From fb93388f06fe87ee75aaaf04cf6edcf01a26d981 Mon Sep 17 00:00:00 2001
From: SmallJoker <mk939@ymail.com>
Date: Thu, 19 Jul 2018 14:36:21 +0200
Subject: [PATCH] Replace deprecated invsize[] with size[]

---
 manual.md |  165 +++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 149 insertions(+), 16 deletions(-)

diff --git a/manual.md b/manual.md
index 1b8f1ed..4ad01fc 100644
--- a/manual.md
+++ b/manual.md
@@ -179,10 +179,7 @@
 blocks, so several latex lumps can be extracted from a tree in one visit.
 
 Raw latex isn't used directly.  It must be vulcanized to produce finished
-rubber.  This can be performed by simply cooking the latex, with each
-latex lump producing one lump of rubber.  If you have an extractor,
-however, the latex is better processed there: each latex lump will
-produce three lumps of rubber.
+rubber.  This can be performed by alloying the latex with coal dust.
 
 ### metal ###
 
@@ -672,6 +669,142 @@
 in both locked and unlocked flavors.  All of the chests work with the
 pneumatic tubes of the pipeworks mod.
 
+radioactivity
+-------------
+
+The technic mod adds radioactivity to the game, as a hazard that can
+harm player characters.  Certain substances in the game are radioactive,
+and when placed as blocks in the game world will damage nearby players.
+Conversely, some substances attenuate radiation, and so can be used
+for shielding.  The radioactivity system is based on reality, but is
+not an attempt at serious simulation: like the rest of the game, it has
+many simplifications and deliberate deviations from reality in the name
+of game balance.
+
+In real life radiological hazards can be roughly divided into three
+categories based on the time scale over which they act: prompt radiation
+damage (such as radiation burns) that takes effect immediately; radiation
+poisoning that becomes visible in hours and lasts weeks; and cumulative
+effects such as increased cancer risk that operate over decades.
+The game's version of radioactivity causes only prompt damage, not
+any delayed effects.  Damage comes in the abstracted form of removing
+the player's hit points, and is immediately visible to the player.
+As with all other kinds of damage in the game, the player can restore
+the hit points by eating food items.  High-nutrition foods, such as the
+pie baskets supplied by the bushes\_classic mod, are a useful tool in
+dealing with radiological hazards.
+
+Only a small range of items in the game are radioactive.  From the technic
+mod, the only radioactive items are uranium ore, refined uranium blocks,
+nuclear reactor cores (when operating), and the materials released when
+a nuclear reactor melts down.  Other mods can plug into the technic
+system to make their own block types radioactive.  Radioactive items
+are harmless when held in inventories.  They only cause radiation damage
+when placed as blocks in the game world.
+
+The rate at which damage is caused by a radioactive block depends on the
+distance between the source and the player.  Distance matters because the
+damaging radiation is emitted equally in all directions by the source,
+so with distance it spreads out, so less of it will strike a target
+of any specific size.  The amount of radiation absorbed by a target
+thus varies in proportion to the inverse square of the distance from
+the source.  The game imitates this aspect of real-life radioactivity,
+but with some simplifications.  While in real life the inverse square law
+is only really valid for sources and targets that are small relative to
+the distance between them, in the game it is applied even when the source
+and target are large and close together.  Specifically, the distance is
+measured from the center of the radioactive block to the abdomen of the
+player character.  For extremely close encounters, such as where the
+player swims in a radioactive liquid, there is an enforced lower limit
+on the effective distance.
+
+Different types of radioactive block emit different amounts of radiation.
+The least radioactive of the radioactive block types is uranium ore,
+which causes 0.25 HP/s damage to a player 1 m away.  A block of refined
+but unenriched uranium, as an example, is nine times as radioactive,
+and so will cause 2.25 HP/s damage to a player 1 m away.  By the inverse
+square law, the damage caused by that uranium block reduces by a factor
+of four at twice the distance, that is to 0.5625 HP/s at a distance of 2
+m, or by a factor of nine at three times the distance, that is to 0.25
+HP/s at a distance of 3 m.  Other radioactive block types are far more
+radioactive than these: the most radioactive of all, the result of a
+nuclear reactor melting down, is 1024 times as radioactive as uranium ore.
+
+Uranium blocks are radioactive to varying degrees depending on their
+isotopic composition.  An isotope being fissile, and thus good as
+reactor fuel, is essentially uncorrelated with it being radioactive.
+The fissile U-235 is about six times as radioactive than the non-fissile
+U-238 that makes up the bulk of natural uranium, so one might expect that
+enriching from 0.7% fissile to 3.5% fissile (or depleting to 0.0%) would
+only change the radioactivity of uranium by a few percent.  But actually
+the radioactivity of enriched uranium is dominated by the non-fissile
+U-234, which makes up only about 50 parts per million of natural uranium
+but is about 19000 times more radioactive than U-238.  The radioactivity
+of natural uranium comes just about half from U-238 and half from U-234,
+and the uranium gets enriched in U-234 along with the U-235.  This makes
+3.5%-fissile uranium about three times as radioactive as natural uranium,
+and 0.0%-fissile uranium about half as radioactive as natural uranium.
+
+Radiation is attenuated by the shielding effect of material along the
+path between the radioactive block and the player.  In general, only
+blocks of homogeneous material contribute to the shielding effect: for
+example, a block of solid metal has a shielding effect, but a machine
+does not, even though the machine's ingredients include a metal case.
+The shielding effect of each block type is based on the real-life
+resistance of the material to ionising radiation, but for game balance
+the effectiveness of shielding is scaled down from real life, more so
+for stronger shield materials than for weaker ones.  Also, whereas in
+real life materials have different shielding effects against different
+types of radiation, the game only has one type of damaging radiation,
+and so only one set of shielding values.
+
+Almost any solid or liquid homogeneous material has some shielding value.
+At the low end of the scale, 5 meters of wooden planks nearly halves
+radiation, though in that case the planks probably contribute more
+to safety by forcing the player to stay 5 m further away from the
+source than by actual attenuation.  Dirt halves radiation in 2.4 m,
+and stone in 1.7 m.  When a shield must be deliberately constructed,
+the preferred materials are metals, the denser the better.  Iron and
+steel halve radiation in 1.1 m, copper in 1.0 m, and silver in 0.95 m.
+Lead would halve in 0.69 m (its in-game shielding value is 80).  Gold halves radiation
+in 0.53 m (factor of 3.7 per meter), but is a bit scarce to use for
+this purpose.  Uranium halves radiation in 0.31 m (factor of 9.4 per
+meter), but is itself radioactive.  The very best shielding in the game
+is nyancat material (nyancats and their rainbow blocks), which halves
+radiation in 0.22 m (factor of 24 per meter), but is extremely scarce. See [technic/technic/radiation.lua](https://github.com/minetest-technic/technic/blob/master/technic/radiation.lua) for the in-game shielding values, which are different from real-life values.
+
+If the theoretical radiation damage from a particular source is
+sufficiently small, due to distance and shielding, then no damage at all
+will actually occur.  This means that for any particular radiation source
+and shielding arrangement there is a safe distance to which a player can
+approach without harm.  The safe distance is where the radiation damage
+would theoretically be 0.25 HP/s.  This damage threshold is applied
+separately for each radiation source, so to be safe in a multi-source
+situation it is only necessary to be safe from each source individually.
+
+The best way to use uranium as shielding is in a two-layer structure,
+of uranium and some non-radioactive material.  The uranium layer should
+be nearer to the primary radiation source and the non-radioactive layer
+nearer to the player.  The uranium provides a great deal of shielding
+against the primary source, and the other material shields against
+the uranium layer.  Due to the damage threshold mechanism, a meter of
+dirt is sufficient to shield fully against a layer of fully-depleted
+(0.0%-fissile) uranium.  Obviously this is only worthwhile when the
+primary radiation source is more radioactive than a uranium block.
+
+When constructing permanent radiation shielding, it is necessary to
+pay attention to the geometry of the structure, and particularly to any
+holes that have to be made in the shielding, for example to accommodate
+power cables.  Any hole that is aligned with the radiation source makes a
+"shine path" through which a player may be irradiated when also aligned.
+Shine paths can be avoided by using bent paths for cables, passing
+through unaligned holes in multiple shield layers.  If the desired
+shielding effect depends on multiple layers, a hole in one layer still
+produces a partial shine path, along which the shielding is reduced,
+so the positioning of holes in each layer must still be considered.
+Tricky shine paths can also be addressed by just keeping players out of
+the dangerous area.
+
 electrical power
 ----------------
 
