gl_light.c

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

	int			i;
	int			smax, tmax;
	mtexinfo_t	*tex;
	dlight_t	*dl;
	float		*pfBL;
	float		fsacc, ftacc;

	smax = (surf->extents[0]>>4)+1;
	tmax = (surf->extents[1]>>4)+1;
	tex = surf->texinfo;

	for (lnum=0 ; lnum<r_newrefdef.num_dlights ; lnum++)
	{
		if ( !(surf->dlightbits & (1<<lnum) ) )
			continue;		// not lit by this light

		dl = &r_newrefdef.dlights[lnum];
		frad = dl->intensity;
		fdist = DotProduct (dl->origin, surf->plane->normal) -
				surf->plane->dist;
		frad -= fabs(fdist);
		// rad is now the highest intensity on the plane

		fminlight = DLIGHT_CUTOFF;	// FIXME: make configurable?
		if (frad < fminlight)
			continue;
		fminlight = frad - fminlight;

		for (i=0 ; i<3 ; i++)
		{
			impact[i] = dl->origin[i] -
					surf->plane->normal[i]*fdist;
		}

		local[0] = DotProduct (impact, tex->vecs[0]) + tex->vecs[0][3] - surf->texturemins[0];
		local[1] = DotProduct (impact, tex->vecs[1]) + tex->vecs[1][3] - surf->texturemins[1];

		pfBL = s_blocklights;
		for (t = 0, ftacc = 0 ; t<tmax ; t++, ftacc += 16)
		{
			td = local[1] - ftacc;
			if ( td < 0 )
				td = -td;

			for ( s=0, fsacc = 0 ; s<smax ; s++, fsacc += 16, pfBL += 3)
			{
				sd = Q_ftol( local[0] - fsacc );

				if ( sd < 0 )
					sd = -sd;

				if (sd > td)
					fdist = sd + (td>>1);
				else
					fdist = td + (sd>>1);

				if ( fdist < fminlight )
				{
					pfBL[0] += ( frad - fdist ) * dl->color[0];
					pfBL[1] += ( frad - fdist ) * dl->color[1];
					pfBL[2] += ( frad - fdist ) * dl->color[2];
				}
			}
		}
	}
}


/*
** R_SetCacheState
*/
void R_SetCacheState( msurface_t *surf )
{
	int maps;

	for (maps = 0 ; maps < MAXLIGHTMAPS && surf->styles[maps] != 255 ;
		 maps++)
	{
		surf->cached_light[maps] = r_newrefdef.lightstyles[surf->styles[maps]].white;
	}
}

/*
===============
R_BuildLightMap

Combine and scale multiple lightmaps into the floating format in blocklights
===============
*/
void R_BuildLightMap (msurface_t *surf, byte *dest, int stride)
{
	int			smax, tmax;
	int			r, g, b, a, max;
	int			i, j, size;
	byte		*lightmap;
	float		scale[4];
	int			nummaps;
	float		*bl;
	lightstyle_t	*style;
	int monolightmap;

	if ( surf->texinfo->flags & (SURF_SKY|SURF_TRANS33|SURF_TRANS66|SURF_WARP) )
		ri.Sys_Error (ERR_DROP, "R_BuildLightMap called for non-lit surface");

	smax = (surf->extents[0]>>4)+1;
	tmax = (surf->extents[1]>>4)+1;
	size = smax*tmax;
	if (size > (sizeof(s_blocklights)>>4) )
		ri.Sys_Error (ERR_DROP, "Bad s_blocklights size");

// set to full bright if no light data
	if (!surf->samples)
	{
		int maps;

		for (i=0 ; i<size*3 ; i++)
			s_blocklights[i] = 255;
		for (maps = 0 ; maps < MAXLIGHTMAPS && surf->styles[maps] != 255 ;
			 maps++)
		{
			style = &r_newrefdef.lightstyles[surf->styles[maps]];
		}
		goto store;
	}

	// count the # of maps
	for ( nummaps = 0 ; nummaps < MAXLIGHTMAPS && surf->styles[nummaps] != 255 ;
		 nummaps++)
		;

	lightmap = surf->samples;

