r_draw.c

//
// Copyright (C) 1993-1996 Id Software, Inc.
// Copyright (C) 2016-2017 Alexey Khokholov (Nuke.YKT)
// Copyright (C) 2017 Alexandre-Xavier Labonté-Lamoureux
//
// 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.
//
// DESCRIPTION:
//	The actual span/column drawing functions.
//	Here find the main potential for optimization,
//	 e.g. inline assembly, different algorithms.
//


#include <conio.h>
#include "doomdef.h"

#include "i_system.h"
#include "z_zone.h"
#include "w_wad.h"

#include "r_local.h"

// Needs access to LFB (guess what).
#include "v_video.h"

// State.
#include "doomstat.h"


// ?
#define MAXWIDTH			1120
#define MAXHEIGHT			832

// status bar height at bottom of screen
#define SBARHEIGHT		32

//
// All drawing to the view buffer is accomplished in this file.
// The other refresh files only know about ccordinates,
//  not the architecture of the frame buffer.
// Conveniently, the frame buffer is a linear one,
//  and we need only the base address,
//  and the total size == width*height*depth/8.,
//


byte*		viewimage; 
int		viewwidth;
int		scaledviewwidth;
int		viewheight;
int		viewwindowx;
int		viewwindowy; 
byte*		ylookup[MAXHEIGHT]; 
int		columnofs[MAXWIDTH]; 

// Color tables for different players,
//  translate a limited part to another
//  (color ramps used for  suit colors).
//
byte		translations[3][256];	
 
 
#define SC_INDEX                0x3C4
#define SC_RESET                0
#define SC_CLOCK                1
#define SC_MAPMASK              2
#define SC_CHARMAP              3
#define SC_MEMMODE              4

#define GC_INDEX                0x3CE
#define GC_SETRESET             0
#define GC_ENABLESETRESET 1
#define GC_COLORCOMPARE 2
#define GC_DATAROTATE   3
#define GC_READMAP              4
#define GC_MODE                 5
#define GC_MISCELLANEOUS 6
#define GC_COLORDONTCARE 7
#define GC_BITMASK              8

//
// R_DrawColumn
// Source is the top of the column to scale.
//
lighttable_t*		dc_colormap; 
int			dc_x; 
int			dc_yl; 
int			dc_yh; 
fixed_t			dc_iscale; 
fixed_t			dc_texturemid;

// first pixel in a column (possibly virtual) 
byte*			dc_source;		

// just for profiling 
int			dccount;

//
// A column is a vertical slice/span from a wall texture that,
//  given the DOOM style restrictions on the view orientation,
//  will always have constant z depth.
// Thus a special case loop for very fast rendering can
//  be used. It has also been used with Wolfenstein 3D.
// 
void R_DrawColumn (void) 
{ 
    int			count; 
    byte*		dest; 
    fixed_t		frac;
    fixed_t		fracstep;	 
 
    count = dc_yh - dc_yl; 

    // Zero length, column does not exceed a pixel.
    if (count < 0) 
	return; 
				 
#ifdef RANGECHECK 
    if ((unsigned)dc_x >= SCREENWIDTH
	|| dc_yl < 0
	|| dc_yh >= SCREENHEIGHT) 
	I_Error ("R_DrawColumn: %i to %i at %i", dc_yl, dc_yh, dc_x); 
#endif 

        outp (SC_INDEX+1,1<<(dc_x&3)); 

        dest = destview + dc_yl*80 + (dc_x>>2); 

    // Determine scaling,
    //  which is the only mapping to be done.
    fracstep = dc_iscale; 
    frac = dc_texturemid + (dc_yl-centery)*fracstep; 

    // Inner loop that does the actual texture mapping,
    //  e.g. a DDA-lile scaling.
    // This is as fast as it gets.
    do 
    {
	// Re-map color indices from wall texture column
	//  using a lighting/special effects LUT.
	*dest = dc_colormap[dc_source[(frac>>FRACBITS)&127]];
	
	dest += SCREENWIDTH/4;
	frac += fracstep;
	
    } while (count--); 
} 



void R_DrawColumnLow (void) 
{ 
    int			count; 
    byte*		dest; 
    fixed_t		frac;
    fixed_t		fracstep;	 
 
    count = dc_yh - dc_yl; 

    // Zero length.
    if (count < 0) 
	return; 
				 
#ifdef RANGECHECK 
    if ((unsigned)dc_x >= SCREENWIDTH
	|| dc_yl < 0
	|| dc_yh >= SCREENHEIGHT)
    {
	
