- Rewrote wide sky texture scaling again. This time, it should work for any

size textures at any scale. I also tried doing sky scrolling on the sky
  cylinder, but that didn't look so good, so I left it in screen space.


SVN r1932 (trunk)

docs/rh-log.txt

@@ -1,3 +1,8 @@
+October 24, 2009
+- Rewrote wide sky texture scaling again. This time, it should work for any
+  size textures at any scale. I also tried doing sky scrolling on the sky
+  cylinder, but that didn't look so good, so I left it in screen space.
+
 October 23, 2009
 - Fixed: When giving completely new ammo, the backpack did not clamp the
   amount given to the ammo's max amount.

src/r_anim.cpp

@@ -834,6 +834,6 @@ void R_UpdateAnimations (DWORD mstime)
 
 	// Scroll the sky
 	double ms = (double)mstime * FRACUNIT;
-	sky1pos = fixed_t(fmod (ms * level.skyspeed1, double(TexMan[sky1texture]->GetScaledWidth() << FRACBITS)));
-	sky2pos = fixed_t(fmod (ms * level.skyspeed2, double(TexMan[sky2texture]->GetScaledWidth() << FRACBITS)));
+	sky1pos = ms * level.skyspeed1;
+	sky2pos = ms * level.skyspeed2;
 }

src/r_plane.cpp

@@ -745,8 +745,8 @@ inline void R_MakeSpans (int x, int t1, int b1, int t2, int b2, void (*mapfunc)(
 static FTexture *frontskytex, *backskytex;
 static angle_t skyflip;
 static int frontpos, backpos;
-static fixed_t frontxScale, backxScale;
 static fixed_t frontyScale;
+static fixed_t frontcyl, backcyl;
 int frontiScale;
 
 extern fixed_t swall[MAXWIDTH];
@@ -765,15 +765,15 @@ static int skycolplace;
 static const BYTE *R_GetOneSkyColumn (FTexture *fronttex, int x)
 {
 	angle_t column = (viewangle + xtoviewangle[x]) ^ skyflip;
-	return fronttex->GetColumn (MulScale32((column >> sky1shift) + frontpos, frontxScale), NULL);
+	return fronttex->GetColumn((MulScale16(column, frontcyl) + frontpos) >> FRACBITS, NULL);
 }
 
 // Get a column of sky when there are two overlapping sky textures
 static const BYTE *R_GetTwoSkyColumns (FTexture *fronttex, int x)
 {
 	DWORD ang = (viewangle + xtoviewangle[x]) ^ skyflip;
-	DWORD angle1 = (DWORD)MulScale32((ang >> sky1shift) + frontpos, frontxScale);
-	DWORD angle2 = (DWORD)MulScale32((ang >> sky2shift) + backpos, backxScale);
+	DWORD angle1 = (DWORD)((MulScale16(ang, frontcyl) + frontpos) >> FRACBITS);
+	DWORD angle2 = (DWORD)((MulScale16(ang, backcyl) + backpos) >> FRACBITS);
 
 	// Check if this column has already been built. If so, there's
 	// no reason to waste time building it again.
@@ -848,12 +848,6 @@ static void R_DrawSky (visplane_t *pl)
 	rw_pic = frontskytex;
 	rw_offset = 0;
 
-	frontxScale = rw_pic->xScale;
-	if (backskytex != NULL)
-	{
-		backxScale = backskytex->xScale;
-	}
-
 	frontyScale = rw_pic->yScale;
 	dc_texturemid = MulScale16 (skytexturemid/*-viewz*/, frontyScale);
 
@@ -1250,6 +1244,7 @@ ADD_STAT(skyboxes)
 void R_DrawSkyPlane (visplane_t *pl)
 {
 	FTextureID sky1tex, sky2tex;
+	double frontdpos, backdpos;
 
 	if ((level.flags & LEVEL_SWAPSKIES) && !(level.flags & LEVEL_DOUBLESKY))
 	{
@@ -1272,15 +1267,18 @@ void R_DrawSkyPlane (visplane_t *pl)
 			else
 				backskytex = NULL;
 			skyflip = 0;
-			frontpos = sky1pos;
-			backpos = sky2pos;
+			frontdpos = sky1pos;
+			backdpos = sky2pos;
+			frontcyl = sky1cyl;
+			backcyl = sky2cyl;
 		}
 		else if (pl->sky == PL_SKYFLAT)
 		{	// use sky2
 			frontskytex = TexMan(sky2tex);
 			backskytex = NULL;
+			frontcyl = sky2cyl;
 			skyflip = 0;
-			frontpos = sky2pos;
+			frontdpos = sky2pos;
 		}
 		else
 		{	// MBF's linedef-controlled skies
@@ -1313,7 +1311,7 @@ void R_DrawSkyPlane (visplane_t *pl)
 			// to allow sky rotation as well as careful positioning.
 			// However, the offset is scaled very small, so that it
 			// allows a long-period of sky rotation.
-			frontpos = (-s->GetTextureXOffset(pos)) >> 6;
+			frontdpos = (-s->GetTextureXOffset(pos)) >> 6;
 
