unify gamma correction concepts (#848)

* unify gamma correction concepts

* fix "gamma correction level" user messages

* pointer constness fix

* fix config help line

src/i_video.c

@@ -1058,29 +1058,34 @@ static void I_RestoreDiskBackground(void)
   disk_to_draw = 0;
 }
 
-static const float gammalevels[18] =
+static const float gammalevels[9] =
 {
     // Darker
     0.50f, 0.55f, 0.60f, 0.65f, 0.70f, 0.75f, 0.80f, 0.85f, 0.90f,
-
-    // No gamma correction
-    1.0f,
-
-    // Lighter
-    1.125f, 1.25f, 1.375f, 1.5f, 1.625f, 1.75f, 1.875f, 2.0f,
 };
 
 static byte gamma2table[18][256];
 
 static void I_InitGamma2Table(void)
 {
-  int i, j;
+  int i, j, k;
 
-  for (i = 0; i < 18; ++i)
+  for (i = 0; i < 9; ++i)
     for (j = 0; j < 256; ++j)
     {
       gamma2table[i][j] = (byte)(pow(j / 255.0, 1.0 / gammalevels[i]) * 255.0 + 0.5);
     }
+
+  // [crispy] 5 original gamma levels
+  for (i = 9, k = 0; i < 18 && k < 5; i += 2, k++)
+    memcpy(gamma2table[i], gammatable[k], 256);
+
+  // [crispy] 4 intermediate gamma levels
+  for (i = 10, k = 0; i < 18 && k < 4; i += 2, k++)
+    for (j = 0; j < 256; ++j)
+    {
+      gamma2table[i][j] = (gammatable[k][j] + gammatable[k + 1][j]) / 2;
+    }
 }
 
 int gamma2;
@@ -1089,21 +1094,12 @@ void I_SetPalette(byte *palette)
 {
    // haleyjd
    int i;
-   byte *gamma;
+   byte *const gamma = gamma2table[gamma2];
    SDL_Color colors[256];
    
    if (!in_graphics_mode)             // killough 8/11/98
       return;
 
-   if (gamma2 != 9) // 1.0f
-   {
-      gamma = gamma2table[gamma2];
-   }
-   else
-   {
-      gamma = gammatable[usegamma];
-   }
-
    for(i = 0; i < 256; ++i)
    {
       colors[i].r = gamma[*palette++];

src/m_menu.c

@@ -3888,19 +3888,18 @@ void static M_SmoothLight(void)
 
 static const char *gamma_strings[] = {
   // Darker
-  "0.50", "0.55", "0.60", "0.65", "0.70", "0.75", "0.80", "0.85", "0.90",
+  "-4", "-3.6", "-3.2", "-2.8", "-2.4", "-2.0", "-1.6", "-1.2", "-0.8",
 
   // No gamma correction
-  "1.0",
+  "0",
 
   // Lighter
-  "1.125", "1.25", "1.375", "1.5", "1.625", "1.75", "1.875", "2.0",
+  "0.5", "1", "1.5", "2", "2.5", "3", "3.5", "4",
   NULL
 };
 
 static void M_ResetGamma(void)
 {
-  usegamma = 0;
   I_SetPalette(W_CacheLumpName("PLAYPAL",PU_CACHE));
 }
 
@@ -5518,17 +5517,11 @@ boolean M_Responder (event_t* ev)
     
       if (M_InputActivated(input_gamma))       // gamma toggle
 	{
-	  usegamma++;
-	  if (usegamma > 4)
-	    usegamma = 0;
-	  players[consoleplayer].message =
-	    usegamma == 0 ? s_GAMMALVL0 :
-	    usegamma == 1 ? s_GAMMALVL1 :
-	    usegamma == 2 ? s_GAMMALVL2 :
-	    usegamma == 3 ? s_GAMMALVL3 :
-	    s_GAMMALVL4;
-	  gamma2 = 9; // 1.0f
-	  I_SetPalette (W_CacheLumpName ("PLAYPAL",PU_CACHE));
+	  gamma2++;
+	  if (gamma2 > 17)
+	    gamma2 = 0;
+	  doomprintf("Gamma correction level %s", gamma_strings[gamma2]);
+	  M_ResetGamma();
 	  return true;                      
 	}
 

src/m_misc.c

@@ -276,7 +276,7 @@ default_t defaults[] = {
     "gamma2",
     (config_t *) &gamma2, NULL,
     {9}, {0,17}, number, ss_gen, wad_no,
-    "custom gamma level (0 = 0.5, 9 = 1.0, 17 = 2.0)"
+    "custom gamma level (0 = -4, 9 = 0, 17 = 4)"
   },
 
   {
@@ -609,13 +609,6 @@ default_t defaults[] = {
     "initial play screen size"
   },
 
-  { //jff 3/6/98 fix erroneous upper limit in range
-    "usegamma",
-    (config_t *) &usegamma, NULL,
-    {0}, {0,4}, number, ss_none, wad_no,
-    "screen brightness (gamma correction)"
-  },
-
   // killough 10/98: compatibility vector:
 
   {

src/v_video.c

@@ -150,8 +150,6 @@ byte gammatable[5][256] =
    251,252,252,253,254,254,255,255}
 };
 
-int usegamma;
-
 //
 // V_InitColorTranslation
 //

src/v_video.h

@@ -97,7 +97,6 @@ typedef enum
 extern byte *screens[5];
 extern int  dirtybox[4];
 extern byte gammatable[5][256];
-extern int  usegamma;        // killough 11/98
 
 //jff 4/24/98 loads color translation lumps
 void V_InitColorTranslation(void);