	I_Error ("R_DrawColumn: %i to %i at %i", dc_yl, dc_yh, dc_x);
    }
    //	dccount++; 
#endif 
        if (dc_x & 1)
            outp (SC_INDEX+1,12); 
        else
            outp (SC_INDEX+1,3);

        dest = destview + dc_yl*80 + (dc_x>>1); 
    
    fracstep = dc_iscale; 
    frac = dc_texturemid + (dc_yl-centery)*fracstep;
    
    do 
    {
        *dest = dc_colormap[dc_source[(frac>>FRACBITS)&127]];
        
        dest += SCREENWIDTH/4; 
        frac += fracstep;

    } while (count--);
}


//
// Spectre/Invisibility.
//
#define FUZZTABLE		50 
#define FUZZOFF	(SCREENWIDTH/4)


int	fuzzoffset[FUZZTABLE] =
{
    FUZZOFF,-FUZZOFF,FUZZOFF,-FUZZOFF,FUZZOFF,FUZZOFF,-FUZZOFF,
    FUZZOFF,FUZZOFF,-FUZZOFF,FUZZOFF,FUZZOFF,FUZZOFF,-FUZZOFF,
    FUZZOFF,FUZZOFF,FUZZOFF,-FUZZOFF,-FUZZOFF,-FUZZOFF,-FUZZOFF,
    FUZZOFF,-FUZZOFF,-FUZZOFF,FUZZOFF,FUZZOFF,FUZZOFF,FUZZOFF,-FUZZOFF,
    FUZZOFF,-FUZZOFF,FUZZOFF,FUZZOFF,-FUZZOFF,-FUZZOFF,FUZZOFF,
    FUZZOFF,-FUZZOFF,-FUZZOFF,-FUZZOFF,-FUZZOFF,FUZZOFF,FUZZOFF,
    FUZZOFF,FUZZOFF,-FUZZOFF,FUZZOFF,FUZZOFF,-FUZZOFF,FUZZOFF 
}; 

int	fuzzpos = 0; 


//
// Framebuffer postprocessing.
// Creates a fuzzy image by copying pixels
//  from adjacent ones to left and right.
// Used with an all black colormap, this
//  could create the SHADOW effect,
//  i.e. spectres and invisible players.
//
void R_DrawFuzzColumn (void) 
{ 
    int			count; 
    byte*		dest; 
    fixed_t		frac;
    fixed_t		fracstep;	 

    // Adjust borders. Low... 
    if (!dc_yl) 
	dc_yl = 1;

    // .. and high.
    if (dc_yh == viewheight-1) 
	dc_yh = viewheight - 2; 
		 
    count = dc_yh - dc_yl; 

    // Zero length.
    if (count < 0) 
	return; 

    
#ifdef RANGECHECK 
    if ((unsigned)dc_x >= SCREENWIDTH
	|| dc_yl < 0 || dc_yh >= SCREENHEIGHT)
    {
	I_Error ("R_DrawFuzzColumn: %i to %i at %i",
		 dc_yl, dc_yh, dc_x);
    }
#endif

    if (detailshift)
    {
	if (dc_x & 1)
	{
	    outpw (GC_INDEX,GC_READMAP+(2<<8) ); 
	    outp (SC_INDEX+1,12); 
	}
	else
	{
	    outpw (GC_INDEX,GC_READMAP); 
	    outp (SC_INDEX+1,3); 
	}
	dest = destview + dc_yl*80 + (dc_x>>1); 
    }
    else
    {
	outpw (GC_INDEX,GC_READMAP+((dc_x&3)<<8) ); 
	outp (SC_INDEX+1,1<<(dc_x&3)); 
	dest = destview + dc_yl*80 + (dc_x>>2); 
    }

    // Looks familiar.
    fracstep = dc_iscale; 
    frac = dc_texturemid + (dc_yl-centery)*fracstep; 

    // Looks like an attempt at dithering,
    //  using the colormap #6 (of 0-31, a bit
    //  brighter than average).
    do 
    {
	// Lookup framebuffer, and retrieve
	//  a pixel that is either one column
	//  left or right of the current one.
	// Add index from colormap to index.
	*dest = colormaps[6*256+dest[fuzzoffset[fuzzpos]]]; 

	// Clamp table lookup index.
	if (++fuzzpos == FUZZTABLE) 
	    fuzzpos = 0;
	
	dest += SCREENWIDTH/4;

	frac += fracstep; 
    } while (count--); 
} 
 
  
 

