A very jank circle algorithm that overdraws many of the lines but mostly works.

assets/config.json

@@ -5,7 +5,7 @@
     "PLAYER_TILE": "\ua66b",
     "ENEMY_TILE": "\u1d5c",
     "BG_TILE": "█",
-    "WATER_TILE": "\u26c6"
+    "WATER_TILE": "\u224b"
   },
   "enemy": {
     "HEARING_DISTANCE": 8

matrix.cpp

@@ -179,6 +179,58 @@ namespace matrix {
     }
   }
 
+
+  circle::circle(Point center, int radius) :
+    center(center), radius(radius)
+  {
+    xi = 0;
+    yi = radius;
+    m = 5 - 4 * radius;
+    step = 0;
+  }
+
+  void circle::update() {
+    if(m > 0) {
+      yi--;
+      m -= 8 * yi;
+    }
+    xi++;
+    m += 8 * xi + 4;
+  }
+
+  bool circle::next() {
+    if(xi <= yi) {
+      switch(step % 4) {
+        case 0:
+          x0 = center.x - xi;
+          y = center.y - yi;
+          x1 = center.x + xi;
+          break;
+        case 1:
+          x0 = center.x - yi;
+          y = center.y - xi;
+          x1 = center.x + yi;
+          break;
+        case 2:
+          x0 = center.x - yi;
+          y = center.y + xi;
+          x1 = center.x + yi;
+          break;
+        case 3:
+          x0 = center.x - xi;
+          y = center.y + yi;
+          x1 = center.x + xi;
+          update();
+          break;
+      }
+
+      step++;
+      return true;
+    } else {
+      return false;
+    }
+  }
+
   void dump(const std::string &msg, Matrix &map, int show_x, int show_y) {
     println("----------------- {}", msg);
 

matrix.hpp

@@ -108,4 +108,20 @@ namespace matrix {
     line(Point start, Point end);
     bool next();
   };
+
+  struct circle {
+    Point center;
+    int radius = 0;
+    int xi = 0;
+    int yi = 0;
+    int m = 0;
+    int step = 0;
+    int x0;
+    int x1;
+    int y;
+
+    circle(Point center, int radius);
+    void update();
+    bool next();
+  };
 }

status.txt

@@ -5,23 +5,18 @@ TODAY'S GOAL:
 * Flame pillars icon \u2e3e
 * Room should always be found.
 
-* Change the test matrix to be irregular dimensions.
 * Study https://github.com/hirdrac/gx_lib/blob/main/gx/Unicode.hh
 * Study this https://en.cppreference.com/w/cpp/language/explicit
 * Study https://en.cppreference.com/w/cpp/language/member_functions#Special_member_functions
 
-* Light should flood using the dijkstra map rather than use a box.
-
 -1. Learn std::initializer_list by using it.
 0. \ua3fd causes the character immediately after to vanish. Make a test and solve it.
 1. Why do Sliders only have to be kept around forever and can't go in containers like everything else?
 
-* Make a for-loop generator thing, and figure out whatever this magic matrix-processing-without-for-loops tech is (that probably doesn't exist).
-
-"you could make an iterator type that you create with the Matrix & a box - then it iterates though each row/column and updates its x/y values. More code over all but loops like you're doing now could be simpler"
-
 TODO:
 
+* Add a char lookup input to the designer.
+
 * Make the light directional.
 
 * Hot key for debug view.

tests/matrix.cpp

@@ -224,3 +224,25 @@ TEST_CASE("prototype line algorithm", "[matrix:line]") {
     REQUIRE(f_found);
   }
 }
+
+TEST_CASE("prototype circle algorithm", "[matrix:circle]") {
+  size_t width = Random::uniform<size_t>(10, 13);
+  size_t height = Random::uniform<size_t>(10, 15);
+  Map map(width,height);
+  // create a target for the paths
+  Point start{.x=map.width() / 2, .y=map.height()/2};
+
+  for(int radius = 2; radius < 5; radius++) {
+    // use an empty map
+    Matrix result = map.walls();
+
+    for(matrix::circle it{start, radius}; it.next();) {
+      println("y={}, x0={}, x1={}", it.y, it.x0, it.x1);
+      for(int i = it.x0; i < it.x1; i++) {
+        result[it.y][i] += 1;
+      }
+    }
+
+    matrix::dump("RESULT AFTER CIRCLE", result, start.x, start.y);
+  }
+}