Dragon's Lair (NES)/Game Mechanics(ntscu) - Revision history

Ktwo: /* Singe */

2023-09-15T11:10:54Z

‎Singe

Ktwo: /* Singe */

2023-08-12T16:23:13Z

‎Singe

Ktwo: /* RNG */

2023-08-12T09:52:22Z

‎RNG

Ktwo: /* RNG */

2023-08-12T09:13:23Z

‎RNG

Ktwo: /* Bubbles */

2023-08-08T20:50:55Z

‎Bubbles

Ktwo: /* RNG */

2023-08-08T20:46:13Z

‎RNG

Ktwo: /* Energy */

2023-08-08T20:41:44Z

‎Energy

Ktwo: /* RNG */

2023-08-08T06:03:29Z

‎RNG

Ktwo: /* RNG */

2023-08-08T06:02:21Z

‎RNG

Ktwo: /* RNG */

2023-08-07T13:12:44Z

‎RNG

@@ Line 184: / Line 184: @@
 ===Singe===
 [[File:DL_Singe.PNG|50px]]<br />
-Singe's puffs are blown every 145 frames, but their height is based on RNG. The branch operator in $A26F determines if the puff will be high or low, based on if the accumulator (which will have the same value as $6A1) is even (low) or uneven (high). Because of the [[Dragon%27s_Lair_(NES)/Game_Mechanics(ntscu)#RNG|RNG]]'s shortcomings in this game, it's possible to slightly manipulate the puffs. For more detailed comments on what can realistically be controlled in a real-timee, see the routing section.
+Singe's puffs are blown every 145 frames, but their height is based on RNG. The branch operator in $A26F determines if the puff will be high or low, based on if the accumulator (which will have the same value as $6A1) is even (low) or uneven (high). Because of the [[Dragon%27s_Lair_(NES)/Game_Mechanics(ntscu)#RNG|RNG]]'s shortcomings in this game, it's possible to slightly manipulate the puffs. For more detailed comments on what can realistically be controlled in a real-time, see the routing section.
 <br />

@@ Line 184: / Line 184: @@
 ===Singe===
 [[File:DL_Singe.PNG|50px]]<br />
-Singe's puffs are blown every 145 frames, but their height is based on RNG. The branch operator in $A26F determines if the puff will be high or low, based on if the accumulator (which will have the same value as $6A1) is even (low) or uneven (high). Because of the [[Dragon%27s_Lair_(NES)/Game_Mechanics(ntscu)#RNG|RNG's]] shortcomings in this game, it's possible to slightly manipulate the puffs. For more detailed comments on what can realistically be controlled in a real-timee, see the routing section.
+Singe's puffs are blown every 145 frames, but their height is based on RNG. The branch operator in $A26F determines if the puff will be high or low, based on if the accumulator (which will have the same value as $6A1) is even (low) or uneven (high). Because of the [[Dragon%27s_Lair_(NES)/Game_Mechanics(ntscu)#RNG|RNG]]'s shortcomings in this game, it's possible to slightly manipulate the puffs. For more detailed comments on what can realistically be controlled in a real-timee, see the routing section.
 <br />

@@ Line 103: / Line 103: @@
 ==RNG==
-This game has two RNG-addresses, $6A1 and $6A2. The calculation to update these addresses starts at instruction $C000. Input to the calculation is the previous set of RNG-addresses and if the carry is set or not. Every frame (and not just every game frame!), including screen transitions and when loading bosses, the RNG sub-routine is called. The carry is set if R is pressed (or held down), except during screen transitions and when loading bosses (the inputs are not polled during these periods). Pressing R enters the calculation through setting the carry flag. The reason for R being special is because it's read as the last input from $4016 (the address sending the controller inputs). The other buttons do set the carry in the same way, but it's then cleared and only when the carry is set by R will it impact the RNG-calculation.<br /><br />
+This game has two RNG-addresses, $6A1 and $6A2. The calculation to update these addresses starts at instruction $C000. Input to the calculation is the previous set of RNG-addresses and if the carry is set or not. Every frame (and not just every game frame!), including screen transitions and when loading bosses, the RNG sub-routine is called. The carry is set if R is pressed (or held down). Pressing R enters the calculation through setting the carry flag. The reason for R being special is because it's read as the last input from $4016 (the address sending the controller inputs). The other buttons do set the carry in the same way, but it's then cleared and only when the carry is set by R will it impact the RNG-calculation.<br /><br />
 The following is a list of events that are controlled by the game's RNG and trigger additional call(s) to the RNG sub-routine (note that the carry always seems to be set when making these calls):