//
// R_DrawTranslatedColumn
// Used to draw player sprites
//  with the green colorramp mapped to others.
// Could be used with different translation
//  tables, e.g. the lighter colored version
//  of the BaronOfHell, the HellKnight, uses
//  identical sprites, kinda brightened up.
//
byte*	dc_translation;
byte*	translationtables;

void R_DrawTranslatedColumn (void) 
{ 
    int			count; 
    byte*		dest; 
    fixed_t		frac;
    fixed_t		fracstep;	 
 
    count = dc_yh - dc_yl; 
    if (count < 0) 
	return; 
				 
#ifdef RANGECHECK 
    if ((unsigned)dc_x >= SCREENWIDTH
	|| dc_yl < 0
	|| dc_yh >= SCREENHEIGHT)
    {
	I_Error ( "R_DrawColumn: %i to %i at %i",
		  dc_yl, dc_yh, dc_x);
    }
    
#endif 


    if (detailshift)
    {
	if (dc_x & 1)
	    outp (SC_INDEX+1,12); 
	else
	    outp (SC_INDEX+1,3);
	
	dest = destview + dc_yl*80 + (dc_x>>1); 
    }
    else
    {
	outp (SC_INDEX+1,1<<(dc_x&3)); 

	dest = destview + dc_yl*80 + (dc_x>>2); 
    }

    // Looks familiar.
    fracstep = dc_iscale; 
    frac = dc_texturemid + (dc_yl-centery)*fracstep; 

    // Here we do an additional index re-mapping.
    do 
    {
	// Translation tables are used
	//  to map certain colorramps to other ones,
	//  used with PLAY sprites.
	// Thus the "green" ramp of the player 0 sprite
	//  is mapped to gray, red, black/indigo. 
	*dest = dc_colormap[dc_translation[dc_source[frac>>FRACBITS]]];
	dest += SCREENWIDTH/4;
	
	frac += fracstep; 
    } while (count--); 
} 




//
// R_InitTranslationTables
// Creates the translation tables to map
//  the green color ramp to gray, brown, red.
// Assumes a given structure of the PLAYPAL.
// Could be read from a lump instead.
//
void R_InitTranslationTables (void)
{
    int		i;
	
    translationtables = Z_Malloc (256*3+255, PU_STATIC, 0);
    translationtables = (byte *)(( (int)translationtables + 255 )& ~255);
    
    // translate just the 16 green colors
    for (i=0 ; i<256 ; i++)
    {
	if (i >= 0x70 && i<= 0x7f)
	{
	    // map green ramp to gray, brown, red
	    translationtables[i] = 0x60 + (i&0xf);
	    translationtables [i+256] = 0x40 + (i&0xf);
	    translationtables [i+512] = 0x20 + (i&0xf);
	}
	else
	{
	    // Keep all other colors as is.
	    translationtables[i] = translationtables[i+256] 
		= translationtables[i+512] = i;
	}
    }
}



//
// R_DrawSpan 
// With DOOM style restrictions on view orientation,
//  the floors and ceilings consist of horizontal slices
//  or spans with constant z depth.
// However, rotation around the world z axis is possible,
//  thus this mapping, while simpler and faster than
//  perspective correct texture mapping, has to traverse
//  the texture at an angle in all but a few cases.
// In consequence, flats are not stored by column (like walls),
//  and the inner loop has to step in texture space u and v.
//
int			ds_y; 
int			ds_x1; 
int			ds_x2;

lighttable_t*		ds_colormap; 

fixed_t			ds_xfrac; 
fixed_t			ds_yfrac; 
fixed_t			ds_xstep; 
fixed_t			ds_ystep;

// start of a 64*64 tile image 
byte*			ds_source;	

// just for profiling
int			dscount;


//
// Draws the actual span.
void R_DrawSpan (void) 
{ 
    fixed_t		xfrac;
    fixed_t		yfrac; 
    byte*		dest; 
    int			spot; 
        int                     i;
        int                     prt;
        int                     dsp_x1;
        int                     dsp_x2;
        int                     countp;
         
