Decoded: Rogue (1980) by Toy, Arnold, Wichman
DOS version (1983) by Mel Sibony and Jon Lane
Source file: MAZE.C
Beginner friendly, line-by-line code walkthrough by MaiZure
MAZE.C provides functions for drawing mazes. There may be an issue with this
file - some code seems dead or in an incomplete/transitionary state
Original code:
https://britzl.github.io/roguearchive/
Original code with line numbers
http://www.maizure.org/projects/decoded-rogue/MAZE_linenum.txt
1 COMMENT
2 COMMENT
3 COMMENT
4 COMMENT
5 COMMENT
6 COMMENT
7 BLANK
8 Include the game header
9 Include the console management header
10 Bring in the height of the map defined in MACH_DEP.C (22 or 23 lines)
11 BLANK
12 Define a limit to the size of the logical maze frontier to 100 nodes
13 BLANK
14 Define a macro for FRONTIER to be the character 'F'
15 Define a macro for NOTHING to be a space
16 BLANK
17 Declare compilation unit integers for various maze metric temporaries
18 Declare compilations unit intergers for boundary sizes
19 Declare pointers to frontier positions
20 BLANK
DRAW MAZE
21 Define draw maze with 1 argument
22 Argument 1 is a pointer to the room area that the maze is drawn over
23 BLOCK START - draw_maze, draws a maze by manipulating map data in place
24 Declare temporary integers for room positions
25 Declare two arrays for frontier values, one for x and one for y
26 Declare a counter for passages
27 Declare a coordinate pair used for map positions
28 BLANK
29 Point the y frontier array to the base of the local array y
30 Point the x frontier array to the base of the local array x
31 Initialize the max values to 0
32 Set the top y of the maze to the top of the room
33 If the top of the maze is 0...
34 Then boost it to 1...don't start on the exact top edge
35 Set the top x of maze to the left size of the room
36 COMMENT
37 COMMENT
38 COMMENT
39 COMMENT
40 Set our working y position to the top (not random as the comment claims)
41 Set our working x position to the left (not random)
42 Set the initial position to passages
43 Add neighboring positions to the frontier
44 COMMENT
45 COMMENT
46 COMMENT
47 COMMENT
48 While there is a frontier
49 BLOCK START - Add from frontier
50 Connect a random frontier element to the maze
51 Calculate the new frontier since the maze just changed
52 BLOCK END - Add from frontier
53 COMMENT
54 COMMENT
55 COMMENT
56 COMMENT
57 Set the room's max.x based on the passages drawn so far. Note that this
variable was the largest possible room size prior to this statement
58 Set the room's max.y based on the passages drawn so far
59 Being a loop
60 Define a coordinate array with four elements
61 The first element is a coordinate offset for up
62 The first element is a coordinate offset for right
63 The first element is a coordinate offset for down
64 The first element is a coordinate offset for left
65 End of coordinate array definition
66 Declare a coordinate pointer
67 Declare an integer
68 BLANK
69 Choose a random point in the room and store it in spos
70 Loop through the array 4 times..
71 Offset the action coordinates based on the above array.
72 If the new position is not off the map and is a passage...
73 Increment the page count (order is 1, 3, 7, 15, ...)
74 End offset loop
75 Redo the loop and set each set to a valid passage
76 Set the final point as a valid passage
77 BLOCK END - draw_maze
78 BLANK
NEW FRONTIER
Frontier grows in all cardinal directions starting two points away from the
input location
79 Define new_frontier with two arguments
80 Arguments are an x and y map point
81 BLOCK START - new_frontier, adds cardinal points to the frontier
82 Attempts to add the map point two spaces above the input
83 Attempts to add the map point two spaces below the input
84 Attempts to add the map point two spaces left of the input
85 Attempts to add the map point two spaces right of the input
86 BLOCK END - new_frontier
87 BLANK
ADD FRONTIER
A 'frontier' is a point that is a candidate to become a part of the maze but
hasn't been chosen yet. It borders at least one actual maze passage.
88 Defines add_frnt with with arguments
89 Both arguments form a coordinate within the map
90 BLOCK START - add_frnt, adds a point to the potential maze frontier
91 If debug mode is enabled (it's not)...
92 And if we already have the maximum number of frontier candidates...
93 Print an error message
94 End check for debug mode
95 If the point is in the maze and hasn't been assigned yet...
96 BLOCK START - add point to the frontier
97 Set the point as a frontier space
98 Add that point's x coordinate to the frontier tracking array
99 Add y coordinate to the fontier array and increment the array counter
100 BLOCK END - add point to the frontier
101 BLOCK END - add_frnt
102 BLANK
103 COMMENT
104 COMMENT
105 COMMENT
CONNECT FRONTIER
106 Define con_frnt wih no arguments
107 BLOCK START - con_frnt, connects a frontier point with the maze
108 Declare some local variables for the calculations
109 Declare an integer array to hold four possible connection directions
110 Declare and initialize count to zero. Also coordinate points
111 BLANK
112 BLANK
113 COMMENT
114 COMMENT
115 COMMENT
116 Choose a random index in to the frontier array
117 Grab the y position of the chosen frontier
118 Grab the x position of the chosen frontier
119 Copy the last frontier y point in the array to the now-used point
120 Copy the last x to the used x position. Decrement the array size.
121 BLANK
122 COMMENT
123 COMMENT
124 COMMENT
125 If the map point two above the frontier is a valid passage...
126 Add that choice to the possible selections and increment the counter
127 If the map point two below the frontier is a valid passage...
128 Add that choice to the possible selections and increment the counter
129 If the map point two to the left of the frontier is a valid passage...
130 Add that choice to the possible selections and increment the counter
131 If the map point two to the right of the frontier is a valid passage...
132 Add that choice to the possible selections and increment the counter
133 COMMENT
134 COMMENT
135 COMMENT
136 COMMENT
137 Randomize one of the valid directions. At least one is always valid
138 Make the frontier point a valid part of the maze
139 SWITCH on the chosen direction
140 BLOCK START - Switch on a direction
141 CASE up: set the change in y coordinate
142 CASE down: set the change in y coordinate
143 CASE left: set the change in x coordinate
144 CASE right: set the change in x coordinate
145 BLOCK END - Switch on a direction
146 Set the current y to the calculated delta coordinate
147 Set the current x to the calculated delta coordinate
148 Check that the chosen direction is part of the maze room...
149 And dig out the passage, connecting it to the main maze
150 BLOCK END - con_frnt
151 BLANK
FIND MAZE VALUE
152 Define maze_at with two arguments, an x/y coordinate pair
153 BLOCK START - maze_at, checks a point and returns true if it's a maze
154 If the pair is within the room and it's also a valid passage...
155 Return true
156 Otherwise...
157 Return false
158 BLOCK END - maze_at
159 BLANK
SET MAZE PASSAGE
160 Define splat with two arguments, an x and y coordinate
161 BLOCK START - splat, sets input point as a maze passage.
162 Set the map point as a passage
163 Update the point flags to be
164 If the input x is the largest in use so far...
165 Update the max x tracking variable
166 If the input y is the largest in use so far...
167 Update the max y tracking variable
168 BLOCK END - splat
169 BLANK
170 Set MAXY to be one third of the height of the screen from the top y
171 Set MAXX to be one third of the width of the screen from the top x
172 BLANK
CHECK MAZE BOUNDARIES
173 Define inrange with two arguments
174 Both arguments are a coordinate to check
175 BLOCK START - inrange, returns true if the input is within the room
176 Return a typical four corners check on the x, y pair and the boundary
177 BLOCK END - inrange
178 EOFя