Brought in Amit's latest and tweaked a few more build options for enabling some safety checks in GCC.

amt/main.cpp

@@ -57,6 +57,9 @@ int main() {
 
   Stats stats;
 
+  // NOTE: Enable this to lock frames at 60
+  window.setFramerateLimit(60);
+
   while(window.isOpen()) {
     auto start = std::chrono::high_resolution_clock::now();
     rayview.render();

amt/raycaster.cpp

@@ -2,6 +2,7 @@
 #include "amt/texture.hpp"
 #include "amt/pixel.hpp"
 #include "constants.hpp"
+#include "thread.hpp"
 
 #define AMT_LIGHT
 
@@ -11,14 +12,14 @@ using namespace fmt;
 #ifdef AMT_LIGHT
 static constexpr auto room_brightness = 0.3f; // increse this to increase the room brightness. Higher value means brighter room.
 
-inline static constexpr amt::RGBA dumb_lighting(amt::RGBA pixel, double distance, double distance_from_center) {
+inline static constexpr amt::RGBA dumb_lighting(amt::RGBA pixel, float distance, float distance_from_center) {
   auto const dim_pixel = pixel * room_brightness;
   if (distance_from_center >= 0) {
-    auto const min_brightness = 1. / std::max(distance_from_center, 0.5); // farther away from the center darker it gets
+    auto const min_brightness = 1.f / std::max(distance_from_center, 0.5f); // farther away from the center darker it gets
-    auto const max_brightness = 1.; // brighness should not exceed 1
+    auto const max_brightness = 1.f; // brighness should not exceed 1
     auto const pixel_brightness = std::max(min_brightness, std::min(max_brightness, distance));
-    auto const yellow_brightness = float(distance_from_center * 60);
 
+    auto const yellow_brightness = float(distance_from_center * 60);
     amt::RGBA const yellow = amt::HSLA(40, 20, yellow_brightness);
 
     auto temp = (pixel / pixel_brightness).blend<amt::BlendMode::softLight>(yellow);
@@ -29,6 +30,7 @@ inline static constexpr amt::RGBA dumb_lighting(amt::RGBA pixel, double distance
 }
 #else
 inline static constexpr amt::RGBA dumb_lighting(amt::RGBA pixel, double distance, double distance_from_center) {
+  (void)distance_from_center;
   if(distance < 0.9) return pixel;
   return pixel / distance;
 }
@@ -45,7 +47,9 @@ Raycaster::Raycaster(sf::RenderWindow& window, Matrix &map, unsigned width, unsi
   $map(map),
   spriteOrder(textures.NUM_SPRITES),
   spriteDistance(textures.NUM_SPRITES),
-  ZBuffer(width)
+  ZBuffer(width),
+  $radius(std::min($height, $width) / 2),
+  $r_sq($radius * $radius)
 {
   $window.setVerticalSyncEnabled(VSYNC);
   view_sprite.setPosition({0, 0});
@@ -74,9 +78,6 @@ void Raycaster::clear() {
 }
 
 void Raycaster::sprite_casting() {
-  const int textureWidth = textures.TEXTURE_WIDTH;
-  const int textureHeight = textures.TEXTURE_HEIGHT;
-
   // sort sprites from far to close
   for(int i = 0; i < textures.NUM_SPRITES; i++) {
     auto& sprite = textures.get_sprite(i);
@@ -90,8 +91,10 @@ void Raycaster::sprite_casting() {
 
   sort_sprites(spriteOrder, spriteDistance, textures.NUM_SPRITES);
 
+  /*for(int i = 0; i < textures.NUM_SPRITES; i++) {*/
   // after sorting the sprites, do the projection
-  for(int i = 0; i < textures.NUM_SPRITES; i++) {
+  // Be careful about capturing stack variables.
+  amt::parallel_for<1>(pool, 0, textures.NUM_SPRITES, [this, textureWidth = textures.TEXTURE_WIDTH, textureHeight = textures.TEXTURE_HEIGHT](size_t i){
     int sprite_index = spriteOrder[i];
     Sprite& sprite_rec = textures.get_sprite(sprite_index);
     auto& sprite_texture = textures.get_texture(sprite_rec.texture);
@@ -139,33 +142,39 @@ void Raycaster::sprite_casting() {
       // the conditions in the if are:
       // 1) it's in front of the camera plane so you don't see things behind you
       // 2) ZBuffer, with perpendicular distance
+      if (texX < 0) continue;
       if(transformY > 0 && transformY < ZBuffer[stripe]) {
         for(int y = drawStartY; y < drawEndY; y++) {
           //256 and 128 factors to avoid floats
           int d = (y - vMoveScreen) * 256 - $height * 128 + spriteHeight * 128;
           int texY = ((d * textureHeight) / spriteHeight) / 256;
+          if ((size_t)texY >= sprite_texture.rows()) continue;
           //get current color from the texture
-          // BUG: this crashes sometimes when the math goes out of bounds
-          if(texY < 0 || texY >= (int)sprite_texture.rows()) continue;
           auto color = sprite_texture[texY][texX];
           // poor person's transparency, get current color from the texture
-          pixels[y][stripe] = (color.to_hex() & 0xffffff00) ? color: pixels[y][stripe];
+          if (!(color.to_hex() & 0xffffff00)) continue;
+          auto dist = get_distance_from_center(stripe, y);
+          pixels[y][stripe] = dumb_lighting(color, d, dist);
         }
       }
     }
-   }
+   });
+}
+
+float Raycaster::get_distance_from_center(int x, int y) const noexcept {
+  float cx = $width / 2;
+  float cy = $height / 2;
+  auto dx = cx - x;
+  auto dy = cy - y;
+  return ($r_sq - dx * dx - dy * dy) / $r_sq;
 }
 
 void Raycaster::cast_rays() {
-  double perpWallDist = 0;
-
-  auto const cx = $width / 2;
-  auto const cy = $height / 2;
-  double const radius = std::min($height, $width) / 2;
-  double const r_sq = radius * radius;
 
