1
0
Fork 0
flightgear/utils/Modeller/texture.cxx
2010-10-08 23:48:01 +02:00

969 lines
23 KiB
C++

/*
* Texture manipulation routines
*
* Copyright (c) Mark J. Kilgard, 1997.
* Code added in april 2003 by Erik Hofman
*
* This program is freely distributable without licensing fees
* and is provided without guarantee or warrantee expressed or
* implied. This program is -not- in the public domain.
*
* $Id$
*/
#include <simgear/compiler.h>
#ifdef WIN32
# include <windows.h>
#endif
#include <osg/Matrixf>
#include <math.h>
#include <zlib.h>
#include "texture.hxx"
#include "colours.h"
const char *FILE_OPEN_ERROR = "Unable to open file.";
const char *WRONG_COUNT = "Unsupported number of color channels.";
const char *NO_TEXTURE = "No texture data resident.";
const char *OUT_OF_MEMORY = "Out of memory.";
SGTexture::SGTexture()
: texture_id(0),
texture_data(0),
num_colors(3),
file(0)
{
}
SGTexture::SGTexture(unsigned int width, unsigned int height)
: texture_id(0),
errstr("")
{
texture_data = new GLubyte[ width * height * 3 ];
}
SGTexture::~SGTexture()
{
delete[] texture_data;
if ( texture_id != 0 ) {
free_id();
}
}
void
SGTexture::bind()
{
bool gen = false;
if (!texture_id) {
#ifdef GL_VERSION_1_1
glGenTextures(1, &texture_id);
#elif GL_EXT_texture_object
glGenTexturesEXT(1, &texture_id);
#endif
gen = true;
}
#ifdef GL_VERSION_1_1
glBindTexture(GL_TEXTURE_2D, texture_id);
#elif GL_EXT_texture_object
glBindTextureEXT(GL_TEXTURE_2D, texture_id);
#endif
if (gen) {
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
}
}
/**
* A function to resize the OpenGL window which will be used by
* the dynamic texture generating routines.
*
* @param width The width of the new window
* @param height The height of the new window
*/
void
SGTexture::resize(unsigned int width, unsigned int height)
{
using namespace osg;
GLfloat aspect;
// Make sure that we don't get a divide by zero exception
if (height == 0)
height = 1;
// Set the viewport for the OpenGL window
glViewport(0, 0, width, height);
// Calculate the aspect ratio of the window
aspect = width/height;
// Go to the projection matrix, this gets modified by the perspective
// calulations
glMatrixMode(GL_PROJECTION);
// Do the perspective calculations
Matrixf proj = Matrixf::perspective(45.0, aspect, 1.0, 400.0);
glLoadMatrix(proj.ptr());
// Return to the modelview matrix
glMatrixMode(GL_MODELVIEW);
}
/**
* A function to prepare the OpenGL state machine for dynamic
* texture generation.
*
* @param width The width of the texture
* @param height The height of the texture
*/
void
SGTexture::prepare(unsigned int width, unsigned int height) {
texture_width = width;
texture_height = height;
// Resize the OpenGL window to the size of our dynamic texture
resize(texture_width, texture_height);
glClearColor(0.0, 0.0, 0.0, 1.0);
}
/**
* A function to generate the dynamic texture.
*
* The actual texture can be accessed by calling get_texture()
*
* @param width The width of the previous OpenGL window
* @param height The height of the previous OpenGL window
*/
void
SGTexture::finish(unsigned int width, unsigned int height) {
// If a texture hasn't been created then it gets created, and the contents
// of the frame buffer gets copied into it. If the texture has already been
// created then its contents just get updated.
