gl_image.c

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

=========================================================

TARGA LOADING

=========================================================
*/

typedef struct _TargaHeader {
	unsigned char 	id_length, colormap_type, image_type;
	unsigned short	colormap_index, colormap_length;
	unsigned char	colormap_size;
	unsigned short	x_origin, y_origin, width, height;
	unsigned char	pixel_size, attributes;
} TargaHeader;


/*
=============
LoadTGA
=============
*/
void LoadTGA (char *name, byte **pic, int *width, int *height)
{
	int		columns, rows, numPixels;
	byte	*pixbuf;
	int		row, column;
	byte	*buf_p;
	byte	*buffer;
	int		length;
	TargaHeader		targa_header;
	byte			*targa_rgba;
	byte tmp[2];

	*pic = NULL;

	//
	// load the file
	//
	length = ri.FS_LoadFile (name, (void **)&buffer);
	if (!buffer)
	{
		ri.Con_Printf (PRINT_DEVELOPER, "Bad tga file %s\n", name);
		return;
	}

	buf_p = buffer;

	targa_header.id_length = *buf_p++;
	targa_header.colormap_type = *buf_p++;
	targa_header.image_type = *buf_p++;
	
	tmp[0] = buf_p[0];
	tmp[1] = buf_p[1];
	targa_header.colormap_index = LittleShort ( *((short *)tmp) );
	buf_p+=2;
	tmp[0] = buf_p[0];
	tmp[1] = buf_p[1];
	targa_header.colormap_length = LittleShort ( *((short *)tmp) );
	buf_p+=2;
	targa_header.colormap_size = *buf_p++;
	targa_header.x_origin = LittleShort ( *((short *)buf_p) );
	buf_p+=2;
	targa_header.y_origin = LittleShort ( *((short *)buf_p) );
	buf_p+=2;
	targa_header.width = LittleShort ( *((short *)buf_p) );
	buf_p+=2;
	targa_header.height = LittleShort ( *((short *)buf_p) );
	buf_p+=2;
	targa_header.pixel_size = *buf_p++;
	targa_header.attributes = *buf_p++;

	if (targa_header.image_type!=2 
		&& targa_header.image_type!=10) 
		ri.Sys_Error (ERR_DROP, "LoadTGA: Only type 2 and 10 targa RGB images supported\n");

	if (targa_header.colormap_type !=0 
		|| (targa_header.pixel_size!=32 && targa_header.pixel_size!=24))
		ri.Sys_Error (ERR_DROP, "LoadTGA: Only 32 or 24 bit images supported (no colormaps)\n");

	columns = targa_header.width;
	rows = targa_header.height;
	numPixels = columns * rows;

	if (width)
		*width = columns;
	if (height)
		*height = rows;

	targa_rgba = malloc (numPixels*4);
	*pic = targa_rgba;

	if (targa_header.id_length != 0)
		buf_p += targa_header.id_length;  // skip TARGA image comment
	
	if (targa_header.image_type==2) {  // Uncompressed, RGB images
		for(row=rows-1; row>=0; row--) {
			pixbuf = targa_rgba + row*columns*4;
			for(column=0; column<columns; column++) {
				unsigned char red,green,blue,alphabyte;
				switch (targa_header.pixel_size) {
					case 24:
							
							blue = *buf_p++;
							green = *buf_p++;
							red = *buf_p++;
							*pixbuf++ = red;
							*pixbuf++ = green;
							*pixbuf++ = blue;
							*pixbuf++ = 255;
							break;
					case 32:
							blue = *buf_p++;
							green = *buf_p++;
							red = *buf_p++;
							alphabyte = *buf_p++;
							*pixbuf++ = red;
							*pixbuf++ = green;
							*pixbuf++ = blue;
							*pixbuf++ = alphabyte;
							break;
				}
			}
		}
	}
	else if (targa_header.image_type==10) {   // Runlength encoded RGB images
		unsigned char red,green,blue,alphabyte,packetHeader,packetSize,j;
		for(row=rows-1; row>=0; row--) {
			pixbuf = targa_rgba + row*columns*4;
			for(column=0; column<columns; ) {
				packetHeader= *buf_p++;
				packetSize = 1 + (packetHeader & 0x7f);
				if (packetHeader & 0x80) {        // run-length packet
					switch (targa_header.pixel_size) {
						case 24:
								blue = *buf_p++;
								green = *buf_p++;
								red = *buf_p++;
								alphabyte = 255;
								break;
						case 32:
								blue = *buf_p++;
								green = *buf_p++;
								red = *buf_p++;
								alphabyte = *buf_p++;
								break;
					}
	