@@ Line 103: / Line 103: @@
 ==RNG==
-This game has two RNG-addresses, $6A1 and $6A2. The calculation to update these addresses starts at instruction $C000 and is called every frame (and not just every game frame!), including screen transitions and when loading bosses. Input to the calculation is the previous set of RNG-addresses and if R is pressed (or held down). Pressing R enters the calculation through setting the carry flag. The reason for R being special is because it's read as the last input from $4016 (the address sending the controller inputs). The other buttons do set the carry in the same way, but it's then cleared and only when the carry is set by R will it impact the RNG-calculation.<br /><br />
+This game has two RNG-addresses, $6A1 and $6A2. The calculation to update these addresses starts at instruction $C000. Input to the calculation is the previous set of RNG-addresses and if the carry is set or not. Every frame (and not just every game frame!), including screen transitions and when loading bosses, the RNG sub-routine is called. The carry is set if R is pressed (or held down), except during screen transitions and when loading bosses (the inputs are not polled during these periods). Pressing R enters the calculation through setting the carry flag. The reason for R being special is because it's read as the last input from $4016 (the address sending the controller inputs). The other buttons do set the carry in the same way, but it's then cleared and only when the carry is set by R will it impact the RNG-calculation.<br /><br />
 The following is a list of events that are controlled by the game's RNG and trigger additional call(s) to the RNG sub-routine (note that the carry always seems to be set when making these calls):
-* Checking for the Lizard King
+* Checking for the Lizard King (every game frame, for the sections that the LK can appear in)
 * Whether a bat is red or gray in level 2
 * Calculate a new direction for the Grim Reaper to point its finger in
@@ Line 147: / Line 147: @@
 [[File:DL_CL_to_NCL.PNG|400px]]<br /><br />
-An observation at this stage is that only the three first loops in each case are realistically accessible. One can theoretically access the other loops by repeatedly pressing (but not holding) R, which will prevent the RNG from ending up in one of the first three loops. This brings us to the next question. How long does it take to jump between loops? The following graphs show how many frames it takes to jump from an NCL to a CL (and vice versa). Note that only loops 1-3 were used in this simulation (and have been aggregated), since the other loops are in practice inaccessible.<br /><br />
+An observation at this stage is that only the three first loops in each case are realistically accessible. One can theoretically access the other loops by repeatedly pressing (but not holding) R, which will prevent the RNG from ending up in one of the first three loops. However, this is unlikely to carry any importance when playing in real-time. It's also worth noting that NCL2 is more than 6 times more common "than it should be". With only 4 pairs in NCL2 and 201 in total for NCL1-3, one would have expected roughly 2% ending up in this loop and not the ~13%. This will likely be a cause for skewing the probabilities of RNG-dependent events. <br /><br />
 [[File:Time_to_CL.PNG|600px]] [[File:Time_to_NCL.PNG|580px]]<br /><br />

@@ Line 187: / Line 187: @@
 ===Bubbles===
 [[File:DL_Bubble.PNG|50px]]<br />
-* 6A6/6A7 - primary/secondary bubble timer
+* $6A6/$6A7 - primary/secondary bubble timer
-* 4A - reference address for bubble duration
+* $4A - reference address for bubble duration
-Bubbles spawn according to the timer in 6A6 (and 6A7, which is used when necessary). The timer is local and triggered by Dirk getting close enough (in the x-direction) to its spawn point. The timer is set from a look-up table with three different values that cycle. The game uses the value in $4A as reference address for cycling through the values.
+Bubbles spawn according to the timer in $6A6 (and $6A7, which is used when necessary). The timer is local and triggered by Dirk getting close enough (in the x-direction) to its spawn point. The timer is set from a look-up table with three different values that cycle. The game uses the value in $4A as reference address for cycling through the values.
 <br />

@@ Line 126: / Line 126: @@
 <br />
-When running simulations of the RNG-calculation, the RNG-addresses fairly quickly get stuck in a loop. This is true for all 65536 (256^2) pairs of possible start values. When the RNG-calculation runs without a carry at the start (so R not being pressed and no events triggering additional RNG-calls), there are 4 possible RNG-loops. They will be referred to as NCL1-NCL4 (No-Carry Loop):
+When running simulations of the RNG-calculation, the RNG-addresses quickly get stuck in a loop. This is true for all 65536 (256^2) pairs of possible start values. When the RNG-calculation runs without a carry at the start (so R not being pressed and no events triggering additional RNG-calls), there are 4 possible RNG-loops. They will be referred to as NCL1-NCL4 (No-Carry Loop):
 * NCL1 - 160 pairs in total, one element being $6A1 = 0x13, $6A2 = 0x6D
 * NCL2 - 4 pairs in total, one element being $6A1 = 0x27, $6A2 = 0x89

@@ Line 99: / Line 99: @@
 * If an E is collected when player energy > 23, you'll end up with 39 BE and whatever you had left of small energy.
 <br />
 Note: There is a bug that can occur with the Lizard King. If you bump into him in the vicinity of where the first serpent was supposed to appear, you'll take damage continuously. In a speedrun setting (so walking to the right without stopping), that means a damage of 12 BE. If you stop moving while taking damage, even more energy will be lost.<br /><br />
 ==RNG==