bind();
if (!texture_data)
{
// Copies the contents of the frame buffer into the texture
glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 0, 0,
texture_width, texture_height, 0);
} else {
// Copies the contents of the frame buffer into the texture
glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0,
texture_width, texture_height);
}
// Set the OpenGL window back to its previous size
resize(width, height);
// Clear the window back to black
glClearColor(0.0, 0.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}
void
SGTexture::read_alpha_texture(const char *name)
{
GLubyte *lptr;
SGTexture::ImageRec *image;
int y;
delete[] texture_data;
image = ImageOpen(name);
if(!image) {
errstr = FILE_OPEN_ERROR;
return;
}
texture_width = image->xsize;
texture_height = image->ysize;
// printf("image->zsize = %d\n", image->zsize);
if (image->zsize != 1) {
ImageClose(image);
errstr = WRONG_COUNT;
return;
}
texture_data = new GLubyte[ image->xsize * image->ysize ];
num_colors = 1;
if (!texture_data) {
errstr = NO_TEXTURE;
return;
}
lptr = texture_data;
for(y=0; y<image->ysize; y++) {
ImageGetRow(image,lptr,y,0);
lptr += image->xsize;
}
ImageClose(image);
}
void
SGTexture::read_rgb_texture(const char *name)
{
GLubyte *ptr;
GLubyte *rbuf, *gbuf, *bbuf;
SGTexture::ImageRec *image;
int y;
delete[] texture_data;
image = ImageOpen(name);
if(!image) {
errstr = FILE_OPEN_ERROR;
return;
}
texture_width = image->xsize;
texture_height = image->ysize;
if (image->zsize < 1 || image->zsize > 4) {
ImageClose(image);
errstr = WRONG_COUNT;
return;
}
num_colors = 3;
texture_data = new GLubyte[ image->xsize * image->ysize * num_colors ];
rbuf = new GLubyte[ image->xsize ];
gbuf = new GLubyte[ image->xsize ];
bbuf = new GLubyte[ image->xsize ];
if(!texture_data || !rbuf || !gbuf || !bbuf) {
delete[] texture_data;
delete[] rbuf;
delete[] gbuf;
delete[] bbuf;
errstr = OUT_OF_MEMORY;
return;
}
ptr = texture_data;
for(y=0; y<image->ysize; y++) {
if(image->zsize == 4 || image->zsize == 3) {
ImageGetRow(image,rbuf,y,0);
ImageGetRow(image,gbuf,y,1);
ImageGetRow(image,bbuf,y,2);
} else {
ImageGetRow(image,rbuf,y,0);
memcpy(gbuf,rbuf,image->xsize);
memcpy(bbuf,rbuf,image->xsize);
}
rgbtorgb(rbuf,gbuf,bbuf,ptr,image->xsize);
ptr += (image->xsize * num_colors);
}
ImageClose(image);
delete[] rbuf;
delete[] gbuf;
delete[] bbuf;
}
void
SGTexture::read_rgba_texture(const char *name)
{
GLubyte *ptr;
GLubyte *rbuf, *gbuf, *bbuf, *abuf;
SGTexture::ImageRec *image;
int y;
delete[] texture_data;
image = ImageOpen(name);
if(!image) {
errstr = FILE_OPEN_ERROR;
return;
}
texture_width = image->xsize;
texture_height = image->ysize;
if (image->zsize < 1 || image->zsize > 4) {
ImageClose(image);
errstr = WRONG_COUNT;
return;
}
num_colors = 4;
texture_data = new GLubyte[ image->xsize * image->ysize * num_colors ];
rbuf = new GLubyte[ image->xsize ];
gbuf = new GLubyte[ image->xsize ];
bbuf = new GLubyte[ image->xsize ];
abuf = new GLubyte[ image->xsize ];
if(!texture_data || !rbuf || !gbuf || !bbuf || !abuf) {
delete[] texture_data;
delete[] rbuf;
delete[] gbuf;
delete[] bbuf;
delete[] abuf;
errstr = OUT_OF_MEMORY;
