r_poly.c

Quake 2 Source code for students by Theerthan You can also download from idsoftwares.com

		if (vnext > r_refdef.fvrectbottom_adj)
			vnext = r_refdef.fvrectbottom_adj;

		vbottom = ceil (vnext);

		if (vtop < vbottom)
		{
			uvert = pvert->u;
			if (uvert < r_refdef.fvrectx_adj)
				uvert = r_refdef.fvrectx_adj;
			if (uvert > r_refdef.fvrectright_adj)
				uvert = r_refdef.fvrectright_adj;

			unext = pnext->u;
			if (unext < r_refdef.fvrectx_adj)
				unext = r_refdef.fvrectx_adj;
			if (unext > r_refdef.fvrectright_adj)
				unext = r_refdef.fvrectright_adj;

			du = unext - uvert;
			dv = vnext - vvert;
			slope = du / dv;
			u_step = (int)(slope * 0x10000);
		// adjust u to ceil the integer portion
			u = (int)((uvert + (slope * (vtop - vvert))) * 0x10000) +
					(0x10000 - 1);
			itop = (int)vtop;
			ibottom = (int)vbottom;

			for (v=itop ; v<ibottom ; v++)
			{
				pspan->count = (u >> 16) - pspan->u;
				u += u_step;
				pspan++;
			}
		}

		vtop = vbottom;
		vvert = vnext;

		i++;
		if (i == r_polydesc.nump)
			i = 0;

	} while (i != s_maxindex);

	pspan->count = DS_SPAN_LIST_END;	// mark the end of the span list 
}

/*
** R_ClipAndDrawPoly
*/
// PGM - isturbulent was qboolean. changed to int to allow passing more flags
void R_ClipAndDrawPoly ( float alpha, int isturbulent, qboolean textured )
{
	emitpoint_t	outverts[MAXWORKINGVERTS+3], *pout;
	float		*pv;
	int			i, nump;
	float		scale;
	vec3_t		transformed, local;

	if ( !textured )
	{
		r_polydesc.drawspanlet = R_DrawSpanletConstant33;
	}
	else
	{

		/*
		** choose the correct spanlet routine based on alpha
		*/
		if ( alpha == 1 )
		{
			// isturbulent is ignored because we know that turbulent surfaces
			// can't be opaque
			r_polydesc.drawspanlet = R_DrawSpanletOpaque;
		}
		else
		{
			if ( sw_stipplealpha->value )
			{
				if ( isturbulent )
				{
					if ( alpha > 0.33 )
						r_polydesc.drawspanlet = R_DrawSpanletTurbulentStipple66;
					else 
						r_polydesc.drawspanlet = R_DrawSpanletTurbulentStipple33;
				}
				else
				{
					if ( alpha > 0.33 )
						r_polydesc.drawspanlet = R_DrawSpanlet66Stipple;
					else 
						r_polydesc.drawspanlet = R_DrawSpanlet33Stipple;
				}
			}
			else
			{
				if ( isturbulent )
				{
					if ( alpha > 0.33 )
						r_polydesc.drawspanlet = R_DrawSpanletTurbulentBlended66;
					else
						r_polydesc.drawspanlet = R_DrawSpanletTurbulentBlended33;
				}
				else
				{
					if ( alpha > 0.33 )
						r_polydesc.drawspanlet = R_DrawSpanlet66;
					else 
						r_polydesc.drawspanlet = R_DrawSpanlet33;
				}
			}
		}
	}

	// clip to the frustum in worldspace
	nump = r_polydesc.nump;
	clip_current = 0;

	for (i=0 ; i<4 ; i++)
	{
		nump = R_ClipPolyFace (nump, &view_clipplanes[i]);
		if (nump < 3)
			return;
		if (nump > MAXWORKINGVERTS)
			ri.Sys_Error(ERR_DROP, "R_ClipAndDrawPoly: too many points: %d", nump );
	}

// transform vertices into viewspace and project
	pv = &r_clip_verts[clip_current][0][0];

	for (i=0 ; i<nump ; i++)
	{
		VectorSubtract (pv, r_origin, local);
		TransformVector (local, transformed);

		if (transformed[2] < NEAR_CLIP)
			transformed[2] = NEAR_CLIP;

		pout = &outverts[i];
		pout->zi = 1.0 / transformed[2];

		pout->s = pv[3];
		pout->t = pv[4];
		
		scale = xscale * pout->zi;
		pout->u = (xcenter + scale * transformed[0]);

		scale = yscale * pout->zi;
		pout->v = (ycenter - scale * transformed[1]);

		pv += sizeof (vec5_t) / sizeof (pv);
	}

// draw it
	r_polydesc.nump = nump;
	r_polydesc.pverts = outverts;

