SOTN/RNG - Revision history

SestrenExsis: Minor edit

2024-05-30T02:55:51Z

Minor edit

SestrenExsis: Fix return value of Evil RNG

2024-03-27T20:29:42Z

Fix return value of Evil RNG

SestrenExsis: Fix bug in Evil RNG, verified by consulting PSX documentation

2024-03-19T03:13:59Z

Fix bug in Evil RNG, verified by consulting PSX documentation

SestrenExsis: Reference Saturn's Evil RNG

2024-01-23T03:03:43Z

Reference Saturn's Evil RNG

SestrenExsis: Add link to Medusa Head

2023-11-17T23:00:55Z

Add link to Medusa Head

SestrenExsis: Minor edit

2023-11-17T22:53:38Z

Minor edit

SestrenExsis: Minor edit

2023-06-20T00:12:45Z

Minor edit

SestrenExsis: Document the Nice and Evil RNG

2023-06-19T12:24:15Z

Document the Nice and Evil RNG

SestrenExsis: SestrenExsis moved page SOTN/Nice RNG to SOTN/RNG: No need to split RNG up into two pages

2023-06-14T10:14:42Z

SestrenExsis moved page SOTN/Nice RNG to SOTN/RNG: No need to split RNG up into two pages

SestrenExsis: Create Nice RNG page

2023-06-13T11:45:08Z

Create Nice RNG page

New page

Symphony of the Night uses Pseudo-Random Number Generators when randomness is needed in the game. There are two PRNGs that are currently known about (dubbed Nice and Evil), and each is responsible for handling the randomness of different events in the game.

Both PRNGs operate in a similar fashion, but have different numbers used when determining the next seed value. The Nice RNG is responsible for, among other things, determining the location of Dracula's teleports in the Prologue, determining [[SOTN/Flea_Man|Flea Man]] jumps, and ...

TODO: Flesh out this page

@@ Line 1: / Line 1: @@
 Symphony of the Night uses [https://en.wikipedia.org/wiki/Pseudorandom_number_generator| Pseudo-Random Number Generators] when randomness is needed in the game. There are two PRNGs that are currently known about (dubbed Nice and Evil), and each is responsible for handling the randomness of different events in the game.
-Both RNGs are set to an initial value of 0 on startup (NOTE: On Saturn the initial value for the Evil RNG is actually 1 instead of 0). For the most part, the Evil RNG is advanced once every frame, even if the player isn't doing anything (hence why it has been dubbed Evil). Different functions within the games code will also make specific calls to the Nice and Evil RNG, and so different events will trigger one or the other. A comprehensive list of what events call which RNG is not known, but a few events have been figured out. The Nice RNG is responsible for determining the location of Dracula's teleports in the Prologue, determining [[SOTN/Flea_Man|Flea Man]] jumps, determining the rotations of the Books in the Library, etc. The Evil RNG is responsible for determining whether or not an item drop occurs after an enemy dies and whether or not an item drop will be rare, uncommon, or common. The Evil RNG is also responsible for determining which Food item will drop from a Meal Ticket.
+Both RNGs are set to an initial value of 0 on startup (NOTE: On Saturn the initial value for the Evil RNG is actually 1 instead of 0). For the most part, the Evil RNG is advanced once every frame, even if the player isn't doing anything (hence why it has been dubbed Evil). Different functions within the game's code will also make specific calls to the Nice and Evil RNG, and so different events will trigger one or the other. A comprehensive list of what events call which RNG is not known, but a few events have been figured out. The Nice RNG is responsible for determining the location of Dracula's teleports in the Prologue, determining [[SOTN/Flea_Man|Flea Man]] jumps, determining the rotations of the Books in the Library, etc. The Evil RNG is responsible for determining whether or not an item drop occurs after an enemy dies and whether or not an item drop will be rare, uncommon, or common. The Evil RNG is also responsible for determining which Food item will drop from a Meal Ticket.
 Some events in the game are the result of calls to both, as in the case of [[SOTN/Medusa_Head|Medusa Head]] spawn behavior.

@@ Line 27: / Line 27: @@
      def current(self) -> int:
-         result = self.seed >> 0x10
+         result = 0x7FFF & (self.seed >> 0x10)
          return result

@@ Line 27: / Line 27: @@
      def current(self) -> int:
-         result = self.seed >> 0x11
+         result = self.seed >> 0x10
          return result