@@ -828,7 +961,8 @@
 energy to let an electrical network cope with mismatched supply and
 demand.  They have a secondary purpose of charging and discharging
 powered tools.  They are thus a mixture of electrical infrastructure,
-powered machine, and generator.
+powered machine, and generator.  Battery boxes connect to cables only
+from the bottom.
 
 MV and HV battery boxes have upgrade slots.  Energy upgrades increase
 the capacity of a battery box, each by 10% of the un-upgraded capacity.
@@ -843,10 +977,10 @@
 infrastructure of that tier, just to get access to faster charging.
 
 MV and HV battery boxes work with pneumatic tubes.  An item can be input
-to the charging slot through the bottom of the battery box, or to the
-discharging slot through the top.  Items are not accepted through the
-front, back, or sides.  With a tube upgrade, fully charged/discharged
-tools (as appropriate for their slot) will be ejected through a side.
+to the charging slot through the sides or back of the battery box, or
+to the discharging slot through the top.  With a tube upgrade, fully
+charged/discharged tools (as appropriate for their slot) will be ejected
+through a side.
 
 ### processing machines ###
 
@@ -1110,12 +1244,12 @@
 
 ### hydro generator ###
 
-The hydro generator is an LV power generator that generates a small amount
-of power from the natural motion of water.  To operate, the generator must
-be horizontally adjacent to water.  It doesn't matter whether the water
-consists of source blocks or flowing blocks.  Having water adjacent on
-more than one side, up to the full four, increases the generator's output.
-The water itself is unaffected by the generator.
+The hydro generator is an LV power generator that generates a respectable
+amount of power from the natural motion of water.  To operate, the
+generator must be horizontally adjacent to flowing water.  The power
+produced is dependent on how much flow there is across any or all four
+sides, the most flow of course coming from water that's flowing straight
+down.
 
 ### geothermal generator ###
 
@@ -1349,6 +1483,5 @@
     *   sonic screwdriver
 *   liquid cans
 *   wrench
-*   radioactivity
 *   frames
 *   templates

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