Circle adjusted to work better but now I think hirdrac was right that it's easier to just calculate a distance from center and use that to determine light levels rather than a whole dpath.

lights.cpp

@@ -7,7 +7,7 @@ using std::vector;
 namespace lighting {
 
   void LightRender::render_circle_light(LightSource source, Point at, PointList &has_light) {
-    for(matrix::circle it{$lightmap, at, source.distance + 1}; it.next();) {
+    for(matrix::circle it{$lightmap, at, source.radius}; it.next();) {
       for(int x = it.left; x < it.right; x++) {
         $lightmap[it.y][x] = light_level(source.strength, x, it.y);
         has_light.push_back({(size_t)x, (size_t)it.y});
@@ -25,7 +25,7 @@ namespace lighting {
   }
 
   void LightRender::render_square_light(LightSource source, Point at, PointList &has_light) {
-    for(matrix::in_box it{$lightmap, at.x, at.y, (size_t)source.distance}; it.next();) {
+    for(matrix::in_box it{$lightmap, at.x, at.y, (size_t)floor(source.radius)}; it.next();) {
       if($paths.$paths[it.y][it.x] != WALL_PATH_LIMIT) {
         $lightmap[it.y][it.x] = light_level(source.strength, it.x, it.y);
         has_light.push_back({it.x, it.y});
@@ -38,9 +38,9 @@ namespace lighting {
     clear_light_target(at);
     PointList has_light;
 
-    if(source.distance == 0) {
+    if(source.radius < 1.5f) {
       render_compass_light(source, at, has_light);
-    } else if(source.distance == 1) {
+    } else if(source.radius < 2.0f) {
       render_square_light(source, at, has_light);
     } else {
       render_circle_light(source, at, has_light);

lights.hpp

@@ -10,7 +10,7 @@ namespace lighting {
 
   struct LightSource {
     int strength = 0;  // lower is better
-    int distance = 1;  // higher is farther, in squares
+    float radius = 1.0f;  // higher is farther, in squares
   };
 
   const int MIN = 50;

main.cpp

@@ -33,7 +33,7 @@ void configure_world(DinkyECS::World &world, Map &game_map) {
   world.set<Combat>(player.entity, {100, 10});
   world.set<Tile>(player.entity, {config.PLAYER_TILE});
   world.set<Inventory>(player.entity, {5});
-  world.set<LightSource>(player.entity, {6,1});
+  world.set<LightSource>(player.entity, {6,2.1});
 
   auto enemy = world.entity();
   world.set<Position>(enemy, {game_map.place_entity(1)});
@@ -55,7 +55,7 @@ void configure_world(DinkyECS::World &world, Map &game_map) {
 
   auto wall_torch = world.entity();
   world.set<Position>(wall_torch, {game_map.place_entity(4)});
-  world.set<LightSource>(wall_torch, {3,4});
+  world.set<LightSource>(wall_torch, {3,2.4});
   world.set<Tile>(wall_torch, {"☀"});
 }
 

matrix.cpp

@@ -180,24 +180,24 @@ namespace matrix {
   }
 
 
-  circle::circle(Matrix &mat, Point center, int radius) :
-    center(center), radius(radius)
+  circle::circle(Matrix &mat, Point center, float radius) :
+    center_x(center.x), center_y(center.y), radius(radius)
   {
     width = matrix::width(mat);
     height = matrix::height(mat);
-    top = max(int(center.y - radius), 0);
-    bottom = min(int(center.y + radius), height);
+    top = max(int(floor(center_y - radius)), 0);
+    bottom = min(int(floor(center_y + radius)), height - 1);
 
     y = top;
   }
 
   bool circle::next() {
     y++;
-    if(y < bottom) {
-      dy = y - center.y;
+    if(y <= bottom) {
+      dy = y - center_y;
       dx = floor(sqrt(radius * radius - dy * dy));
-      left = max(0, int(center.x - dx));
-      right = min(width, int(center.x + dx));
+      left = max(0, int(center_x) - dx);
+      right = min(width, int(center_x) + dx + 1);
       return true;
     } else {
       return false;

matrix.hpp

@@ -118,8 +118,9 @@ namespace matrix {
   };
 
   struct circle {
-    Point center;
-    int radius = 0;
+    float center_x;
+    float center_y;
+    float radius = 0.0f;
     int y = 0;
     int dx = 0;
     int dy = 0;
@@ -130,7 +131,7 @@ namespace matrix {
     int width = 0;
     int height = 0;
 
-    circle(Matrix &mat, Point center, int radius);
+    circle(Matrix &mat, Point center, float radius);
     void update();
     bool next();
   };

systems.cpp

@@ -144,7 +144,7 @@ void System::collision(DinkyECS::World &world, Player &player) {
         world.send<Events::GUI>(Events::GUI::LOOT, entity, loot);
         inventory.gold += loot.amount;
         light.strength = 4;
-        light.distance = 2;
+        light.radius = 2.3;
         collider.remove(loot_pos.location);
       } else {
         println("UNKNOWN COLLISION TYPE {}", entity);

tests/matrix.cpp

@@ -226,7 +226,7 @@ TEST_CASE("prototype line algorithm", "[matrix:line]") {
 }
 
 TEST_CASE("prototype circle algorithm", "[matrix:circle]") {
-  for(int count = 0; count < 2000; count++) {
+  for(int count = 0; count < 2; count++) {
     size_t width = Random::uniform<size_t>(10, 13);
     size_t height = Random::uniform<size_t>(10, 15);
     int pos_mod = Random::uniform<int>(-3,3);
@@ -234,7 +234,7 @@ TEST_CASE("prototype circle algorithm", "[matrix:circle]") {
     // create a target for the paths
     Point start{.x=map.width() / 2 + pos_mod, .y=map.height()/2 + pos_mod};
 
-    for(int radius = 2; radius < 10; radius++) {
+    for(float radius = 1.0f; radius < 4.0f; radius += 0.1f) {
       // use an empty map
       Matrix result = map.walls();
 
@@ -250,7 +250,7 @@ TEST_CASE("prototype circle algorithm", "[matrix:circle]") {
         }
       }
 
-      // matrix::dump("RESULT AFTER CIRCLE", result, start.x, start.y);
+      matrix::dump(format("RESULT AFTER CIRCLE radius {}", radius), result, start.x, start.y);
     }
   }
 }