ref: 14cf34bc65d7584984d26eea4154d58770125e60
parent: beaff1d633f780d2352cb68b880b96df81a1f673
author: Simon Howard <fraggle@gmail.com>
date: Sat Aug 21 21:21:27 EDT 2010
Change span drawing functions to work the same as Vanilla, so that in screenshots, floors and ceilings are pixel-perfect identical to Vanilla Doom (thanks Porsche Monty). Subversion-branch: /trunk/chocolate-doom Subversion-revision: 1963
--- a/src/r_draw.c
+++ b/src/r_draw.c
@@ -594,51 +594,57 @@
// Draws the actual span.
void R_DrawSpan (void)
{ - fixed_t xfrac;
- fixed_t yfrac;
- byte* dest;
- int count;
- int spot;
-
-#ifdef RANGECHECK
+ unsigned int position, step;
+ byte *dest;
+ int count;
+ int spot;
+ unsigned int xtemp, ytemp;
+
+#ifdef RANGECHECK
if (ds_x2 < ds_x1
|| ds_x1<0
- || ds_x2>=SCREENWIDTH
+ || ds_x2>=SCREENWIDTH
|| (unsigned)ds_y>SCREENHEIGHT)
{I_Error( "R_DrawSpan: %i to %i at %i",
ds_x1,ds_x2,ds_y);
}
-// dscount++;
-#endif
+// dscount++;
+#endif
-
- xfrac = ds_xfrac;
- yfrac = ds_yfrac;
-
+ // Pack position and step variables into a single 32-bit integer,
+ // with x in the top 16 bits and y in the bottom 16 bits. For
+ // each 16-bit part, the top 6 bits are the integer part and the
+ // bottom 10 bits are the fractional part of the pixel position.
+
+ position = ((ds_xfrac << 10) & 0xffff0000)
+ | ((ds_yfrac >> 6) & 0x0000ffff);
+ step = ((ds_xstep << 10) & 0xffff0000)
+ | ((ds_ystep >> 6) & 0x0000ffff);
+
dest = ylookup[ds_y] + columnofs[ds_x1];
// We do not check for zero spans here?
- count = ds_x2 - ds_x1;
+ count = ds_x2 - ds_x1;
- do
+ do
{- // Current texture index in u,v.
- spot = ((yfrac>>(16-6))&(63*64)) + ((xfrac>>16)&63);
+ // Calculate current texture index in u,v.
+ ytemp = (position >> 4) & 0x0fc0;
+ xtemp = (position >> 26);
+ spot = xtemp | ytemp;
// Lookup pixel from flat texture tile,
// re-index using light/colormap.
*dest++ = ds_colormap[ds_source[spot]];
- // Next step in u,v.
- xfrac += ds_xstep;
- yfrac += ds_ystep;
-
- } while (count--);
-}
+ position += step;
+ } while (count--);
+}
+
// UNUSED.
// Loop unrolled by 4.
#if 0
@@ -715,18 +721,18 @@
//
// Again..
//
-void R_DrawSpanLow (void)
-{ - fixed_t xfrac;
- fixed_t yfrac;
- byte* dest;
- int count;
- int spot;
-
-#ifdef RANGECHECK
+void R_DrawSpanLow (void)
+{+ unsigned int position, step;
+ unsigned int xtemp, ytemp;
+ byte *dest;
+ int count;
+ int spot;
+
+#ifdef RANGECHECK
if (ds_x2 < ds_x1
|| ds_x1<0
- || ds_x2>=SCREENWIDTH
+ || ds_x2>=SCREENWIDTH
|| (unsigned)ds_y>SCREENHEIGHT)
{I_Error( "R_DrawSpan: %i to %i at %i",
@@ -733,31 +739,36 @@
ds_x1,ds_x2,ds_y);
}
// dscount++;
-#endif
-
- xfrac = ds_xfrac;
- yfrac = ds_yfrac;
-
- count = (ds_x2 - ds_x1);
+#endif
+ position = ((ds_xfrac << 10) & 0xffff0000)
+ | ((ds_yfrac >> 6) & 0x0000ffff);
+ step = ((ds_xstep << 10) & 0xffff0000)
+ | ((ds_ystep >> 6) & 0x0000ffff);
+
+ count = (ds_x2 - ds_x1);
+
// Blocky mode, need to multiply by 2.
ds_x1 <<= 1;
ds_x2 <<= 1;
-
+
dest = ylookup[ds_y] + columnofs[ds_x1];
-
- do
- { - spot = ((yfrac>>(16-6))&(63*64)) + ((xfrac>>16)&63);
+
+ do
+ {+ // Calculate current texture index in u,v.
+ ytemp = (position >> 4) & 0x0fc0;
+ xtemp = (position >> 26);
+ spot = xtemp | ytemp;
+
// Lowres/blocky mode does it twice,
// while scale is adjusted appropriately.
- *dest++ = ds_colormap[ds_source[spot]];
*dest++ = ds_colormap[ds_source[spot]];
-
- xfrac += ds_xstep;
- yfrac += ds_ystep;
+ *dest++ = ds_colormap[ds_source[spot]];
- } while (count--);
+ position += step;
+
+ } while (count--);
}
//