 			// Vertical offset allows careful sky positioning.
 			dc_texturemid = s->GetTextureYOffset(pos) - 28*FRACUNIT;
@@ -1324,12 +1322,18 @@ void R_DrawSkyPlane (visplane_t *pl)
 			// to make it easier to use the new feature, while to still
 			// allow old sky textures to be used.
 			skyflip = l->args[2] ? 0u : ~0u;
+
+			frontcyl = MAX(frontskytex->GetWidth(), frontskytex->xScale >> (16 - 10));
+			if (skystretch && frontskytex->GetScaledWidth() < 512)
+			{
+				frontcyl >>= 1;
 			}
 		}
-//	frontpos = FixedMul(frontpos, frontskytex->xScale/2);
+	}
+	frontpos = int(fmod(frontdpos, double(sky1cyl * 65536.0)));
 	if (backskytex != NULL)
 	{
-		backpos = FixedMul(backpos, backskytex->xScale);
+		backpos = int(fmod(backdpos, double(sky2cyl * 65536.0)));
 	}
 
 	bool fakefixed = false;

src/r_sky.cpp

@@ -47,9 +47,8 @@ int			skystretch;
 fixed_t		skyheight;					
 fixed_t		skyiscale;
 
-int			sky1shift,		sky2shift;
-fixed_t		sky1pos=0,		sky1speed=0;
-fixed_t		sky2pos=0,		sky2speed=0;
+fixed_t		sky1cyl,		sky2cyl;
+double		sky1pos,		sky2pos;
 
 // [RH] Stretch sky texture if not taller than 128 pixels?
 CUSTOM_CVAR (Bool, r_stretchsky, true, CVAR_ARCHIVE)
@@ -114,10 +113,26 @@ void R_InitSkyMap ()
 		skyscale = Scale (skyscale, 2048, FieldOfView);
 	}
 
-	// The (standard Doom) sky map is 256*128*4 maps.
-	int swidth = skytex1->GetScaledWidth();
-	sky1shift = 22 - 16 + (skystretch && swidth < 512) - (swidth >= 1024 && skytex1->xScale >= 4*FRACUNIT);
-	swidth = skytex2->GetScaledWidth();
-	sky2shift = 22 - 16 + (skystretch && swidth < 512) - (swidth >= 1024 && skytex2->xScale >= 4*FRACUNIT);
+	// The standard Doom sky texture is 256 pixels wide, repeated 4 times over 360 degrees,
+	// giving a total sky width of 1024 pixels. So if the sky texture is no wider than 1024,
+	// we map it to a cylinder with circumfrence 1024. For larger ones, we use the width of
+	// the texture as the cylinder's circumfrence.
+	sky1cyl = MAX(skytex1->GetWidth(), skytex1->xScale >> (16 - 10));
+	sky2cyl = MAX(skytex2->GetWidth(), skytex2->xScale >> (16 - 10));
+
+	// If we are stretching short skies, we also stretch them horizontally by halving the
+	// circumfrence of the sky cylinder, unless the texture is 512 or more pixels wide,
+	// in which case we only stretch it vertically.
+	if (skystretch)
+	{
+		if (skytex1->GetScaledWidth() < 512)
+		{
+			sky1cyl >>= 1;
+		}
+		if (skytex2->GetScaledWidth() < 512)
+		{
+			sky2cyl >>= 1;
+		}
+	}
 }
 

src/r_sky.h

@@ -24,11 +24,11 @@
 
 #include "textures/textures.h"
 
-extern int		sky1shift,		sky2shift;
 
 extern FTextureID	skyflatnum;
+extern fixed_t		sky1cyl,		sky2cyl;
 extern FTextureID	sky1texture,	sky2texture;
-extern fixed_t	sky1pos,		sky2pos;
+extern double		sky1pos,		sky2pos;
 extern fixed_t	skytexturemid;
 extern int		skystretch;
 extern fixed_t	skyiscale;