return;
}
ptr = texture_data;
for(y=0; y<image->ysize; y++) {
if(image->zsize == 4) {
ImageGetRow(image,rbuf,y,0);
ImageGetRow(image,gbuf,y,1);
ImageGetRow(image,bbuf,y,2);
ImageGetRow(image,abuf,y,3);
} else if(image->zsize == 3) {
ImageGetRow(image,rbuf,y,0);
ImageGetRow(image,gbuf,y,1);
ImageGetRow(image,bbuf,y,2);
memset(abuf, 255, image->xsize);
} else if(image->zsize == 2) {
ImageGetRow(image,rbuf,y,0);
memcpy(gbuf,rbuf,image->xsize);
memcpy(bbuf,rbuf,image->xsize);
ImageGetRow(image,abuf,y,1);
} else {
ImageGetRow(image,rbuf,y,0);
memcpy(gbuf,rbuf,image->xsize);
memcpy(bbuf,rbuf,image->xsize);
memset(abuf, 255, image->xsize);
}
rgbatorgba(rbuf,gbuf,bbuf,abuf,ptr,image->xsize);
ptr += (image->xsize * num_colors);
}
ImageClose(image);
delete[] rbuf;
delete[] gbuf;
delete[] bbuf;
delete[] abuf;
}
void
SGTexture::read_raw_texture(const char *name)
{
GLubyte *ptr;
SGTexture::ImageRec *image;
int y;
delete[] texture_data;
image = RawImageOpen(name);
if(!image) {
errstr = FILE_OPEN_ERROR;
return;
}
texture_width = 256;
texture_height = 256;
texture_data = new GLubyte[ 256 * 256 * 3 ];
if(!texture_data) {
errstr = OUT_OF_MEMORY;
return;
}
ptr = texture_data;
for(y=0; y<256; y++) {
gzread(image->file, ptr, 256*3);
ptr+=256*3;
}
ImageClose(image);
}
void
SGTexture::read_r8_texture(const char *name)
{
unsigned char c[1];
GLubyte *ptr;
SGTexture::ImageRec *image;
int xy;
delete[] texture_data;
//it wouldn't make sense to write a new function ...
image = RawImageOpen(name);
if(!image) {
errstr = FILE_OPEN_ERROR;
return;
}
texture_width = 256;
texture_height = 256;
texture_data = new GLubyte [ 256 * 256 * 3 ];
if(!texture_data) {
errstr = OUT_OF_MEMORY;
return;
}
ptr = texture_data;
for(xy=0; xy<(256*256); xy++) {
gzread(image->file, c, 1);
//look in the table for the right colours
ptr[0]=msfs_colour[c[0]][0];
ptr[1]=msfs_colour[c[0]][1];
ptr[2]=msfs_colour[c[0]][2];
ptr+=3;
}
ImageClose(image);
}
void
SGTexture::write_texture(const char *name) {
SGTexture::ImageRec *image = ImageWriteOpen(name);
for (int c=0; c<num_colors; c++) {
GLubyte *ptr = texture_data + c;
for (int y=0; y<texture_height; y++) {
for (int x=0; x<texture_width; x++) {
image->tmp[x]=*ptr;
ptr = ptr + num_colors;
}
fwrite(image->tmp, 1, texture_width, file);
}
}
ImageClose(image);
}
void
SGTexture::set_pixel(GLuint x, GLuint y, GLubyte *c)
{
if (!texture_data) {
errstr = NO_TEXTURE;
return;
}
unsigned int pos = (x + y*texture_width) * num_colors;
memcpy(texture_data+pos, c, num_colors);
}
GLubyte *
SGTexture::get_pixel(GLuint x, GLuint y)
{
static GLubyte c[4] = {0, 0, 0, 0};
if (!texture_data) {
errstr = NO_TEXTURE;
return c;
}
unsigned int pos = (x + y*texture_width)*num_colors;
memcpy(c, texture_data + pos, num_colors);
return c;
}
SGTexture::ImageRec *
SGTexture::ImageOpen(const char *fileName)
{
union {
int testWord;
char testByte[4];
} endianTest;
SGTexture::ImageRec *image;
int swapFlag;
int x;
endianTest.testWord = 1;
if (endianTest.testByte[0] == 1) {
swapFlag = 1;
} else {
swapFlag = 0;
}
image = new SGTexture::ImageRec;
memset(image, 0, sizeof(SGTexture::ImageRec));
if (image == 0) {
