From 853f9385213300b7d966a90d4da960dae5fb9b10 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miloslav=20=C4=8C=C3=AD=C5=BE?= <tastyfish@seznam.cz>
Date: Wed, 12 Sep 2018 17:37:15 +0200
Subject: [PATCH] Add pixel counter

---
 raycastlib.h |  8 ++++++--
 testSDL.c    | 45 ++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 48 insertions(+), 5 deletions(-)

diff --git a/raycastlib.h b/raycastlib.h
index ffa2dbf..30a2294 100644
--- a/raycastlib.h
+++ b/raycastlib.h
@@ -242,6 +242,8 @@ void castRaysMultiHit(Camera cam, ArrayFunction arrayFunc,
 /**
   Using provided functions, renders a complete complex camera view.
 
+  This function should render each screen pixel exactly once.
+
   @param cam camera whose view to render
   @param floorHeightFunc function that returns floor height (in Units)
   @param ceilingHeightFunc same as floorHeightFunc but for ceiling, can also be
@@ -261,6 +263,8 @@ void render(Camera cam, ArrayFunction floorHeightFunc,
   with simple 1-intersection raycasting. The render(...) function can give more
   accurate results than this function, so it's to be considered even for simple
   scenes.
+
+  This function should render each screen pixel exactly once.
 */
 void renderSimple(Camera cam, ArrayFunction floorHeightFunc,
   ArrayFunction typeFunc, PixelFunction pixelFunc, RayConstraints constraints);
@@ -888,8 +892,8 @@ void _columnFunction(HitResult *hits, uint16_t hitCount, uint16_t x, Ray ray)
         _pixelFunction(&p);  
       }
 
-if (z1ScreenCeil > y2)
-  y2 = z1ScreenCeil;
+      if (z1ScreenCeil > y2)
+        y2 = z1ScreenCeil;
     }
 
     // draw floor wall
diff --git a/testSDL.c b/testSDL.c
index d5509f5..8f1960c 100644
--- a/testSDL.c
+++ b/testSDL.c
@@ -21,8 +21,8 @@
 #define LEVEL_X_RES 29
 #define LEVEL_Y_RES 21
 
-#define SCREEN_WIDTH 640
-#define SCREEN_HEIGHT 480
+#define SCREEN_WIDTH 320
+#define SCREEN_HEIGHT 240
 #define MIDDLE_ROW (SCREEN_HEIGHT / 2)
 
 #define TRANSPARENT_COLOR 0b00000111
@@ -48,6 +48,7 @@ Unit zBuffer[SCREEN_WIDTH]; ///< 1D z-buffer for visibility determination.
 Camera camera;
 
 uint32_t pixels[SCREEN_WIDTH * SCREEN_HEIGHT];
+uint32_t pixelCounter[SCREEN_WIDTH * SCREEN_HEIGHT];
 
 typedef struct
 {
@@ -697,6 +698,28 @@ const unsigned char sprite3[] =
 
 const unsigned char *textures[] = {texture1, texture2, texture3, texture4};
 
+void clearPixelCounter()
+{
+  memset(pixelCounter,0,SCREEN_WIDTH * SCREEN_HEIGHT * sizeof(uint32_t));
+}
+
+void writePixelCounter()
+{
+  printf("\npixel counter:\n");
+
+  for (int y = 0; y < SCREEN_HEIGHT; ++y)
+  {
+    for (int x = 0; x < SCREEN_WIDTH; ++x)
+    {
+      uint32_t count = pixelCounter[y * SCREEN_WIDTH + x];      
+
+      if (count != 1) // each pixel should have been rendered only once
+        printf("error: pixel %d %d rendered %d times!\n",x,y,count);
+    }
+
+  }   
+}
+
 uint8_t rgbToIndex(uint8_t r, uint8_t g, uint8_t b)
 {
   return (r & 0b00000111) | ((g & 0b00000111) << 3) | ((b & 0b00000011) << 6);
@@ -860,7 +883,10 @@ void pixelFunc(PixelInfo *pixel)
   b = b > 0 ? b : 0;
   b = b << 8;
 
-  pixels[pixel->position.y * SCREEN_WIDTH + pixel->position.x] = r | g | b;
+  int32_t index = pixel->position.y * SCREEN_WIDTH + pixel->position.x;
+
+  pixels[index] = r | g | b;
+  pixelCounter[index]++;
 }
 
 void draw()
@@ -945,10 +971,23 @@ int main()
   SDL_Event event;
   int running = 1;
 
+  int counter = 0;
+
   while (running)
   {
+    if (counter <= 0)
+      clearPixelCounter();
+
     draw();
 
+    if (counter <= 0)
+    {
+      writePixelCounter();
+      counter = 256;
+    }
+    else
+      counter--;
+
     SDL_UpdateTexture(texture,NULL,pixels,SCREEN_WIDTH * sizeof(uint32_t));
 
     while (SDL_PollEvent(&event))