@@ Line 143: / Line 143: @@
 [[File:DL_NCL_to_CL.PNG|400px]]<br /><br />
-The corresponding chart when jumping from a CL to an NCL looks like this:<br />
+The corresponding chart when jumping from a CL to an NCL:<br />
 [[File:DL_CL_to_NCL.PNG|400px]]<br /><br />

@@ Line 105: / Line 105: @@
 The following is a list of events that are controlled by the game's RNG and trigger additional call(s) to the RNG sub-routine (note that the carry always seems to be set when making these calls):
-* The appearance of the Lizard King
+* Checking for the Lizard King
 * Whether a bat is red or gray in level 2
-* The direction the Grim Reaper points its finger
+* Calculate a new direction for the Grim Reaper to point its finger in
 * Singe's smoke puffs (high or low)
 <br />
@@ Line 126: / Line 126: @@
 When running simulations of the RNG-calculation, the RNG-addresses fairly quickly get stuck in a loop. This is true for all 65536 (256^2) pairs of possible start values. When the RNG-calculation runs without a carry at the start (so R not being pressed and no events triggering additional RNG-calls), there are 4 possible RNG-loops. They will be referred to as NCL1-NCL4 (No-Carry Loop):
-* NCL1 - 160 pairs in total with the first element being $6A1 = 0x13, $6A2 = 0x6D
+* NCL1 - 160 pairs in total, one element being $6A1 = 0x13, $6A2 = 0x6D
-* NCL2 - 4 pairs in total with the first element being $6A1 = 0x27, $6A2 = 0x89
+* NCL2 - 4 pairs in total, one element being $6A1 = 0x27, $6A2 = 0x89
-* NCL3 - 37 pairs in total with the first element being $6A1 = 0x28, $6A2 = 0xA0
+* NCL3 - 37 pairs in total, one element being $6A1 = 0x28, $6A2 = 0xA0
 * NCL4 - 1 pair in total ($6A1 = 0xAE, $6A2 = 0x24)
 <br />
 When the RNG-calculation runs with the carry set at the start (so R being held down), there are 5 possible RNG-loops. These will be referred to as CL1-CL5 (Carry Loop):
-* CL1 - 95 pairs in total with the first element being $6A1 = 0x00, $6A2 = 0xE4
+* CL1 - 95 pairs in total, one element being $6A1 = 0x00, $6A2 = 0xE4
-* CL2 - 150 pairs in total with the first element being $6A1 = 0x00, $6A2 = 0x4E
+* CL2 - 150 pairs in total, one element being $6A1 = 0x00, $6A2 = 0x4E
-* CL3 - 55 pairs in total with the first element being $6A1 = 0x13, $6A2 = 0x6D
+* CL3 - 55 pairs in total, one element being $6A1 = 0x13, $6A2 = 0x6D
 * CL4 - 1 pair in total ($6A1 = 0xAD, $6A2 = 0x23)
-* CL5 - 4 pairs in total with the first element being $6A1 = 0x26, $6A2 = 0x89
+* CL5 - 4 pairs in total, one element being $6A1 = 0x26, $6A2 = 0x89
 <br />
-When the RNG is in one of the NCL and R is pressed (and held down), the RNG will eventually jump to one of the CL loops. The following chart shows the probabilities of jumping from an NCL to a CL:<br />
+When the RNG is in one of the NCL and R is pressed (and held down), the RNG will eventually jump to somewhere in one of the CL loops. The following chart shows the probabilities of jumping from an NCL to a CL:<br />
 [[File:DL_NCL_to_CL.PNG|400px]]<br /><br />
@@ Line 146: / Line 146: @@
 [[File:DL_CL_to_NCL.PNG|400px]]<br /><br />
-An observation at this stage is that only the three first loops in each case are realistically accessible. One can theoretically access the other loops by repeatedly pressing (but not holding) R, which will prevent the RNG from ending up in one of the loops. This brings us to the next question. How long does it take to jump between loops? The following graphs show how many frames it takes to jump from an NCL to a CL (and vice versa). Note that only loops 1-3 were used in this simulation (and have been aggregated), since the other loops are in practice inaccessible.<br /><br />
+An observation at this stage is that only the three first loops in each case are realistically accessible. One can theoretically access the other loops by repeatedly pressing (but not holding) R, which will prevent the RNG from ending up in one of the first three loops. This brings us to the next question. How long does it take to jump between loops? The following graphs show how many frames it takes to jump from an NCL to a CL (and vice versa). Note that only loops 1-3 were used in this simulation (and have been aggregated), since the other loops are in practice inaccessible.<br /><br />
 [[File:Time_to_CL.PNG|600px]] [[File:Time_to_NCL.PNG|580px]]<br /><br />