ref: 9d7126c11b5f1577b00987b8d5f0f7f761b012d7
dir: /src/i_scale.c/
// Emacs style mode select -*- C++ -*-
//-----------------------------------------------------------------------------
//
// Copyright(C) 1993-1996 Id Software, Inc.
// Copyright(C) 2005,2006 Simon Howard
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
// 02111-1307, USA.
//
// DESCRIPTION:
// Screen scale-up code:
// 1x,2x,3x,4x pixel doubling
// Aspect ratio-correcting stretch functions
//
//-----------------------------------------------------------------------------
#include "doomdef.h"
#include "doomtype.h"
#include "z_zone.h"
// Should be screens[0]
static byte *src_buffer;
// Destination buffer, ie. screen->pixels.
static byte *dest_buffer;
// Pitch of destination buffer, ie. screen->pitch.
static int dest_pitch;
// Lookup tables used for aspect ratio correction stretching code.
// stretch_tables[0] : 20% / 80%
// stretch_tables[1] : 40% / 60%
// All other combinations can be reached from these two tables.
static byte *stretch_tables[2];
// Called to set the source and destination buffers before doing the
// scale.
void I_InitScale(byte *_src_buffer, byte *_dest_buffer, int _dest_pitch)
{
src_buffer = _src_buffer;
dest_buffer = _dest_buffer;
dest_pitch = _dest_pitch;
}
//
// Pixel doubling scale-up functions.
//
// 1x scale doesn't really do any scaling: it just copies the buffer
// a line at a time for when pitch != SCREENWIDTH (!native_surface)
void I_Scale1x(int x1, int y1, int x2, int y2)
{
byte *bufp, *screenp;
int y;
int w = x2 - x1;
// Need to byte-copy from buffer into the screen buffer
bufp = src_buffer + y1 * SCREENWIDTH + x1;
screenp = (byte *) dest_buffer + y1 * dest_pitch + x1;
for (y=y1; y<y2; ++y)
{
memcpy(screenp, bufp, w);
screenp += dest_pitch;
bufp += SCREENWIDTH;
}
}
void I_Scale2x(int x1, int y1, int x2, int y2)
{
byte *bufp, *screenp, *screenp2;
int x, y;
int multi_pitch;
multi_pitch = dest_pitch * 2;
bufp = src_buffer + y1 * SCREENWIDTH + x1;
screenp = (byte *) dest_buffer + (y1 * dest_pitch + x1) * 2;
screenp2 = screenp + dest_pitch;
for (y=y1; y<y2; ++y)
{
byte *sp, *sp2, *bp;
sp = screenp;
sp2 = screenp2;
bp = bufp;
for (x=x1; x<x2; ++x)
{
*sp++ = *bp; *sp++ = *bp;
*sp2++ = *bp; *sp2++ = *bp;
++bp;
}
screenp += multi_pitch;
screenp2 += multi_pitch;
bufp += SCREENWIDTH;
}
}
void I_Scale3x(int x1, int y1, int x2, int y2)
{
byte *bufp, *screenp, *screenp2, *screenp3;
int x, y;
int multi_pitch;
multi_pitch = dest_pitch * 3;
bufp = src_buffer + y1 * SCREENWIDTH + x1;
screenp = (byte *) dest_buffer + (y1 * dest_pitch + x1) * 3;
screenp2 = screenp + dest_pitch;
screenp3 = screenp + dest_pitch * 2;
for (y=y1; y<y2; ++y)
{
byte *sp, *sp2, *sp3, *bp;
sp = screenp;
sp2 = screenp2;
sp3 = screenp3;
bp = bufp;
for (x=x1; x<x2; ++x)
{
*sp++ = *bp; *sp++ = *bp; *sp++ = *bp;
*sp2++ = *bp; *sp2++ = *bp; *sp2++ = *bp;
*sp3++ = *bp; *sp3++ = *bp; *sp3++ = *bp;
++bp;
}
screenp += multi_pitch;
screenp2 += multi_pitch;
screenp3 += multi_pitch;
bufp += SCREENWIDTH;
}
}
void I_Scale4x(int x1, int y1, int x2, int y2)
{
byte *bufp, *screenp, *screenp2, *screenp3, *screenp4;
int x, y;
int multi_pitch;
multi_pitch = dest_pitch * 4;
bufp = src_buffer + y1 * SCREENWIDTH + x1;
screenp = (byte *) dest_buffer + (y1 * dest_pitch + x1) * 4;
screenp2 = screenp + dest_pitch;
screenp3 = screenp + dest_pitch * 2;
screenp4 = screenp + dest_pitch * 3;
for (y=y1; y<y2; ++y)
{
byte *sp, *sp2, *sp3, *sp4, *bp;
sp = screenp;
sp2 = screenp2;
sp3 = screenp3;
sp4 = screenp4;
bp = bufp;
for (x=x1; x<x2; ++x)
{
*sp++ = *bp; *sp++ = *bp; *sp++ = *bp; *sp++ = *bp;
*sp2++ = *bp; *sp2++ = *bp; *sp2++ = *bp; *sp2++ = *bp;
*sp3++ = *bp; *sp3++ = *bp; *sp3++ = *bp; *sp3++ = *bp;
*sp4++ = *bp; *sp4++ = *bp; *sp4++ = *bp; *sp4++ = *bp;
++bp;
}
screenp += multi_pitch;
screenp2 += multi_pitch;
screenp3 += multi_pitch;
screenp4 += multi_pitch;
bufp += SCREENWIDTH;
}
}
// Search through the given palette, finding the nearest color that matches
// the given color.
