r_segs.c

使用Doom引擎开发的著名游戏《毁灭巫师》的源代码。

//**************************************************************************
//**
//** r_segs.c : Heretic 2 : Raven Software, Corp.
//**
//** $RCSfile: r_segs.c,v $
//** $Revision: 1.4 $
//** $Date: 95/08/28 17:02:44 $
//** $Author: cjr $
//**
//** This version has the tall-sector-crossing-precision-bug fixed.
//**
//**************************************************************************

#include "h2def.h"
#include "r_local.h"

// OPTIMIZE: closed two sided lines as single sided

boolean         segtextured;    // true if any of the segs textures might be vis
boolean         markfloor;              // false if the back side is the same plane
boolean         markceiling;
boolean         maskedtexture;
int                     toptexture, bottomtexture, midtexture;


angle_t         rw_normalangle;
int                     rw_angle1;              // angle to line origin

//
// wall
//
int                     rw_x;
int                     rw_stopx;
angle_t         rw_centerangle;
fixed_t         rw_offset;
fixed_t         rw_distance;
fixed_t         rw_scale;
fixed_t         rw_scalestep;
fixed_t         rw_midtexturemid;
fixed_t         rw_toptexturemid;
fixed_t         rw_bottomtexturemid;

int                     worldtop, worldbottom, worldhigh, worldlow;

fixed_t         pixhigh, pixlow;
fixed_t         pixhighstep, pixlowstep;
fixed_t         topfrac, topstep;
fixed_t         bottomfrac, bottomstep;


lighttable_t    **walllights;

short           *maskedtexturecol;

/*
================
=
= R_RenderMaskedSegRange
=
================
*/

void R_RenderMaskedSegRange (drawseg_t *ds, int x1, int x2)
{
	unsigned        index;
	column_t        *col;
	int                     lightnum;
	int                     texnum;

//
// calculate light table
// use different light tables for horizontal / vertical / diagonal
// OPTIMIZE: get rid of LIGHTSEGSHIFT globally
	curline = ds->curline;
	frontsector = curline->frontsector;
	backsector = curline->backsector;
	texnum = texturetranslation[curline->sidedef->midtexture];

	lightnum = (frontsector->lightlevel >> LIGHTSEGSHIFT)+extralight;
	//if (curline->v1->y == curline->v2->y)
	//	lightnum--;
	//else if (curline->v1->x == curline->v2->x)
	//	lightnum++;
	//if (lightnum < 0)
	//	walllights = scalelight[0];
	if (lightnum >= LIGHTLEVELS)
		walllights = scalelight[LIGHTLEVELS-1];
	else
		walllights = scalelight[lightnum];

	maskedtexturecol = ds->maskedtexturecol;

	rw_scalestep = ds->scalestep;
	spryscale = ds->scale1 + (x1 - ds->x1)*rw_scalestep;
	mfloorclip = ds->sprbottomclip;
	mceilingclip = ds->sprtopclip;

//
// find positioning
//
	if (curline->linedef->flags & ML_DONTPEGBOTTOM)
	{
		dc_texturemid = frontsector->floorheight > backsector->floorheight
		? frontsector->floorheight : backsector->floorheight;
		dc_texturemid = dc_texturemid + textureheight[texnum] - viewz;
	}
	else
	{
		dc_texturemid =frontsector->ceilingheight<backsector->ceilingheight
		? frontsector->ceilingheight : backsector->ceilingheight;
		dc_texturemid = dc_texturemid - viewz;
	}
	dc_texturemid += curline->sidedef->rowoffset;

	if (fixedcolormap)
		dc_colormap = fixedcolormap;
//
// draw the columns
//
	for (dc_x = x1 ; dc_x <= x2 ; dc_x++)
	{
	// calculate lighting
		if (maskedtexturecol[dc_x] != MAXSHORT)
		{
			if (!fixedcolormap)
			{
				index = spryscale>>LIGHTSCALESHIFT;
				if (index >=  MAXLIGHTSCALE )
					index = MAXLIGHTSCALE-1;
				dc_colormap = walllights[index];
			}

			sprtopscreen = centeryfrac - FixedMul(dc_texturemid, spryscale);
			dc_iscale = 0xffffffffu / (unsigned)spryscale;

	//
	// draw the texture
	//
			col = (column_t *)(
				(byte *)R_GetColumn(texnum,maskedtexturecol[dc_x]) -3);

			R_DrawMaskedColumn (col, -1);
			maskedtexturecol[dc_x] = MAXSHORT;
		}
		spryscale += rw_scalestep;
	}

}

/*
================
=
= R_RenderSegLoop
=
= Draws zero, one, or two textures (and possibly a masked texture) for walls
= Can draw or mark the starting pixel of floor and ceiling textures
=
= CALLED: CORE LOOPING ROUTINE
================
*/