errstr = OUT_OF_MEMORY;
return 0;
}
if ((image->file = gzopen(fileName, "rb")) == 0) {
errstr = FILE_OPEN_ERROR;
return 0;
}
gzread(image->file, image, 12);
if (swapFlag) {
ConvertShort(&image->imagic, 6);
}
image->tmp = new GLubyte[ image->xsize * 256 ];
if (image->tmp == 0) {
errstr = OUT_OF_MEMORY;
return 0;
}
if ((image->type & 0xFF00) == 0x0100) {
x = image->ysize * image->zsize * (int) sizeof(unsigned);
image->rowStart = new unsigned[x];
image->rowSize = new int[x];
if (image->rowStart == 0 || image->rowSize == 0) {
errstr = OUT_OF_MEMORY;
return 0;
}
image->rleEnd = 512 + (2 * x);
gzseek(image->file, 512, SEEK_SET);
gzread(image->file, image->rowStart, x);
gzread(image->file, image->rowSize, x);
if (swapFlag) {
ConvertUint(image->rowStart, x/(int) sizeof(unsigned));
ConvertUint((unsigned *)image->rowSize, x/(int) sizeof(int));
}
}
return image;
}
void
SGTexture::ImageClose(SGTexture::ImageRec *image) {
if (image->file) gzclose(image->file);
if (file) fclose(file);
delete[] image->tmp;
delete[] image->rowStart;
delete[] image->rowSize;
delete image;
}
SGTexture::ImageRec *
SGTexture::RawImageOpen(const char *fileName)
{
union {
int testWord;
char testByte[4];
} endianTest;
SGTexture::ImageRec *image;
int swapFlag;
endianTest.testWord = 1;
if (endianTest.testByte[0] == 1) {
swapFlag = 1;
} else {
swapFlag = 0;
}
image = new SGTexture::ImageRec;
memset(image, 0, sizeof(SGTexture::ImageRec));
if (image == 0) {
errstr = OUT_OF_MEMORY;
return 0;
}
if ((image->file = gzopen(fileName, "rb")) == 0) {
errstr = FILE_OPEN_ERROR;
return 0;
}
gzread(image->file, image, 12);
if (swapFlag) {
ConvertShort(&image->imagic, 6);
}
//just allocate a pseudo value as I'm too lazy to change ImageClose()...
image->tmp = new GLubyte[1];
if (image->tmp == 0) {
errstr = OUT_OF_MEMORY;
return 0;
}
return image;
}
SGTexture::ImageRec *
SGTexture::ImageWriteOpen(const char *fileName)
{
union {
int testWord;
char testByte[4];
} endianTest;
ImageRec* image;
int swapFlag;
int x;
endianTest.testWord = 1;
if (endianTest.testByte[0] == 1) {
swapFlag = 1;
} else {
swapFlag = 0;
}
image = new SGTexture::ImageRec;
memset(image, 0, sizeof(SGTexture::ImageRec));
if (image == 0) {
errstr = OUT_OF_MEMORY;
return 0;
}
if ((file = fopen(fileName, "wb")) == 0) {
errstr = FILE_OPEN_ERROR;
return 0;
}
image->imagic = 474;
image->type = 0x0001;
image->dim = (num_colors > 1) ? 3 : 2;
image->xsize = texture_width;
image->ysize = texture_height;
image->zsize = num_colors;
if (swapFlag) {
ConvertShort(&image->imagic, 6);
}
fwrite(image, 1, 12, file);
fseek(file, 512, SEEK_SET);
image->tmp = new GLubyte[ image->xsize * 256 ];
if (image->tmp == 0) {
errstr = OUT_OF_MEMORY;
return 0;
}
if ((image->type & 0xFF00) == 0x0100) {
x = image->ysize * image->zsize * (int) sizeof(unsigned);
image->rowStart = new unsigned[x];
image->rowSize = new int[x];
if (image->rowStart == 0 || image->rowSize == 0) {
errstr = OUT_OF_MEMORY;
return 0;
}
image->rleEnd = 512 + (2 * x);
fseek(file, 512, SEEK_SET);
fread(image->rowStart, 1, x, file);
fread(image->rowSize, 1, x, file);
if (swapFlag) {
ConvertUint(image->rowStart, x/(int) sizeof(unsigned));