	R_DrawPoly( isturbulent );
}

/*
** R_BuildPolygonFromSurface
*/
void R_BuildPolygonFromSurface(msurface_t *fa)
{
	int			i, lindex, lnumverts;
	medge_t		*pedges, *r_pedge;
	int			vertpage;
	float		*vec;
	vec5_t     *pverts;
	float       tmins[2] = { 0, 0 };

	r_polydesc.nump = 0;

	// reconstruct the polygon
	pedges = currentmodel->edges;
	lnumverts = fa->numedges;
	vertpage = 0;

	pverts = r_clip_verts[0];

	for (i=0 ; i<lnumverts ; i++)
	{
		lindex = currentmodel->surfedges[fa->firstedge + i];

		if (lindex > 0)
		{
			r_pedge = &pedges[lindex];
			vec = currentmodel->vertexes[r_pedge->v[0]].position;
		}
		else
		{
			r_pedge = &pedges[-lindex];
			vec = currentmodel->vertexes[r_pedge->v[1]].position;
		}

		VectorCopy (vec, pverts[i] );
	}

	VectorCopy( fa->texinfo->vecs[0], r_polydesc.vright );
	VectorCopy( fa->texinfo->vecs[1], r_polydesc.vup );
	VectorCopy( fa->plane->normal, r_polydesc.vpn );
	VectorCopy( r_origin, r_polydesc.viewer_position );

	if ( fa->flags & SURF_PLANEBACK )
	{
		VectorSubtract( vec3_origin, r_polydesc.vpn, r_polydesc.vpn );
	}

// PGM 09/16/98
	if ( fa->texinfo->flags & (SURF_WARP|SURF_FLOWING) )
	{
		r_polydesc.pixels       = fa->texinfo->image->pixels[0];
		r_polydesc.pixel_width  = fa->texinfo->image->width;
		r_polydesc.pixel_height = fa->texinfo->image->height;
	}
// PGM 09/16/98
	else
	{
		surfcache_t *scache;

		scache = D_CacheSurface( fa, 0 );

		r_polydesc.pixels       = scache->data;
		r_polydesc.pixel_width  = scache->width;
		r_polydesc.pixel_height = scache->height;

		tmins[0] = fa->texturemins[0];
		tmins[1] = fa->texturemins[1];
	}

	r_polydesc.dist = DotProduct( r_polydesc.vpn, pverts[0] );

	r_polydesc.s_offset = fa->texinfo->vecs[0][3] - tmins[0];
	r_polydesc.t_offset = fa->texinfo->vecs[1][3] - tmins[1];

	// scrolling texture addition
	if (fa->texinfo->flags & SURF_FLOWING)
	{
		r_polydesc.s_offset += -128 * ( (r_newrefdef.time*0.25) - (int)(r_newrefdef.time*0.25) );
	}

	r_polydesc.nump = lnumverts;
}

/*
** R_PolygonCalculateGradients
*/
void R_PolygonCalculateGradients (void)
{
	vec3_t		p_normal, p_saxis, p_taxis;
	float		distinv;

	TransformVector (r_polydesc.vpn, p_normal);
	TransformVector (r_polydesc.vright, p_saxis);
	TransformVector (r_polydesc.vup, p_taxis);

	distinv = 1.0 / (-(DotProduct (r_polydesc.viewer_position, r_polydesc.vpn)) + r_polydesc.dist );

	d_sdivzstepu  =  p_saxis[0] * xscaleinv;
	d_sdivzstepv  = -p_saxis[1] * yscaleinv;
	d_sdivzorigin =  p_saxis[2] - xcenter * d_sdivzstepu - ycenter * d_sdivzstepv;

	d_tdivzstepu  =  p_taxis[0] * xscaleinv;
	d_tdivzstepv  = -p_taxis[1] * yscaleinv;
	d_tdivzorigin =  p_taxis[2] - xcenter * d_tdivzstepu - ycenter * d_tdivzstepv;

	d_zistepu =   p_normal[0] * xscaleinv * distinv;
	d_zistepv =  -p_normal[1] * yscaleinv * distinv;
	d_ziorigin =  p_normal[2] * distinv - xcenter * d_zistepu - ycenter * d_zistepv;

	sadjust = (fixed16_t) ( ( DotProduct( r_polydesc.viewer_position, r_polydesc.vright) + r_polydesc.s_offset ) * 0x10000 );
	tadjust = (fixed16_t) ( ( DotProduct( r_polydesc.viewer_position, r_polydesc.vup   ) + r_polydesc.t_offset ) * 0x10000 );