#define HEIGHTBITS      12
#define HEIGHTUNIT      (1<<HEIGHTBITS)

void R_RenderSegLoop (void)
{
	angle_t         angle;
	unsigned        index;
	int                     yl, yh, mid;
	fixed_t         texturecolumn;
	int                     top, bottom;

//      texturecolumn = 0;                              // shut up compiler warning

	for ( ; rw_x < rw_stopx ; rw_x++)
	{
//
// mark floor / ceiling areas
//
		yl = (topfrac+HEIGHTUNIT-1)>>HEIGHTBITS;
		if (yl < ceilingclip[rw_x]+1)
			yl = ceilingclip[rw_x]+1;       // no space above wall
		if (markceiling)
		{
			top = ceilingclip[rw_x]+1;
			bottom = yl-1;
			if (bottom >= floorclip[rw_x])
				bottom = floorclip[rw_x]-1;
			if (top <= bottom)
			{
				ceilingplane->top[rw_x] = top;
				ceilingplane->bottom[rw_x] = bottom;
			}
		}

		yh = bottomfrac>>HEIGHTBITS;
		if (yh >= floorclip[rw_x])
			yh = floorclip[rw_x]-1;
		if (markfloor)
		{
			top = yh+1;
			bottom = floorclip[rw_x]-1;
			if (top <= ceilingclip[rw_x])
				top = ceilingclip[rw_x]+1;
			if (top <= bottom)
			{
				floorplane->top[rw_x] = top;
				floorplane->bottom[rw_x] = bottom;
			}
		}

//
// texturecolumn and lighting are independent of wall tiers
//
		if (segtextured)
		{
		// calculate texture offset
			angle = (rw_centerangle + xtoviewangle[rw_x])>>ANGLETOFINESHIFT;
			texturecolumn = rw_offset-FixedMul(finetangent[angle],rw_distance);
			texturecolumn >>= FRACBITS;
		// calculate lighting
			index = rw_scale>>LIGHTSCALESHIFT;
			if (index >=  MAXLIGHTSCALE )
				index = MAXLIGHTSCALE-1;
			dc_colormap = walllights[index];
			dc_x = rw_x;
			dc_iscale = 0xffffffffu / (unsigned)rw_scale;
		}

//
// draw the wall tiers
//
		if (midtexture)
		{       // single sided line
			dc_yl = yl;
			dc_yh = yh;
			dc_texturemid = rw_midtexturemid;
			dc_source = R_GetColumn(midtexture,texturecolumn);
			colfunc ();
			ceilingclip[rw_x] = viewheight;
			floorclip[rw_x] = -1;
		}
		else
		{       // two sided line
			if (toptexture)
			{       // top wall
				mid = pixhigh>>HEIGHTBITS;
				pixhigh += pixhighstep;
				if (mid >= floorclip[rw_x])
					mid = floorclip[rw_x]-1;
				if (mid >= yl)
				{
					dc_yl = yl;
					dc_yh = mid;
					dc_texturemid = rw_toptexturemid;
					dc_source = R_GetColumn(toptexture,texturecolumn);
					colfunc ();
					ceilingclip[rw_x] = mid;
				}
				else
					ceilingclip[rw_x] = yl-1;
			}
			else
			{       // no top wall
				if (markceiling)
					ceilingclip[rw_x] = yl-1;
			}

			if (bottomtexture)
			{       // bottom wall
				mid = (pixlow+HEIGHTUNIT-1)>>HEIGHTBITS;
				pixlow += pixlowstep;
				if (mid <= ceilingclip[rw_x])
					mid = ceilingclip[rw_x]+1;      // no space above wall
				if (mid <= yh)
				{
					dc_yl = mid;
					dc_yh = yh;
					dc_texturemid = rw_bottomtexturemid;
					dc_source = R_GetColumn(bottomtexture,
						 texturecolumn);
					colfunc ();
					floorclip[rw_x] = mid;
				}
				else
					floorclip[rw_x] = yh+1;
			}
			else
			{       // no bottom wall
				if (markfloor)
					floorclip[rw_x] = yh+1;
			}

			if (maskedtexture)
			{       // save texturecol for backdrawing of masked mid texture
				maskedtexturecol[rw_x] = texturecolumn;
			}
		}

		rw_scale += rw_scalestep;
		topfrac += topstep;
		bottomfrac += bottomstep;
	}

}



/*
=====================
=
= R_StoreWallRange
=
= A wall segment will be drawn between start and stop pixels (inclusive)
=
======================
*/

void R_StoreWallRange (int start, int stop)
{
	fixed_t         hyp;
	fixed_t         sineval;
	angle_t         distangle, offsetangle;
	fixed_t         vtop;
	int                     lightnum;