	// add all the lightmaps
	if ( nummaps == 1 )
	{
		int maps;

		for (maps = 0 ; maps < MAXLIGHTMAPS && surf->styles[maps] != 255 ;
			 maps++)
		{
			bl = s_blocklights;

			for (i=0 ; i<3 ; i++)
				scale[i] = gl_modulate->value*r_newrefdef.lightstyles[surf->styles[maps]].rgb[i];

			if ( scale[0] == 1.0F &&
				 scale[1] == 1.0F &&
				 scale[2] == 1.0F )
			{
				for (i=0 ; i<size ; i++, bl+=3)
				{
					bl[0] = lightmap[i*3+0];
					bl[1] = lightmap[i*3+1];
					bl[2] = lightmap[i*3+2];
				}
			}
			else
			{
				for (i=0 ; i<size ; i++, bl+=3)
				{
					bl[0] = lightmap[i*3+0] * scale[0];
					bl[1] = lightmap[i*3+1] * scale[1];
					bl[2] = lightmap[i*3+2] * scale[2];
				}
			}
			lightmap += size*3;		// skip to next lightmap
		}
	}
	else
	{
		int maps;

		memset( s_blocklights, 0, sizeof( s_blocklights[0] ) * size * 3 );

		for (maps = 0 ; maps < MAXLIGHTMAPS && surf->styles[maps] != 255 ;
			 maps++)
		{
			bl = s_blocklights;

			for (i=0 ; i<3 ; i++)
				scale[i] = gl_modulate->value*r_newrefdef.lightstyles[surf->styles[maps]].rgb[i];

			if ( scale[0] == 1.0F &&
				 scale[1] == 1.0F &&
				 scale[2] == 1.0F )
			{
				for (i=0 ; i<size ; i++, bl+=3 )
				{
					bl[0] += lightmap[i*3+0];
					bl[1] += lightmap[i*3+1];
					bl[2] += lightmap[i*3+2];
				}
			}
			else
			{
				for (i=0 ; i<size ; i++, bl+=3)
				{
					bl[0] += lightmap[i*3+0] * scale[0];
					bl[1] += lightmap[i*3+1] * scale[1];
					bl[2] += lightmap[i*3+2] * scale[2];
				}
			}
			lightmap += size*3;		// skip to next lightmap
		}
	}

// add all the dynamic lights
	if (surf->dlightframe == r_framecount)
		R_AddDynamicLights (surf);

// put into texture format
store:
	stride -= (smax<<2);
	bl = s_blocklights;

	monolightmap = gl_monolightmap->string[0];

	if ( monolightmap == '0' )
	{
		for (i=0 ; i<tmax ; i++, dest += stride)
		{
			for (j=0 ; j<smax ; j++)
			{
				
				r = Q_ftol( bl[0] );
				g = Q_ftol( bl[1] );
				b = Q_ftol( bl[2] );

				// catch negative lights
				if (r < 0)
					r = 0;
				if (g < 0)
					g = 0;
				if (b < 0)
					b = 0;

				/*
				** determine the brightest of the three color components
				*/
				if (r > g)
					max = r;
				else
					max = g;
				if (b > max)
					max = b;

				/*
				** alpha is ONLY used for the mono lightmap case.  For this reason
				** we set it to the brightest of the color components so that 
				** things don't get too dim.
				*/
				a = max;

				/*
				** rescale all the color components if the intensity of the greatest
				** channel exceeds 1.0
				*/
				if (max > 255)
				{
					float t = 255.0F / max;

					r = r*t;
					g = g*t;
					b = b*t;
					a = a*t;
				}

				dest[0] = r;
				dest[1] = g;
				dest[2] = b;
				dest[3] = a;

				bl += 3;
				dest += 4;
			}
		}
	}
	else
	{
		for (i=0 ; i<tmax ; i++, dest += stride)
		{
			for (j=0 ; j<smax ; j++)
			{
				
				r = Q_ftol( bl[0] );
				g = Q_ftol( bl[1] );
				b = Q_ftol( bl[2] );

				// catch negative lights
				if (r < 0)
					r = 0;
				if (g < 0)
					g = 0;
				if (b < 0)
					b = 0;

				/*
				** determine the brightest of the three color components
				*/
				if (r > g)
					max = r;
				else
					max = g;
				if (b > max)
					max = b;

				/*
				** alpha is ONLY used for the mono lightmap case.  For this reason
				** we set it to the brightest of the color components so that 
				** things don't get too dim.
				*/
				a = max;

				/*
				** rescale all the color components if the intensity of the greatest
				** channel exceeds 1.0
				*/
				if (max > 255)
				{
					float t = 255.0F / max;

					r = r*t;
					g = g*t;
					b = b*t;
					a = a*t;
				}

				/*
				** So if we are doing alpha lightmaps we need to set the R, G, and B
				** components to 0 and we need to set alpha to 1-alpha.
				*/
				switch ( monolightmap )
				{
				case 'L':
				case 'I':
					r = a;
					g = b = 0;
					break;
				case 'C':
					// try faking colored lighting
					a = 255 - ((r+g+b)/3);
					r *= a/255.0;
					g *= a/255.0;
					b *= a/255.0;
					break;
				case 'A':
				default:
					r = g = b = 0;
					a = 255 - a;
					break;
				}

				dest[0] = r;
				dest[1] = g;
				dest[2] = b;
				dest[3] = a;

				bl += 3;
				dest += 4;
			}
		}
	}
}