#ifdef RANGECHECK 
    if (ds_x2 < ds_x1
        || ds_x1<0
        || ds_x2>=SCREENWIDTH  
        || (unsigned)ds_y>SCREENHEIGHT)
    {
        I_Error( "R_DrawSpan: %i to %i at %i",
                 ds_x1,ds_x2,ds_y);
    } 
#endif 

        for (i = 0; i < 4; i++)
        {
                outp (SC_INDEX+1,1<<i); 
                dsp_x1 = (ds_x1-i)/4;
                if (dsp_x1*4+i<ds_x1)
                        dsp_x1++;
                dest = destview + ds_y*80 + dsp_x1;
                dsp_x2 = (ds_x2-i)/4;
                countp = dsp_x2 - dsp_x1;

                xfrac = ds_xfrac; 
                yfrac = ds_yfrac;

                prt = dsp_x1*4-ds_x1+i;

                xfrac += ds_xstep*prt;
                yfrac += ds_ystep*prt;
                if (countp < 0) {
                        continue;
                }
                do
                {
                        // Current texture index in u,v.
                        spot = ((yfrac>>(16-6))&(63*64)) + ((xfrac>>16)&63);

                        // 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*4; 
                        yfrac += ds_ystep*4;
                } while (countp--);
        }
} 



//
// Again..
//
void R_DrawSpanLow (void) 
{ 
    fixed_t		xfrac;
    fixed_t		yfrac; 
    byte*		dest; 
    int			spot; 
        int                     i;
        int                     prt;
        int                     dsp_x1;
        int                     dsp_x2;
        int                     countp;
         
#ifdef RANGECHECK 
    if (ds_x2 < ds_x1
        || ds_x1<0
        || ds_x2>=SCREENWIDTH  
        || (unsigned)ds_y>SCREENHEIGHT)
    {
        I_Error( "R_DrawSpan: %i to %i at %i",
                 ds_x1,ds_x2,ds_y);
    } 
#endif 

        for (i = 0; i < 2; i++)
        {
                outp (SC_INDEX+1,3<<(i*2)); 
                dsp_x1 = (ds_x1-i)/2;
                if (dsp_x1*2+i<ds_x1)
                        dsp_x1++;
                dest = destview + ds_y*80 + dsp_x1;
                dsp_x2 = (ds_x2-i)/2;
                countp = dsp_x2 - dsp_x1;

                xfrac = ds_xfrac; 
                yfrac = ds_yfrac;

                prt = dsp_x1*2-ds_x1+i;

                xfrac += ds_xstep*prt;
                yfrac += ds_ystep*prt;
                if (countp < 0) {
                        continue;
                }
                do
                {
                        // Current texture index in u,v.
                        spot = ((yfrac>>(16-6))&(63*64)) + ((xfrac>>16)&63);

                        // 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*2; 
                        yfrac += ds_ystep*2;
                } while (countp--);
        }
}

//
// R_InitBuffer 
// Creats lookup tables that avoid
//  multiplies and other hazzles
//  for getting the framebuffer address
//  of a pixel to draw.
//
void
R_InitBuffer
( int		width,
  int		height ) 
{ 
    int		i; 

    // Handle resize,
    //  e.g. smaller view windows
    //  with border and/or status bar.
    viewwindowx = (SCREENWIDTH-width) >> 1; 

    // Column offset. For windows.
    for (i=0 ; i<width ; i++) 
	columnofs[i] = viewwindowx + i;

    // Samw with base row offset.
    if (width == SCREENWIDTH) 
	viewwindowy = 0; 
    else 
	viewwindowy = (SCREENHEIGHT-SBARHEIGHT-height) >> 1; 

    // Preclaculate all row offsets.
    for (i=0 ; i<height ; i++) 
	ylookup[i] = screens[0] + (i+viewwindowy)*SCREENWIDTH; 
} 
 
 


//
// R_FillBackScreen
// Fills the back screen with a pattern
//  for variable screen sizes
// Also draws a beveled edge.
//
void R_FillBackScreen (void) 
{ 
    byte*	src;
    byte*	dest; 
    int		x;
    int		y; 
    patch_t*	patch;
    int i;

    // DOOM border patch.
    char	name1[] = "FLOOR7_2";

    // DOOM II border patch.
    char	name2[] = "GRNROCK";	

    char*	name;
	
    if (scaledviewwidth == 320)
	return;
	
    if (commercial)
	name = name2;
    else
	name = name1;
    
    src = W_CacheLumpName (name, PU_CACHE); 
    dest = screens[1]; 
	 
    for (y=0 ; y<SCREENHEIGHT-SBARHEIGHT ; y++) 
    { 
	for (x=0 ; x<SCREENWIDTH/64 ; x++) 
	{ 
	    memcpy (dest, src+((y&63)<<6), 64); 
	    dest += 64; 
	} 