// -1 (-epsilon) so we never wander off the edge of the texture
	bbextents = (r_polydesc.pixel_width << 16) - 1;
	bbextentt = (r_polydesc.pixel_height << 16) - 1;
}

/*
** R_DrawPoly
**
** Polygon drawing function.  Uses the polygon described in r_polydesc
** to calculate edges and gradients, then renders the resultant spans.
**
** This should NOT be called externally since it doesn't do clipping!
*/
// PGM - iswater was qboolean. changed to support passing more flags
static void R_DrawPoly( int iswater )
{
	int			i, nump;
	float		ymin, ymax;
	emitpoint_t	*pverts;
	espan_t	spans[MAXHEIGHT+1];

	s_polygon_spans = spans;

// find the top and bottom vertices, and make sure there's at least one scan to
// draw
	ymin = 999999.9;
	ymax = -999999.9;
	pverts = r_polydesc.pverts;

	for (i=0 ; i<r_polydesc.nump ; i++)
	{
		if (pverts->v < ymin)
		{
			ymin = pverts->v;
			s_minindex = i;
		}

		if (pverts->v > ymax)
		{
			ymax = pverts->v;
			s_maxindex = i;
		}

		pverts++;
	}

	ymin = ceil (ymin);
	ymax = ceil (ymax);

	if (ymin >= ymax)
		return;		// doesn't cross any scans at all

	cachewidth = r_polydesc.pixel_width;
	cacheblock = r_polydesc.pixels;

// copy the first vertex to the last vertex, so we don't have to deal with
// wrapping
	nump = r_polydesc.nump;
	pverts = r_polydesc.pverts;
	pverts[nump] = pverts[0];

	R_PolygonCalculateGradients ();
	R_PolygonScanLeftEdge ();
	R_PolygonScanRightEdge ();

	R_PolygonDrawSpans( s_polygon_spans, iswater );
}

/*
** R_DrawAlphaSurfaces
*/
void R_DrawAlphaSurfaces( void )
{
	msurface_t *s = r_alpha_surfaces;

	currentmodel = r_worldmodel;

	modelorg[0] = -r_origin[0];
	modelorg[1] = -r_origin[1];
	modelorg[2] = -r_origin[2];

	while ( s )
	{
		R_BuildPolygonFromSurface( s );

//=======
//PGM
//		if (s->texinfo->flags & SURF_TRANS66)
//			R_ClipAndDrawPoly( 0.60f, ( s->texinfo->flags & SURF_WARP) != 0, true );
//		else
//			R_ClipAndDrawPoly( 0.30f, ( s->texinfo->flags & SURF_WARP) != 0, true );

		// PGM - pass down all the texinfo flags, not just SURF_WARP.
		if (s->texinfo->flags & SURF_TRANS66)
			R_ClipAndDrawPoly( 0.60f, (s->texinfo->flags & SURF_WARP|SURF_FLOWING), true );
		else
			R_ClipAndDrawPoly( 0.30f, (s->texinfo->flags & SURF_WARP|SURF_FLOWING), true );
//PGM
//=======

		s = s->nextalphasurface;
	}
	
	r_alpha_surfaces = NULL;
}

/*
** R_IMFlatShadedQuad
*/
void R_IMFlatShadedQuad( vec3_t a, vec3_t b, vec3_t c, vec3_t d, int color, float alpha )
{
	vec3_t s0, s1;

	r_polydesc.nump = 4;
	VectorCopy( r_origin, r_polydesc.viewer_position );

	VectorCopy( a, r_clip_verts[0][0] );
	VectorCopy( b, r_clip_verts[0][1] );
	VectorCopy( c, r_clip_verts[0][2] );
	VectorCopy( d, r_clip_verts[0][3] );

	r_clip_verts[0][0][3] = 0;
	r_clip_verts[0][1][3] = 0;
	r_clip_verts[0][2][3] = 0;
	r_clip_verts[0][3][3] = 0;

	r_clip_verts[0][0][4] = 0;
	r_clip_verts[0][1][4] = 0;
	r_clip_verts[0][2][4] = 0;
	r_clip_verts[0][3][4] = 0;

	VectorSubtract( d, c, s0 );
	VectorSubtract( c, b, s1 );
	CrossProduct( s0, s1, r_polydesc.vpn );
	VectorNormalize( r_polydesc.vpn );

	r_polydesc.dist = DotProduct( r_polydesc.vpn, r_clip_verts[0][0] );

	r_polyblendcolor = color;

	R_ClipAndDrawPoly( alpha, false, false );
}