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  Read an image bitmap (.bmp) file and draw it as texture
Sun Mar 20, 2011 10:12 pm 

TextureBMP.cpp
Code:
/*
* TextureBMP.cpp
*
* Loosely based on the example checker.c
* (Example 9-1, OpenGL Programming Guide, 3rd edition)
*
* Read an image from a bitmap (.bmp) file, and draw it as a texture
* map on a quad.  A cpp class RgbImage is used to read a texture
* map from a bitmap (.bmp) file.
*
* Author: Samuel R. Buss
*
* Software accompanying the book.
*      3D Computer Graphics: A Mathematical Introduction with OpenGL,
*      by S. Buss, Cambridge University Press, 2003.
*
* Software is "as-is" and carries no warranty.  It may be used without
*   restriction, but if you modify it, please change the filenames to
*   prevent confusion between different versions.
* Bug reports: Sam Buss, sbuss@ucsd.edu.
* Web page: http://math.ucsd.edu/~sbuss/MathCG
*
*/

#include <stdlib.h>
#include <GL/glut.h>
#include "RgbImage.h"

/*
* Read a texture map from a BMP bitmap file.
*/
void loadTextureFromFile(char *filename)
{   
   glClearColor (0.0, 0.0, 0.0, 0.0);
   glShadeModel(GL_FLAT);
   glEnable(GL_DEPTH_TEST);

   RgbImage theTexMap( filename );

   // Pixel alignment: each row is word aligned (aligned to a 4 byte boundary)
   //    Therefore, no need to call glPixelStore( GL_UNPACK_ALIGNMENT, ... );

   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

   gluBuild2DMipmaps(GL_TEXTURE_2D, 3,theTexMap.GetNumCols(), theTexMap.GetNumRows(),
                GL_RGB, GL_UNSIGNED_BYTE, theTexMap.ImageData() );

}

/*
* Draw the texture in the OpenGL graphics window
*/
void drawScene(void)
{
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
   glEnable(GL_TEXTURE_2D);
   glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);

   glBegin(GL_QUADS);
   
   glTexCoord2f(0.0, 0.0);
   glVertex3f(-1.0, -1.0, 0.0);
   
   glTexCoord2f(0.0, 1.0);
   glVertex3f(-1.0, 1.0, 0.0);
   
   glTexCoord2f(1.0, 1.0);
   glVertex3f(1.0, 1.0, 0.0);
   
   glTexCoord2f(1.0, 0.0);
   glVertex3f(1.0, -1.0, 0.0);
   
   glEnd();

   glFlush();
   glDisable(GL_TEXTURE_2D);
}

void resizeWindow(int w, int h)
{
   float viewWidth = 1.1;
   float viewHeight = 1.1;
   glViewport(0, 0, w, h);
   h = (h==0) ? 1 : h;
   w = (w==0) ? 1 : w;
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   if ( h < w ) {
      viewWidth *= (float)w/(float)h;
   }
   else {
      viewHeight *= (float)h/(float)w;
   }
   glOrtho( -viewWidth, viewWidth, -viewHeight, viewHeight, -1.0, 1.0 );

   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
}

void keyboard (unsigned char key, int x, int y)
{
   switch (key) {
      case 27:
         exit(0);
         break;
      default:
         break;
   }
}

char* filename = "RedLeavesTexture.bmp";

int main(int argc, char** argv)
{
   glutInit(&argc, aargv);
   glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
   glutInitWindowSize(240, 240);
   glutInitWindowPosition(100, 100);
   glutCreateWindow(argv[0]);

   loadTextureFromFile( filename );
   
   glutDisplayFunc(drawScene);
   glutReshapeFunc(resizeWindow);
   glutKeyboardFunc(keyboard);
   glutMainLoop();
   return 0;
}



RgbImage.cpp :
Code:
/*
*
* RayTrace Software Package, release 1.0.4,  February 2004.
*
* Author: Samuel R. Buss
*
* Software accompanying the book
*      3D Computer Graphics: A Mathematical Introduction with OpenGL,
*      by S. Buss, Cambridge University Press, 2003.
*
* Software is "as-is" and carries no warranty.  It may be used without
*   restriction, but if you modify it, please change the filenames to
*   prevent confusion between different versions.  Please acknowledge
*   all use of the software in any publications or products based on it.
*
* Bug reports: Sam Buss, sbuss@ucsd.edu.
* Web page: http://math.ucsd.edu/~sbuss/MathCG
*
*/

#include "RgbImage.h"

#ifndef RGBIMAGE_DONT_USE_OPENGL
#include <windows.h>
#include "GL/gl.h"
#endif

RgbImage::RgbImage( int numRows, int numCols )
{
   NumRows = numRows;
   NumCols = numCols;
   ImagePtr = new unsigned char[NumRows*GetNumBytesPerRow()];
   if ( !ImagePtr ) {
      fprintf(stderr, "Unable to allocate memory for %ld x %ld bitmap.\n",
            NumRows, NumCols);
      Reset();
      ErrorCode = MemoryError;
   }
   // Zero out the image
   unsigned char* c = ImagePtr;
   int rowLen = GetNumBytesPerRow();
   for ( int i=0; i<NumRows; i++ ) {
      for ( int j=0; j<rowLen; j++ ) {
         *(c++) = 0;
      }
   }
}