ConvertUint((unsigned *)image->rowSize, x/(int) sizeof(int));
}
}
return image;
}
void
SGTexture::ImageGetRow(SGTexture::ImageRec *image, GLubyte *buf, int y, int z) {
GLubyte *iPtr, *oPtr, pixel;
int count;
if ((image->type & 0xFF00) == 0x0100) {
gzseek(image->file, (long) image->rowStart[y+z*image->ysize], SEEK_SET);
int size = image->rowSize[y+z*image->ysize];
gzread(image->file, image->tmp, size);
iPtr = image->tmp;
oPtr = buf;
for (GLubyte *limit = iPtr + size; iPtr < limit;) {
pixel = *iPtr++;
count = (int)(pixel & 0x7F);
if (!count) {
errstr = WRONG_COUNT;
return;
}
if (pixel & 0x80) {
while (iPtr < limit && count--) {
*oPtr++ = *iPtr++;
}
} else if (iPtr < limit) {
pixel = *iPtr++;
while (count--) {
*oPtr++ = pixel;
}
}
}
} else {
gzseek(image->file, 512+(y*image->xsize)+(z*image->xsize*image->ysize),
SEEK_SET);
gzread(image->file, buf, image->xsize);
}
}
void
SGTexture::ImagePutRow(SGTexture::ImageRec *image, GLubyte *buf, int y, int z) {
GLubyte *iPtr, *oPtr, pixel;
int count;
if ((image->type & 0xFF00) == 0x0100) {
fseek(file, (long) image->rowStart[y+z*image->ysize], SEEK_SET);
fread( image->tmp, 1, (unsigned int)image->rowSize[y+z*image->ysize],
file);
iPtr = image->tmp;
oPtr = buf;
for (;;) {
pixel = *iPtr++;
count = (int)(pixel & 0x7F);
if (!count) {
errstr = WRONG_COUNT;
return;
}
if (pixel & 0x80) {
while (count--) {
*oPtr++ = *iPtr++;
}
} else {
pixel = *iPtr++;
while (count--) {
*oPtr++ = pixel;
}
}
}
} else {
fseek(file, 512+(y*image->xsize)+(z*image->xsize*image->ysize),
SEEK_SET);
fread(buf, 1, image->xsize, file);
}
}
void
SGTexture::rgbtorgb(GLubyte *r, GLubyte *g, GLubyte *b, GLubyte *l, int n) {
while(n--) {
l[0] = r[0];
l[1] = g[0];
l[2] = b[0];
l += 3; r++; g++; b++;
}
}
void
SGTexture::rgbatorgba(GLubyte *r, GLubyte *g, GLubyte *b, GLubyte *a,
GLubyte *l, int n) {
while(n--) {
l[0] = r[0];
l[1] = g[0];
l[2] = b[0];
l[3] = a[0];
l += 4; r++; g++; b++; a++;
}
}
void
SGTexture::ConvertShort(unsigned short *array, unsigned int length) {
unsigned short b1, b2;
unsigned char *ptr;
ptr = (unsigned char *)array;
while (length--) {
b1 = *ptr++;
b2 = *ptr++;
*array++ = (b1 << 8) | (b2);
}
}
void
SGTexture::ConvertUint(unsigned *array, unsigned int length) {
unsigned int b1, b2, b3, b4;
unsigned char *ptr;
ptr = (unsigned char *)array;
while (length--) {
b1 = *ptr++;
b2 = *ptr++;
b3 = *ptr++;
b4 = *ptr++;
*array++ = (b1 << 24) | (b2 << 16) | (b3 << 8) | (b4);
}
}
void
SGTexture::make_monochrome(float contrast, GLubyte r, GLubyte g, GLubyte b) {
if (num_colors >= 3)
return;
GLubyte ap[3];
for (int y=0; y<texture_height; y++)
for (int x=0; x<texture_width; x++)
{
GLubyte *rgb = get_pixel(x,y);
GLubyte avg = (rgb[0] + rgb[1] + rgb[2]) / 3;
if (contrast != 1.0) {
float pixcol = -1.0 + (avg/128);
avg = 128 + int(128*pow(pixcol, contrast));
}
ap[0] = avg*r/255;
ap[1] = avg*g/255;
ap[2] = avg*b/255;
set_pixel(x,y,ap);
}
}
void
SGTexture::make_grayscale(float contrast) {
if (num_colors < 3)
return;
int colors = (num_colors == 3) ? 1 : 2;
GLubyte *map = new GLubyte[ texture_width * texture_height * colors ];
for (int y=0; y<texture_height; y++)