   // WALL CASTING
-  for(int x = 0; x < $width; x++) {
+  /*for(int x = 0; x < $width; x++) {*/
+  amt::parallel_for<32>(pool, 0, static_cast<std::size_t>($width), [this](size_t x){
+    double perpWallDist = 0;
     // calculate ray position and direction
     double cameraX = 2 * x / double($width) - 1; // x-coord in camera space
     double rayDirX = dirX + planeX * cameraX;
@@ -260,23 +269,24 @@ void Raycaster::cast_rays() {
     for(int y = drawStart; y < drawEnd; y++) {
       int texY = (int)texPos & (textures.TEXTURE_HEIGHT - 1);
       texPos += step;
-      auto const dx = cx - x;
+      auto dist = get_distance_from_center(x, y);
-      auto const dy = cy - y;
+      auto color = dumb_lighting(texture[texY][texX], perpWallDist, dist);
-      double const dist = dx * dx + dy * dy;
-      auto color = dumb_lighting(texture[texY][texX], perpWallDist, (r_sq - dist) / r_sq);
       pixels[y][x] = color;
     }
 
     // SET THE ZBUFFER FOR THE SPRITE CASTING
     ZBuffer[x] = perpWallDist;
-  }
+  });
 }
 
 void Raycaster::draw_ceiling_floor() {
-  const size_t textureWidth = textures.TEXTURE_WIDTH;
-  const size_t textureHeight = textures.TEXTURE_HEIGHT;
 
-  for(int y = $height / 2 + 1; y < $height; ++y) {
+  /*for(int y = $height / 2 + 1; y < $height; ++y) {*/
+
+  auto const h = static_cast<size_t>($height);
+  amt::parallel_for<32>(pool, h / 2, h, [this, $height=h](size_t y){
+    const size_t textureWidth = textures.TEXTURE_WIDTH;
+    const size_t textureHeight = textures.TEXTURE_HEIGHT;
     // rayDir for leftmost ray (x=0) and rightmost (x = w)
     float rayDirX0 = dirX - planeX;
     float rayDirY0 = dirY - planeY;
@@ -327,10 +337,12 @@ void Raycaster::draw_ceiling_floor() {
 
       #ifdef AMT_LIGHT
       // FLOOR
-      pixels[y][x] = textures.floor[ty][tx] * room_brightness;
+      auto dist_floor = get_distance_from_center(x, y);
+      pixels[y][x] = dumb_lighting(textures.floor[ty][tx], p, dist_floor);
 
       // CEILING
-      pixels[$height - y - 1][x] = textures.ceiling[ty][tx] * room_brightness;
+      auto dist_ceiling = get_distance_from_center(x, $height - y - 1);
+      pixels[$height - y - 1][x] = dumb_lighting(textures.ceiling[ty][tx], p, dist_ceiling);
       #else
       // FLOOR
       pixels[y][x] = textures.floor[ty][tx];
@@ -340,14 +352,18 @@ void Raycaster::draw_ceiling_floor() {
       #endif
 
     }
-  }
+  });
 
 }
 
 void Raycaster::render() {
   draw_ceiling_floor();
+  // This wait to prevent data-race
+  pool.wait(); // Try to remove this to see unbelievable performance
   cast_rays();
+  pool.wait(); // Try to remove this too
   sprite_casting();
+  pool.wait();
   draw_pixel_buffer();
 }
 

amt/raycaster.hpp

@@ -13,6 +13,7 @@
 #include "amt/pixel.hpp"
 #include "amt/texture.hpp"
 #include <memory>
+#include "thread.hpp"
 
 using Matrix = amt::Matrix<int>;
 
@@ -43,6 +44,9 @@ struct Raycaster {
   std::vector<int> spriteOrder;
   std::vector<double> spriteDistance;
   std::vector<double> ZBuffer; // width
+  float $radius; // std::min($height, $width) / 2;
+  float $r_sq; // = radius * radius;
+  amt::thread_pool_t pool;
 
   Raycaster(sf::RenderWindow& window, Matrix &map, unsigned width, unsigned height);
 
@@ -59,10 +63,11 @@ struct Raycaster {
   void run(double speed, int dir);
   void rotate(double speed, int dir);
   void position_camera(float player_x, float player_y);
+  float get_distance_from_center(int x, int y) const noexcept;
 
   void set_position(int x, int y);
   inline size_t pixcoord(int x, int y) {
     return ((y) * $width) + (x);
   }
 
-};
+};

constants.hpp

@@ -7,6 +7,7 @@ constexpr const int RAY_VIEW_Y=0;
 constexpr const int SCREEN_HEIGHT=720;
 constexpr const int SCREEN_WIDTH=1280;
 constexpr const bool VSYNC=false;
+constexpr const int FRAME_LIMIT=30;
 #ifdef NDEBUG
 constexpr const bool DEBUG_BUILD=false;
 #else

main.cpp

@@ -57,6 +57,8 @@ int main() {
 
   Stats stats;
 
+  window.setFramerateLimit(FRAME_LIMIT);
+
   while(window.isOpen()) {
     auto start = std::chrono::high_resolution_clock::now();
     rayview.render();

meson.build

@@ -63,5 +63,7 @@ executable('amtcaster', [
   'amt/texture.cpp',
   'amt/raycaster.cpp',
   'amt/main.cpp'
-  ], override_options: exe_defaults,
+  ],
+  cpp_args: ['-std=c++23'],
+  override_options: exe_defaults,
   dependencies: dependencies)