					for(j=0;j<packetSize;j++) {
						*pixbuf++=red;
						*pixbuf++=green;
						*pixbuf++=blue;
						*pixbuf++=alphabyte;
						column++;
						if (column==columns) { // run spans across rows
							column=0;
							if (row>0)
								row--;
							else
								goto breakOut;
							pixbuf = targa_rgba + row*columns*4;
						}
					}
				}
				else {                            // non run-length packet
					for(j=0;j<packetSize;j++) {
						switch (targa_header.pixel_size) {
							case 24:
									blue = *buf_p++;
									green = *buf_p++;
									red = *buf_p++;
									*pixbuf++ = red;
									*pixbuf++ = green;
									*pixbuf++ = blue;
									*pixbuf++ = 255;
									break;
							case 32:
									blue = *buf_p++;
									green = *buf_p++;
									red = *buf_p++;
									alphabyte = *buf_p++;
									*pixbuf++ = red;
									*pixbuf++ = green;
									*pixbuf++ = blue;
									*pixbuf++ = alphabyte;
									break;
						}
						column++;
						if (column==columns) { // pixel packet run spans across rows
							column=0;
							if (row>0)
								row--;
							else
								goto breakOut;
							pixbuf = targa_rgba + row*columns*4;
						}						
					}
				}
			}
			breakOut:;
		}
	}

	ri.FS_FreeFile (buffer);
}


/*
====================================================================

IMAGE FLOOD FILLING

====================================================================
*/


/*
=================
Mod_FloodFillSkin

Fill background pixels so mipmapping doesn't have haloes
=================
*/

typedef struct
{
	short		x, y;
} floodfill_t;

// must be a power of 2
#define FLOODFILL_FIFO_SIZE 0x1000
#define FLOODFILL_FIFO_MASK (FLOODFILL_FIFO_SIZE - 1)

#define FLOODFILL_STEP( off, dx, dy ) \
{ \
	if (pos[off] == fillcolor) \
	{ \
		pos[off] = 255; \
		fifo[inpt].x = x + (dx), fifo[inpt].y = y + (dy); \
		inpt = (inpt + 1) & FLOODFILL_FIFO_MASK; \
	} \
	else if (pos[off] != 255) fdc = pos[off]; \
}

void R_FloodFillSkin( byte *skin, int skinwidth, int skinheight )
{
	byte				fillcolor = *skin; // assume this is the pixel to fill
	floodfill_t			fifo[FLOODFILL_FIFO_SIZE];
	int					inpt = 0, outpt = 0;
	int					filledcolor = -1;
	int					i;

	if (filledcolor == -1)
	{
		filledcolor = 0;
		// attempt to find opaque black
		for (i = 0; i < 256; ++i)
			if (d_8to24table[i] == (255 << 0)) // alpha 1.0
			{
				filledcolor = i;
				break;
			}
	}