for (int x=0; x<texture_width; x++)
{
GLubyte *rgb = get_pixel(x,y);
GLubyte avg = (rgb[0] + rgb[1] + rgb[2]) / 3;
if (contrast != 1.0) {
float pixcol = -1.0 + (avg/128);
avg = 128 + int(128*pow(pixcol, contrast));
}
int pos = (x + y*texture_width)*colors;
map[pos] = avg;
if (colors > 1)
map[pos+1] = rgb[3];
}
delete[] texture_data;
texture_data = map;
num_colors = colors;
}
void
SGTexture::make_maxcolorwindow() {
GLubyte minmaxc[2] = {255, 0};
int pos = 0;
int max = num_colors;
if (num_colors == 2) max = 1;
if (num_colors == 4) max = 3;
while (pos < texture_width * texture_height * num_colors) {
for (int i=0; i < max; i++) {
GLubyte c = texture_data[pos+i];
if (c < minmaxc[0]) minmaxc[0] = c;
if (c > minmaxc[1]) minmaxc[1] = c;
}
pos += num_colors;
}
GLubyte offs = minmaxc[0];
float factor = 255.0 / float(minmaxc[1] - minmaxc[0]);
// printf("Min: %i, Max: %i, Factor: %f\n", offs, minmaxc[1], factor);
pos = 0;
while (pos < texture_width * texture_height * num_colors) {
for (int i=0; i < max; i++) {
texture_data[pos+i] -= offs;
texture_data[pos+i] = int(factor * texture_data[pos+i]);
}
pos += num_colors;
}
}
void
SGTexture::make_normalmap(float brightness, float contrast) {
make_grayscale(contrast);
make_maxcolorwindow();
int colors = (num_colors == 1) ? 3 : 4;
bool alpha = (colors > 3);
int tsize = texture_width * texture_height * colors;
GLubyte *map = new GLubyte[ tsize ];
int mpos = 0, dpos = 0;
for (int y=0; y<texture_height; y++) {
int ytw = y*texture_width;
for (int x=0; x<texture_width; x++)
{
int xp1 = (x < (texture_width-1)) ? x+1 : 0;
int yp1 = (y < (texture_height-1)) ? y+1 : 0;
int posxp1 = (xp1 + ytw)*num_colors;
int posyp1 = (x + yp1*texture_width)*num_colors;
float fx,fy;
GLubyte c = texture_data[dpos];
GLubyte cx1 = texture_data[posxp1];
GLubyte cy1 = texture_data[posyp1];
if (alpha) {
GLubyte a = texture_data[dpos+1];
GLubyte ax1 = texture_data[posxp1+1];
GLubyte ay1 = texture_data[posyp1+1];
c = (c + a)/2;
cx1 = (cx1 + ax1)/2;
cy1 = (cy1 + ay1)/2;
map[mpos+3] = a;
}
fx = asin((c/256.0-cx1/256.0))/1.57079633;
fy = asin((cy1/256.0-c/256.0))/1.57079633;
map[mpos+0] = (GLuint)(fx*256.0)-128;
map[mpos+1] = (GLuint)(fy*256.0)-128;
map[mpos+2] = 127+int(brightness*128); // 255-c/2;
mpos += colors;
dpos += num_colors;
}
}
delete[] texture_data;
texture_data = map;
num_colors = colors;
}
void
SGTexture::make_bumpmap(float brightness, float contrast) {
make_grayscale(contrast);
int colors = (num_colors == 1) ? 1 : 2;
GLubyte *map = new GLubyte[ texture_width * texture_height * colors ];
for (int y=0; y<texture_height; y++)
for (int x=0; x<texture_width; x++)
{
int mpos = (x + y*texture_width)*colors;
int dpos = (x + y*texture_width)*num_colors;
int xp1 = (x < (texture_width-1)) ? x+1 : 0;
int yp1 = (y < (texture_height-1)) ? y+1 : 0;
int posxp1 = (xp1 + y*texture_width)*num_colors;
int posyp1 = (x + yp1*texture_width)*num_colors;
map[mpos] = (127 - ((texture_data[dpos]-texture_data[posxp1]) -
((texture_data[dpos]-texture_data[posyp1]))/4))/2;
if (colors > 1)
map[mpos+1] = texture_data[dpos+1];
}
delete[] texture_data;
texture_data = map;
num_colors = colors;
}