	// Unreachable code?
	if (SCREENWIDTH&63) 
	{ 
	    memcpy (dest, src+((y&63)<<6), SCREENWIDTH&63); 
	    dest += (SCREENWIDTH&63); 
	} 
    } 
	
    patch = W_CacheLumpName ("brdr_t",PU_CACHE);

    for (x=0 ; x<scaledviewwidth ; x+=8)
	V_DrawPatch (viewwindowx+x,viewwindowy-8,1,patch);
    patch = W_CacheLumpName ("brdr_b",PU_CACHE);

    for (x=0 ; x<scaledviewwidth ; x+=8)
	V_DrawPatch (viewwindowx+x,viewwindowy+viewheight,1,patch);
    patch = W_CacheLumpName ("brdr_l",PU_CACHE);

    for (y=0 ; y<viewheight ; y+=8)
	V_DrawPatch (viewwindowx-8,viewwindowy+y,1,patch);
    patch = W_CacheLumpName ("brdr_r",PU_CACHE);

    for (y=0 ; y<viewheight ; y+=8)
	V_DrawPatch (viewwindowx+scaledviewwidth,viewwindowy+y,1,patch);


    // Draw beveled edge. 
    V_DrawPatch (viewwindowx-8,
		 viewwindowy-8,
		 1,
		 W_CacheLumpName ("brdr_tl",PU_CACHE));
    
    V_DrawPatch (viewwindowx+scaledviewwidth,
		 viewwindowy-8,
		 1,
		 W_CacheLumpName ("brdr_tr",PU_CACHE));
    
    V_DrawPatch (viewwindowx-8,
		 viewwindowy+viewheight,
		 1,
		 W_CacheLumpName ("brdr_bl",PU_CACHE));
    
    V_DrawPatch (viewwindowx+scaledviewwidth,
		 viewwindowy+viewheight,
		 1,
		 W_CacheLumpName ("brdr_br",PU_CACHE));

    for (i = 0; i < 4; i++)
    {
        outp(SC_INDEX, SC_MAPMASK);
        outp(SC_INDEX + 1, 1 << i);

        dest = (byte*)0xac000;
        src = screens[1] + i;
        do
        {
            *dest++ = *src;
            src += 4;
        } while (dest != (byte*)(0xac000
                              + (SCREENHEIGHT-SBARHEIGHT)*SCREENWIDTH / 4));
    }
} 
 

//
// Copy a screen buffer.
//
void
R_VideoErase
( unsigned	ofs,
  int		count ) 
{
    byte* dest;
    byte* source;
    int countp;
    outp(SC_INDEX, SC_MAPMASK);
    outp(SC_INDEX + 1, 15);
    outp(GC_INDEX, GC_MODE);
    outp(GC_INDEX + 1, inp(GC_INDEX + 1) | 1);
    dest = destscreen + (ofs >> 2);
    source = (byte*)0xac000 + (ofs >> 2);
    countp = count / 4;
    while (--countp >= 0)
    {
        dest[countp] = source[countp];
    }

    outp(GC_INDEX, GC_MODE);
    outp(GC_INDEX + 1, inp(GC_INDEX + 1)&~1);
} 


//
// R_DrawViewBorder
// Draws the border around the view
//  for different size windows?
//
void
V_MarkRect
( int		x,
  int		y,
  int		width,
  int		height ); 
 
void R_DrawViewBorder (void) 
{ 
    int		top;
    int		side;
    int		ofs;
    int		i; 
 
    if (scaledviewwidth == SCREENWIDTH) 
	return; 
  
    top = ((SCREENHEIGHT-SBARHEIGHT)-viewheight)/2; 
    side = (SCREENWIDTH-scaledviewwidth)/2; 
 
    // copy top and one line of left side 
    R_VideoErase (0, top*SCREENWIDTH+side); 
 
    // copy one line of right side and bottom 
    ofs = (viewheight+top)*SCREENWIDTH-side; 
    R_VideoErase (ofs, top*SCREENWIDTH+side); 
 
    // copy sides using wraparound 
    ofs = top*SCREENWIDTH + SCREENWIDTH-side; 
    side <<= 1;
    
    for (i=1 ; i<viewheight ; i++) 
    { 
	R_VideoErase (ofs, side); 
	ofs += SCREENWIDTH; 
    } 

    // ? 
    //V_MarkRect (0,0,SCREENWIDTH, SCREENHEIGHT-SBARHEIGHT); 
}