which takes away the bulk of the collision checking.

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This comment was imported from FlySpray: https://bugs.openttd.org/task/541#comment827

@DorpsGek
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madman2003 wrote:

This task can be closed, as it's outdated.

This comment was imported from FlySpray: https://bugs.openttd.org/task/541#comment1305

@DorpsGek
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Rubidium closed the ticket.

Reason for closing: Out of date

Something else with the same (or even better) characteristics has been committed to trunk (r10111).

This comment was imported from FlySpray: https://bugs.openttd.org/task/541

@DorpsGek DorpsGek added flyspray This issue is imported from FlySpray (https://bugs.openttd.org/) Vehicles patch from FlySpray This issue is in fact a Patch, but imported from FlySrpay labels Apr 6, 2018
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