static int FindNearestColor(byte *palette, int r, int g, int b)
{
byte *col;
int best;
int best_diff;
int diff;
int i;
best = 0;
best_diff = INT_MAX;
for (i=0; i<256; ++i)
{
col = palette + i * 3;
diff = (r - col[0]) * (r - col[0])
+ (g - col[1]) * (g - col[1])
+ (b - col[2]) * (b - col[2]);
if (diff == 0)
{
return i;
}
else if (diff < best_diff)
{
best = i;
best_diff = diff;
}
}
return best;
}
// Create a stretch table. This is a lookup table for blending colors.
// pct specifies the bias between the two colors: 0 = all y, 100 = all x.
// NB: This is identical to the lookup tables used in other ports for
// translucency.
static byte *GenerateStretchTable(byte *palette, int pct)
{
byte *result;
int x, y;
int r, g, b;
byte *col1;
byte *col2;
result = Z_Malloc(256 * 256, PU_STATIC, NULL);
for (x=0; x<256; ++x)
{
for (y=0; y<256; ++y)
{
col1 = palette + x * 3;
col2 = palette + y * 3;
r = (((int) col1[0]) * pct + ((int) col2[0]) * (100 - pct)) / 100;
g = (((int) col1[1]) * pct + ((int) col2[1]) * (100 - pct)) / 100;
b = (((int) col1[2]) * pct + ((int) col2[2]) * (100 - pct)) / 100;
result[x * 256 + y] = FindNearestColor(palette, r, g, b);
}
}
return result;
}
// Called at startup to generate the lookup tables for aspect ratio
// correcting scale up.
void I_InitStretchTables(byte *palette)
{
// We only actually need two lookup tables:
//
// mix 0% = just write line 1
// mix 20% = stretch_tables[0]
// mix 40% = stretch_tables[1]
// mix 60% = stretch_tables[1] used backwards
// mix 80% = stretch_tables[0] used backwards
// mix 100% = just write line 2
printf("I_InitStretchTables: Generating lookup tables..");
fflush(stdout);
stretch_tables[0] = GenerateStretchTable(palette, 20);
printf(".."); fflush(stdout);
stretch_tables[1] = GenerateStretchTable(palette, 40);
puts("");
}
//
// Aspect ratio correcting scale up functions.
//
// These double up pixels to stretch the screen when using a 4:3
// screen mode.