	// can't fill to filled color or to transparent color (used as visited marker)
	if ((fillcolor == filledcolor) || (fillcolor == 255))
	{
		//printf( "not filling skin from %d to %d\n", fillcolor, filledcolor );
		return;
	}

	fifo[inpt].x = 0, fifo[inpt].y = 0;
	inpt = (inpt + 1) & FLOODFILL_FIFO_MASK;

	while (outpt != inpt)
	{
		int			x = fifo[outpt].x, y = fifo[outpt].y;
		int			fdc = filledcolor;
		byte		*pos = &skin[x + skinwidth * y];

		outpt = (outpt + 1) & FLOODFILL_FIFO_MASK;

		if (x > 0)				FLOODFILL_STEP( -1, -1, 0 );
		if (x < skinwidth - 1)	FLOODFILL_STEP( 1, 1, 0 );
		if (y > 0)				FLOODFILL_STEP( -skinwidth, 0, -1 );
		if (y < skinheight - 1)	FLOODFILL_STEP( skinwidth, 0, 1 );
		skin[x + skinwidth * y] = fdc;
	}
}

//=======================================================


/*
================
GL_ResampleTexture
================
*/
void GL_ResampleTexture (unsigned *in, int inwidth, int inheight, unsigned *out,  int outwidth, int outheight)
{
	int		i, j;
	unsigned	*inrow, *inrow2;
	unsigned	frac, fracstep;
	unsigned	p1[1024], p2[1024];
	byte		*pix1, *pix2, *pix3, *pix4;

	fracstep = inwidth*0x10000/outwidth;

	frac = fracstep>>2;
	for (i=0 ; i<outwidth ; i++)
	{
		p1[i] = 4*(frac>>16);
		frac += fracstep;
	}
	frac = 3*(fracstep>>2);
	for (i=0 ; i<outwidth ; i++)
	{
		p2[i] = 4*(frac>>16);
		frac += fracstep;
	}

	for (i=0 ; i<outheight ; i++, out += outwidth)
	{
		inrow = in + inwidth*(int)((i+0.25)*inheight/outheight);
		inrow2 = in + inwidth*(int)((i+0.75)*inheight/outheight);
		frac = fracstep >> 1;
		for (j=0 ; j<outwidth ; j++)
		{
			pix1 = (byte *)inrow + p1[j];
			pix2 = (byte *)inrow + p2[j];
			pix3 = (byte *)inrow2 + p1[j];
			pix4 = (byte *)inrow2 + p2[j];
			((byte *)(out+j))[0] = (pix1[0] + pix2[0] + pix3[0] + pix4[0])>>2;
			((byte *)(out+j))[1] = (pix1[1] + pix2[1] + pix3[1] + pix4[1])>>2;
			((byte *)(out+j))[2] = (pix1[2] + pix2[2] + pix3[2] + pix4[2])>>2;
			((byte *)(out+j))[3] = (pix1[3] + pix2[3] + pix3[3] + pix4[3])>>2;
		}
	}
}

/*
================
GL_LightScaleTexture

Scale up the pixel values in a texture to increase the
lighting range
================
*/
void GL_LightScaleTexture (unsigned *in, int inwidth, int inheight, qboolean only_gamma )
{
	if ( only_gamma )
	{
		int		i, c;
		byte	*p;

		p = (byte *)in;

		c = inwidth*inheight;
		for (i=0 ; i<c ; i++, p+=4)
		{
			p[0] = gammatable[p[0]];
			p[1] = gammatable[p[1]];
			p[2] = gammatable[p[2]];
		}
	}
	else
	{
		int		i, c;
		byte	*p;

		p = (byte *)in;

		c = inwidth*inheight;
		for (i=0 ; i<c ; i++, p+=4)
		{
			p[0] = gammatable[intensitytable[p[0]]];
			p[1] = gammatable[intensitytable[p[1]]];
			p[2] = gammatable[intensitytable[p[2]]];
		}
	}
}

/*
================
GL_MipMap

Operates in place, quartering the size of the texture
================
*/
void GL_MipMap (byte *in, int width, int height)
{
	int		i, j;
	byte	*out;

	width <<=2;
	height >>= 1;
	out = in;
	for (i=0 ; i<height ; i++, in+=width)
	{
		for (j=0 ; j<width ; j+=8, out+=4, in+=8)
		{
			out[0] = (in[0] + in[4] + in[width+0] + in[width+4])>>2;
			out[1] = (in[1] + in[5] + in[width+1] + in[width+5])>>2;
			out[2] = (in[2] + in[6] + in[width+2] + in[width+6])>>2;
			out[3] = (in[3] + in[7] + in[width+3] + in[width+7])>>2;
		}
	}
}

