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 EOFÿ