//
static void WriteBlendedLine1x(byte *dest, byte *src1, byte *src2,
byte *stretch_table)
{
int x;
for (x=0; x<SCREENWIDTH; ++x)
{
*dest = stretch_table[*src1 * 256 + *src2];
++dest;
++src1;
++src2;
}
}
void I_Stretch1x(int x1, int y1, int x2, int y2)
{
byte *bufp, *screenp;
int y;
// Only works with full screen update
if (x1 != 0 || y1 != 0 || x2 != SCREENWIDTH || y2 != SCREENHEIGHT)
{
return;
}
// Need to byte-copy from buffer into the screen buffer
bufp = src_buffer + y1 * SCREENWIDTH + x1;
screenp = (byte *) dest_buffer + y1 * dest_pitch + x1;
// For every 5 lines of src_buffer, 6 lines are written to dest_buffer
// (200 -> 240)
for (y=0; y<SCREENHEIGHT; y += 5)
{
// 100% line 0
memcpy(screenp, bufp, SCREENWIDTH);
screenp += dest_pitch;
// 20% line 0, 80% line 1
WriteBlendedLine1x(screenp, bufp, bufp + SCREENWIDTH, stretch_tables[0]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 40% line 1, 60% line 2
WriteBlendedLine1x(screenp, bufp, bufp + SCREENWIDTH, stretch_tables[1]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 60% line 2, 40% line 3
WriteBlendedLine1x(screenp, bufp + SCREENWIDTH, bufp, stretch_tables[1]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 80% line 3, 20% line 4
WriteBlendedLine1x(screenp, bufp + SCREENWIDTH, bufp, stretch_tables[0]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 100% line 4
memcpy(screenp, bufp, SCREENWIDTH);
screenp += dest_pitch; bufp += SCREENWIDTH;
}
}
static void WriteLine2x(byte *dest, byte *src)
{
int x;
for (x=0; x<SCREENWIDTH; ++x)
{
dest[0] = *src;
dest[1] = *src;
dest += 2;
++src;
}
}
static void WriteBlendedLine2x(byte *dest, byte *src1, byte *src2,
byte *stretch_table)
{
int x;
int val;
for (x=0; x<SCREENWIDTH; ++x)
{
val = stretch_table[*src1 * 256 + *src2];
dest[0] = val;
dest[1] = val;
dest += 2;
++src1;
++src2;
}
}
// Scale 2x, correcting aspect ratio in the process
void I_Stretch2x(int x1, int y1, int x2, int y2)
{
byte *bufp, *screenp;
int y;
// Only works with full screen update
if (x1 != 0 || y1 != 0 || x2 != SCREENWIDTH || y2 != SCREENHEIGHT)
{
return;
}
// Need to byte-copy from buffer into the screen buffer
bufp = src_buffer + y1 * SCREENWIDTH + x1;
screenp = (byte *) dest_buffer + y1 * dest_pitch + x1;
// For every 5 lines of src_buffer, 12 lines are written to dest_buffer.
// (200 -> 480)
for (y=0; y<SCREENHEIGHT; y += 5)
{
// 100% line 0
WriteLine2x(screenp, bufp);
screenp += dest_pitch;
// 100% line 0
WriteLine2x(screenp, bufp);
screenp += dest_pitch;
// 40% line 0, 60% line 1
WriteBlendedLine2x(screenp, bufp, bufp + SCREENWIDTH, stretch_tables[1]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 100% line 1
WriteLine2x(screenp, bufp);
screenp += dest_pitch;
// 80% line 1, 20% line 2
WriteBlendedLine2x(screenp, bufp + SCREENWIDTH, bufp, stretch_tables[0]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 100% line 2
WriteLine2x(screenp, bufp);
screenp += dest_pitch;
// 100% line 2
WriteLine2x(screenp, bufp);
screenp += dest_pitch;
// 20% line 2, 80% line 3
WriteBlendedLine2x(screenp, bufp, bufp + SCREENWIDTH, stretch_tables[0]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 100% line 3
WriteLine2x(screenp, bufp);
screenp += dest_pitch;
// 60% line 3, 40% line 4
WriteBlendedLine2x(screenp, bufp + SCREENWIDTH, bufp, stretch_tables[1]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 100% line 4
WriteLine2x(screenp, bufp);
screenp += dest_pitch;
// 100% line 4
WriteLine2x(screenp, bufp);
screenp += dest_pitch; bufp += SCREENWIDTH;
}
}
static void WriteLine3x(byte *dest, byte *src)
{
int x;
for (x=0; x<SCREENWIDTH; ++x)
{
dest[0] = *src;
dest[1] = *src;
dest[2] = *src;
dest += 3;
++src;
}
}
static void WriteBlendedLine3x(byte *dest, byte *src1, byte *src2,
byte *stretch_table)
{
int x;
int val;
for (x=0; x<SCREENWIDTH; ++x)
{
val = stretch_table[*src1 * 256 + *src2];
dest[0] = val;
dest[1] = val;
dest[2] = val;
dest += 3;
++src1;
++src2;
}
}
void I_Stretch3x(int x1, int y1, int x2, int y2)
{
byte *bufp, *screenp;
int y;
// Only works with full screen update
if (x1 != 0 || y1 != 0 || x2 != SCREENWIDTH || y2 != SCREENHEIGHT)
{
return;
}
// Need to byte-copy from buffer into the screen buffer
bufp = src_buffer + y1 * SCREENWIDTH + x1;
screenp = (byte *) dest_buffer + y1 * dest_pitch + x1;
// For every 5 lines of src_buffer, 18 lines are written to dest_buffer.