/*
===============
GL_Upload32

Returns has_alpha
===============
*/
void GL_BuildPalettedTexture( unsigned char *paletted_texture, unsigned char *scaled, int scaled_width, int scaled_height )
{
	int i;

	for ( i = 0; i < scaled_width * scaled_height; i++ )
	{
		unsigned int r, g, b, c;

		r = ( scaled[0] >> 3 ) & 31;
		g = ( scaled[1] >> 2 ) & 63;
		b = ( scaled[2] >> 3 ) & 31;

		c = r | ( g << 5 ) | ( b << 11 );

		paletted_texture[i] = gl_state.d_16to8table[c];

		scaled += 4;
	}
}

int		upload_width, upload_height;
qboolean uploaded_paletted;

qboolean GL_Upload32 (unsigned *data, int width, int height,  qboolean mipmap)
{
	int			samples;
	unsigned	scaled[256*256];
	unsigned char paletted_texture[256*256];
	int			scaled_width, scaled_height;
	int			i, c;
	byte		*scan;
	int comp;

	uploaded_paletted = false;

	for (scaled_width = 1 ; scaled_width < width ; scaled_width<<=1)
		;
	if (gl_round_down->value && scaled_width > width && mipmap)
		scaled_width >>= 1;
	for (scaled_height = 1 ; scaled_height < height ; scaled_height<<=1)
		;
	if (gl_round_down->value && scaled_height > height && mipmap)
		scaled_height >>= 1;

	// let people sample down the world textures for speed
	if (mipmap)
	{
		scaled_width >>= (int)gl_picmip->value;
		scaled_height >>= (int)gl_picmip->value;
	}

	// don't ever bother with >256 textures
	if (scaled_width > 256)
		scaled_width = 256;
	if (scaled_height > 256)
		scaled_height = 256;

	if (scaled_width < 1)
		scaled_width = 1;
	if (scaled_height < 1)
		scaled_height = 1;

	upload_width = scaled_width;
	upload_height = scaled_height;

	if (scaled_width * scaled_height > sizeof(scaled)/4)
		ri.Sys_Error (ERR_DROP, "GL_Upload32: too big");

	// scan the texture for any non-255 alpha
	c = width*height;
	scan = ((byte *)data) + 3;
	samples = gl_solid_format;
	for (i=0 ; i<c ; i++, scan += 4)
	{
		if ( *scan != 255 )
		{
			samples = gl_alpha_format;
			break;
		}
	}

	if (samples == gl_solid_format)
	    comp = gl_tex_solid_format;
	else if (samples == gl_alpha_format)
	    comp = gl_tex_alpha_format;
	else {
	    ri.Con_Printf (PRINT_ALL,
			   "Unknown number of texture components %i\n",
			   samples);
	    comp = samples;
	}

#if 0
	if (mipmap)
		gluBuild2DMipmaps (GL_TEXTURE_2D, samples, width, height, GL_RGBA, GL_UNSIGNED_BYTE, trans);
	else if (scaled_width == width && scaled_height == height)
		qglTexImage2D (GL_TEXTURE_2D, 0, comp, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, trans);
	else
	{
		gluScaleImage (GL_RGBA, width, height, GL_UNSIGNED_BYTE, trans,
			scaled_width, scaled_height, GL_UNSIGNED_BYTE, scaled);
		qglTexImage2D (GL_TEXTURE_2D, 0, comp, scaled_width, scaled_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, scaled);
	}
#else

	if (scaled_width == width && scaled_height == height)
	{
		if (!mipmap)
		{
			if ( qglColorTableEXT && gl_ext_palettedtexture->value && samples == gl_solid_format )
			{
				uploaded_paletted = true;
				GL_BuildPalettedTexture( paletted_texture, ( unsigned char * ) data, scaled_width, scaled_height );