Wolf3D-Mac/RefBsp.c

#include "WolfDef.h"

static Word checkcoord[11][4] = {	/* Indexs to the bspcoord table */
{3,0,2,1},
{3,0,2,0},
{3,1,2,0},
{0,0,0,0},
{2,0,2,1},
{0,0,0,0},		/* Not valid */
{3,1,3,0},
{0,0,0,0},
{2,0,3,1},
{2,1,3,1},
{2,1,3,0}};

/**********************************

	Draw a 3-D textured polygon, must be done FAST!
		
**********************************/

void RenderWallLoop(Word x1,Word x2,Word distance)
{
	fixed_t	texturecolumn;
	Word tile,scaler, angle;
	
/* calculate and draw each column */
	
	if (rw_downside) {
		while (x1 < x2) {		/* Time to draw? */
			scaler = rw_scale >> FRACBITS;		/* Get the draw scale */
			xscale[x1] = scaler;		/* Save the scale factor */
			angle = xtoviewangle[x1]+rw_centerangle;
			texturecolumn = rw_midpoint - SUFixedMul(finetangent[angle],distance);	/* Which texture to use? */	
			if ((Word)texturecolumn < rw_mintex) {
				texturecolumn = rw_mintex;
			} else if ((Word)texturecolumn >= rw_maxtex) {
				texturecolumn = rw_maxtex-1;
			}
			tile = rw_texture[texturecolumn>>8];	/* Get the tile to use */
			IO_ScaleWallColumn(x1,scaler,tile,(texturecolumn>>1)&127);	/* Draw the line */
			++x1;						/* Next x */
			rw_scale+=rw_scalestep;		/* Step the scale factor for the wall */
		}
		return;
	}
	while (x1 < x2) {		/* Time to draw? */
		scaler = rw_scale >> FRACBITS;		/* Get the draw scale */
		xscale[x1] = scaler;		/* Save the scale factor */
		angle = xtoviewangle[x1]+rw_centerangle;
		texturecolumn = SUFixedMul(finetangent[angle],distance)+rw_midpoint;	/* Which texture to use? */
		if ((Word)texturecolumn < rw_mintex) {
			texturecolumn = rw_mintex;
		} else if ((Word)texturecolumn >= rw_maxtex) {
			texturecolumn = rw_maxtex-1;
		}
		tile = rw_texture[texturecolumn>>8];	/* Get the tile to use */
		if (!(WallListPtr[tile+1] & 0x4000)) {
			texturecolumn^=0xff;	/* Reverse the tile for N,W walls */
		}
		IO_ScaleWallColumn(x1,scaler,tile,(texturecolumn>>1)&127);	/* Draw the line */
		++x1;						/* Next x */
		rw_scale+=rw_scalestep;		/* Step the scale factor for the wall */
	}
}


/*
=====================
=
= RenderWallRange
=
= Draw a wall segment between start and stop angles (inclusive) (short angles)
= No clipping is needed
=
======================
*/

void RenderWallRange (Word start,Word stop,saveseg_t *seg,Word distance)
{
	LongWord scale2;
	Word vangle;
	Word x1,x2;

/* mark the segment as visible for auto map*/

	seg->dir |= DIR_SEENFLAG;		/* for automap*/
	areavis[seg->area] = 1;			/* for sprite drawing*/
	
	start -= ANGLE180;		/* Adjust the start angle */
	stop -= ANGLE180;		/* Adjust the stop angle */
	vangle = (Word)(start+ANGLE90)>>ANGLETOFINESHIFT;
	x1 = viewangletox[vangle];
	vangle = (Word)(stop+ANGLE90-1)>>ANGLETOFINESHIFT;	/* make non inclusive*/
	x2 = viewangletox[vangle];
	if (x2 == x1) {
		return;		/* less than one column wide*/
	}
	rw_scale = (long) ScaleFromGlobalAngle(start+centershort,distance)<<FRACBITS;
	if (x2>x1+1) {
		scale2 = (long) ScaleFromGlobalAngle(stop+centershort,distance)<<FRACBITS;
		rw_scalestep = (long)(scale2-rw_scale)/(long)(x2-x1);
	}
	RenderWallLoop(x1,x2,distance);
}

/*
===============================================================================
=
= ClipWallSegment
=
= Clips the given screenpost and includes it in newcolumn
===============================================================================
*/

/* a screenpost_t is a solid range of visangles, used to clip and detect*/
/* span exposures / hidings*/

typedef	struct {
	Word top, bottom;
} screenpost_t;

#define	MAXSEGS	16

screenpost_t solidsegs[MAXSEGS], *newend;	/* newend is one past the last valid seg */

void ClipWallSegment(Word top,Word bottom,saveseg_t *seg,Word distance)
{
	screenpost_t *next, *start;
	
/* find the first clippost that touches the source post (adjacent pixels are touching)*/
	start = solidsegs;
	while (start->bottom > top+1) {
		start++;
	}

	if (top > start->top) {
		if (bottom > start->top+1) {	/* post is entirely visible (above start), so insert a new clippost*/
			RenderWallRange(top, bottom,seg,distance);
			next = newend;
			newend++;
			while (next !