@@ Line 1: / Line 1: @@
 Symphony of the Night uses [https://en.wikipedia.org/wiki/Pseudorandom_number_generator| Pseudo-Random Number Generators] when randomness is needed in the game. There are two PRNGs that are currently known about (dubbed Nice and Evil), and each is responsible for handling the randomness of different events in the game.
-Both RNGs are set to an initial value of 0 on startup. For the most part, the Evil RNG is advanced once every frame, even if the player isn't doing anything (hence why it has been dubbed Evil). Different functions within the games code will also make specific calls to the Nice and Evil RNG, and so different events will trigger one or the other. A comprehensive list of what events call which RNG is not known, but a few events have been figured out. The Nice RNG is responsible for determining the location of Dracula's teleports in the Prologue, determining [[SOTN/Flea_Man|Flea Man]] jumps, determining the rotations of the Books in the Library, etc. The Evil RNG is responsible for determining whether or not an item drop occurs after an enemy dies and whether or not an item drop will be rare, uncommon, or common. The Evil RNG is also responsible for determining which Food item will drop from a Meal Ticket.
+Both RNGs are set to an initial value of 0 on startup (NOTE: On Saturn the initial value for the Evil RNG is actually 1 instead of 0). For the most part, the Evil RNG is advanced once every frame, even if the player isn't doing anything (hence why it has been dubbed Evil). Different functions within the games code will also make specific calls to the Nice and Evil RNG, and so different events will trigger one or the other. A comprehensive list of what events call which RNG is not known, but a few events have been figured out. The Nice RNG is responsible for determining the location of Dracula's teleports in the Prologue, determining [[SOTN/Flea_Man|Flea Man]] jumps, determining the rotations of the Books in the Library, etc. The Evil RNG is responsible for determining whether or not an item drop occurs after an enemy dies and whether or not an item drop will be rare, uncommon, or common. The Evil RNG is also responsible for determining which Food item will drop from a Meal Ticket.
 Some events in the game are the result of calls to both, as in the case of [[SOTN/Medusa_Head|Medusa Head]] spawn behavior.

← Older revision		Revision as of 23:00, 17 November 2023
Line 2:		Line 2:

	Both RNGs are set to an initial value of 0 on startup. For the most part, the Evil RNG is advanced once every frame, even if the player isn't doing anything (hence why it has been dubbed Evil). Different functions within the games code will also make specific calls to the Nice and Evil RNG, and so different events will trigger one or the other. A comprehensive list of what events call which RNG is not known, but a few events have been figured out. The Nice RNG is responsible for determining the location of Dracula's teleports in the Prologue, determining [[SOTN/Flea_Man\|Flea Man]] jumps, determining the rotations of the Books in the Library, etc. The Evil RNG is responsible for determining whether or not an item drop occurs after an enemy dies and whether or not an item drop will be rare, uncommon, or common. The Evil RNG is also responsible for determining which Food item will drop from a Meal Ticket.		Both RNGs are set to an initial value of 0 on startup. For the most part, the Evil RNG is advanced once every frame, even if the player isn't doing anything (hence why it has been dubbed Evil). Different functions within the games code will also make specific calls to the Nice and Evil RNG, and so different events will trigger one or the other. A comprehensive list of what events call which RNG is not known, but a few events have been figured out. The Nice RNG is responsible for determining the location of Dracula's teleports in the Prologue, determining [[SOTN/Flea_Man\|Flea Man]] jumps, determining the rotations of the Books in the Library, etc. The Evil RNG is responsible for determining whether or not an item drop occurs after an enemy dies and whether or not an item drop will be rare, uncommon, or common. The Evil RNG is also responsible for determining which Food item will drop from a Meal Ticket.
		+
		+	Some events in the game are the result of calls to both, as in the case of [[SOTN/Medusa_Head\|Medusa Head]] spawn behavior.

	Both RNGs operate in a similar manner, but use different numbers as their multiplier, increment, and shift, as detailed in the code sections at the bottom of the page.		Both RNGs operate in a similar manner, but use different numbers as their multiplier, increment, and shift, as detailed in the code sections at the bottom of the page.

@@ Line 19: / Line 19: @@
          return result</nowiki>
-  <nowiki># Python implementation of the evil RNG used in SOTN
+  <nowiki># Python implementation of the Evil RNG used in SOTN
 class EvilRng():
      def __init__(self, initial_seed: int=0):

@@ Line 1: / Line 1: @@
-Symphony of the Night uses Pseudo-Random Number Generators when randomness is needed in the game. There are two PRNGs that are currently known about (dubbed Nice and Evil), and each is responsible for handling the randomness of different events in the game.
+Symphony of the Night uses [https://en.wikipedia.org/wiki/Pseudorandom_number_generator| Pseudo-Random Number Generators] when randomness is needed in the game. There are two PRNGs that are currently known about (dubbed Nice and Evil), and each is responsible for handling the randomness of different events in the game.
-Both PRNGs operate in a similar fashion, but have different numbers used when determining the next seed value. The Nice RNG is responsible for, among other things, determining the location of Dracula's teleports in the Prologue, determining [[SOTN/Flea_Man|Flea Man]] jumps, and ...
+Both RNGs are set to an initial value of 0 on startup. For the most part, the Evil RNG is advanced once every frame, even if the character isn't doing anything (hence why it has been dubbed Evil). Different functions within the games code will also make specific calls to the Nice and Evil RNG, and so different events will trigger one or the other. A comprehensive list of what events call which RNG is not known, but a few events have been figured out. The Nice RNG is responsible for determining the location of Dracula's teleports in the Prologue, determining [[SOTN/Flea_Man|Flea Man]] jumps, determining the rotations of the Books in the Library, etc. The Evil RNG is responsible for determining whether or not an item drop occurs after an enemy dies and whether or not an item drop will be rare, uncommon, or common. The Evil RNG is also responsible for determining which Food item will drop from a Meal Ticket.
-TODO: Flesh out this page
+Both RNGs operate in a similar manner, but use different numbers as their multiplier, increment, and shift, as detailed in the code sections at the bottom of the page.

← Older revision	Revision as of 10:14, 14 June 2023
(No difference)