From 6533f950d2df07f166e0fcc973a88e2de731c100 Mon Sep 17 00:00:00 2001
From: "Zed A. Shaw" <zed.shaw@gmail.com>
Date: Tue, 14 Jan 2025 20:07:37 -0500
Subject: [PATCH] Quick and dirty idea for a poor-man's lighting effect.

---
 sfmlcaster.cpp | 42 ++++++++++++++++++++++++++++++------------
 1 file changed, 30 insertions(+), 12 deletions(-)

diff --git a/sfmlcaster.cpp b/sfmlcaster.cpp
index 2ef0321..65331f5 100644
--- a/sfmlcaster.cpp
+++ b/sfmlcaster.cpp
@@ -85,8 +85,25 @@ double spriteDistance[numSprites];
 
 std::vector<uint32_t> texture[numTextures];
 
+union RGBA {
+  struct {
+    uint8_t r;
+    uint8_t g;
+    uint8_t b;
+    uint8_t a;
+  } color;
+
+  uint32_t out;
+};
+
+inline void RGBA_brightness(RGBA& pixel, double distance) {
+  pixel.color.r /= distance;
+  pixel.color.g /= distance;
+  pixel.color.b /= distance;
+}
+
 #define pixcoord(X, Y) ((Y) * RAY_VIEW_WIDTH) + (X)
-uint32_t pixels[RAY_VIEW_WIDTH * RAY_VIEW_HEIGHT] = {0};
+RGBA pixels[RAY_VIEW_WIDTH * RAY_VIEW_HEIGHT] = {{.out=0}};
 
 sf::Texture view_texture;
 sf::Sprite view_sprite;
@@ -166,18 +183,19 @@ void draw_line(sf::RenderWindow &window, Point start, Point end, uint32_t color)
       y = y + sy;
     }
 
-    pixels[pixcoord(x,y)] = color;
+    pixels[pixcoord(x,y)].out = color;
   }
 }
 
 void clear(sf::RenderWindow &window) {
-  std::fill_n(pixels, RAY_VIEW_WIDTH * RAY_VIEW_HEIGHT, 0);
-  window.clear();
+//   std::fill_n((uint32_t *)pixels, RAY_VIEW_WIDTH * RAY_VIEW_HEIGHT, 0);
+//   window.clear();
 }
 
 void ray_casting(sf::RenderWindow &window, Matrix& map) {
   int w = RAY_VIEW_WIDTH;
   int h = RAY_VIEW_HEIGHT;
+  double perpWallDist;
 
   // WALL CASTING
   for(int x = 0; x < w; x++) {
@@ -197,7 +215,6 @@ void ray_casting(sf::RenderWindow &window, Matrix& map) {
     // length of ray from one x or y-side to next x or y-side
     double deltaDistX = std::abs(1.0 / rayDirX);
     double deltaDistY = std::abs(1.0 / rayDirY);
-    double perpWallDist;
 
     int stepX = 0;
     int stepY = 0;
@@ -276,14 +293,13 @@ void ray_casting(sf::RenderWindow &window, Matrix& map) {
     for(int y = drawStart; y < drawEnd; y++) {
       int texY = (int)texPos & (texHeight - 1);
       texPos += step;
-      uint32_t color = texture[texNum][texHeight * texY + texX];
-
-      pixels[pixcoord(x, y)] = color;
+      RGBA pixel{.out=texture[texNum][texHeight * texY + texX]};
+      RGBA_brightness(pixel, perpWallDist);
+      pixels[pixcoord(x, y)] = pixel;
     }
 
     // SET THE ZBUFFER FOR THE SPRITE CASTING
     ZBuffer[x] = perpWallDist;
-
   }
 
   // SPRITE CASTING
@@ -357,7 +373,9 @@ void ray_casting(sf::RenderWindow &window, Matrix& map) {
           uint32_t color = sprite_texture[texWidth * texY + texX];
           // poor person's transparency, get current color from the texture
           if((color & 0x00FFFFFF) != 0) {
-            pixels[pixcoord(stripe, y)] = color;
+            RGBA pixel{.out=color};
+            RGBA_brightness(pixel, perpWallDist);
+            pixels[pixcoord(stripe, y)] = pixel;
           }
         }
       }
@@ -421,11 +439,11 @@ void draw_ceiling_floor(sf::RenderWindow &window) {
 
       // FLOOR
       color = texture[floorTexture][texWidth * ty + tx];
-      pixels[pixcoord(x, y)] = color;
+      pixels[pixcoord(x, y)].out = color;
 
       // CEILING
       color = texture[ceilingTexture][texWidth * ty + tx];
-      pixels[pixcoord(x, screenHeight - y - 1)] = color;
+      pixels[pixcoord(x, screenHeight - y - 1)].out = color;
     }
   }
 }