// (200 -> 720)
for (y=0; y<SCREENHEIGHT; y += 5)
{
// 100% line 0
WriteLine3x(screenp, bufp);
screenp += dest_pitch;
// 100% line 0
WriteLine3x(screenp, bufp);
screenp += dest_pitch;
// 100% line 0
WriteLine3x(screenp, bufp);
screenp += dest_pitch;
// 60% line 0, 40% line 1
WriteBlendedLine3x(screenp, bufp + SCREENWIDTH, bufp, stretch_tables[1]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 100% line 1
WriteLine3x(screenp, bufp);
screenp += dest_pitch;
// 100% line 1
WriteLine3x(screenp, bufp);
screenp += dest_pitch;
// 100% line 1
WriteLine3x(screenp, bufp);
screenp += dest_pitch;
// 20% line 1, 80% line 2
WriteBlendedLine3x(screenp, bufp, bufp + SCREENWIDTH, stretch_tables[0]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 100% line 2
WriteLine3x(screenp, bufp);
screenp += dest_pitch;
// 100% line 2
WriteLine3x(screenp, bufp);
screenp += dest_pitch;
// 80% line 2, 20% line 3
WriteBlendedLine3x(screenp, bufp + SCREENWIDTH, bufp, stretch_tables[0]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 100% line 3
WriteLine3x(screenp, bufp);
screenp += dest_pitch;
// 100% line 3
WriteLine3x(screenp, bufp);
screenp += dest_pitch;
// 100% line 3
WriteLine3x(screenp, bufp);
screenp += dest_pitch;
// 40% line 3, 60% line 4
WriteBlendedLine3x(screenp, bufp, bufp + SCREENWIDTH, stretch_tables[1]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 100% line 4
WriteLine3x(screenp, bufp);
screenp += dest_pitch;
// 100% line 4
WriteLine3x(screenp, bufp);
screenp += dest_pitch;
// 100% line 4
WriteLine3x(screenp, bufp);
screenp += dest_pitch; bufp += SCREENWIDTH;
}
}
static void WriteLine4x(byte *dest, byte *src)
{
int x;
for (x=0; x<SCREENWIDTH; ++x)
{
dest[0] = *src;
dest[1] = *src;
dest[2] = *src;
dest[3] = *src;
dest += 4;
++src;
}
}
static void WriteBlendedLine4x(byte *dest, byte *src1, byte *src2,
byte *stretch_table)
{
int x;
int val;
for (x=0; x<SCREENWIDTH; ++x)
{
val = stretch_table[*src1 * 256 + *src2];
dest[0] = val;
dest[1] = val;
dest[2] = val;
dest[3] = val;
dest += 4;
++src1;
++src2;
}
}
void I_Stretch4x(int x1, int y1, int x2, int y2)
{
byte *bufp, *screenp;
int y;
// Only works with full screen update
if (x1 != 0 || y1 != 0 || x2 != SCREENWIDTH || y2 != SCREENHEIGHT)
{
return;
}
// Need to byte-copy from buffer into the screen buffer
bufp = src_buffer + y1 * SCREENWIDTH + x1;
screenp = (byte *) dest_buffer + y1 * dest_pitch + x1;
// For every 5 lines of src_buffer, 24 lines are written to dest_buffer.
// (200 -> 960)
for (y=0; y<SCREENHEIGHT; y += 5)
{
// 100% line 0
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 0
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 0
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 0
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 90% line 0, 20% line 1
WriteBlendedLine4x(screenp, bufp + SCREENWIDTH, bufp, stretch_tables[0]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 100% line 1
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 1
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 1
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 1
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 60% line 1, 40% line 2
WriteBlendedLine4x(screenp, bufp + SCREENWIDTH, bufp, stretch_tables[1]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 100% line 2
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 2
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 2
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 2
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 40% line 2, 60% line 3
WriteBlendedLine4x(screenp, bufp, bufp + SCREENWIDTH, stretch_tables[1]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 100% line 3
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 3
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 3
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 3
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 20% line 3, 80% line 4
WriteBlendedLine4x(screenp, bufp, bufp + SCREENWIDTH, stretch_tables[0]);
screenp += dest_pitch; bufp += SCREENWIDTH;
// 100% line 4
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 4
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 4
WriteLine4x(screenp, bufp);
screenp += dest_pitch;
// 100% line 4
WriteLine4x(screenp, bufp);
screenp += dest_pitch; bufp += SCREENWIDTH;
}
}