/* ********************************************************************
*  LoadBmpFile
*  Read into memory an RGB image from an uncompressed BMP file.
*  Return true for success, false for failure.  Error code is available
*     with a separate call.
*  Author: Sam Buss December 2001.
**********************************************************************/

bool RgbImage::LoadBmpFile( const char* filename )

   Reset();
   FILE* infile = fopen( filename, "rb" );      // Open for reading binary data
   if ( !infile ) {
      fprintf(stderr, "Unable to open file: %s\n", filename);
      ErrorCode = OpenError;
      return false;
   }

   bool fileFormatOK = false;
   int bChar = fgetc( infile );
   int mChar = fgetc( infile );
   if ( bChar=='B' && mChar=='M' ) {         // If starts with "BM" for "BitMap"
      skipChars( infile, 4+2+2+4+4 );         // Skip 4 fields we don't care about
      NumCols = readLong( infile );
      NumRows = readLong( infile );
      skipChars( infile, 2 );               // Skip one field
      int bitsPerPixel = readShort( infile );
      skipChars( infile, 4+4+4+4+4+4 );      // Skip 6 more fields

      if ( NumCols>0 && NumCols<=100000 && NumRows>0 && NumRows<=100000 
         && bitsPerPixel==24 && !feof(infile) ) {
         fileFormatOK = true;
      }
   }
   if ( !fileFormatOK ) {
      Reset();
      ErrorCode = FileFormatError;
      fprintf(stderr, "Not a valid 24-bit bitmap file: %s.\n", filename);
      fclose ( infile );
      return false;
   }

   // Allocate memory
   ImagePtr = new unsigned char[NumRows*GetNumBytesPerRow()];
   if ( !ImagePtr ) {
      fprintf(stderr, "Unable to allocate memory for %ld x %ld bitmap: %s.\n",
            NumRows, NumCols, filename);
      Reset();
      ErrorCode = MemoryError;
      fclose ( infile );
      return false;
   }

   unsigned char* cPtr = ImagePtr;
   for ( int i=0; i<NumRows; i++ ) {
      int j;
      for ( j=0; j<NumCols; j++ ) {
         *(cPtr+2) = fgetc( infile );   // Blue color value
         *(cPtr+1) = fgetc( infile );   // Green color value
         *cPtr = fgetc( infile );      // Red color value
         cPtr += 3;
      }
      int k=3*NumCols;               // Num bytes already read
      for ( ; k<GetNumBytesPerRow(); k++ ) {
         fgetc( infile );            // Read and ignore padding;
         *(cPtr++) = 0;
      }
   }
   if ( feof( infile ) ) {
      fprintf( stderr, "Premature end of file: %s.\n", filename );
      Reset();
      ErrorCode = ReadError;
      fclose ( infile );
      return false;
   }
   fclose( infile );   // Close the file
   return true;
}

short RgbImage::readShort( FILE* infile )
{
   // read a 16 bit integer
   unsigned char lowByte, hiByte;
   lowByte = fgetc(infile);         // Read the low order byte (little endian form)
   hiByte = fgetc(infile);         // Read the high order byte

   // Pack together
   short ret = hiByte;
   ret <<= 8;
   ret |= lowByte;
   return ret;
}

long RgbImage::readLong( FILE* infile )

   // Read in 32 bit integer
   unsigned char byte0, byte1, byte2, byte3;
   byte0 = fgetc(infile);         // Read bytes, low order to high order
   byte1 = fgetc(infile);
   byte2 = fgetc(infile);
   byte3 = fgetc(infile);

   // Pack together
   long ret = byte3;
   ret <<= 8;
   ret |= byte2;
   ret <<= 8;
   ret |= byte1;
   ret <<= 8;
   ret |= byte0;
   return ret;
}

void RgbImage::skipChars( FILE* infile, int numChars )
{
   for ( int i=0; i<numChars; i++ ) {
      fgetc( infile );
   }
}

/* ********************************************************************
*  WriteBmpFile
*  Write an RGB image to an uncompressed BMP file.
*  Return true for success, false for failure.  Error code is available
*     with a separate call.
*  Author: Sam Buss, January 2003.
**********************************************************************/

bool RgbImage::WriteBmpFile( const char* filename )
{
   FILE* outfile = fopen( filename, "wb" );      // Open for reading binary data
   if ( !outfile ) {
      fprintf(stderr, "Unable to open file: %s\n", filename);
      ErrorCode = OpenError;
      return false;
   }

   fputc('B',outfile);
   fputc('M',outfile);
   int rowLen = GetNumBytesPerRow();
   writeLong( 40+14+NumRows*rowLen, outfile );   // Length of file
   writeShort( 0, outfile );               // Reserved for future use
   writeShort( 0, outfile );
   writeLong( 40+14, outfile );            // Offset to pixel data
   writeLong( 40, outfile );               // header length
   writeLong( NumCols, outfile );            // width in pixels
   writeLong( NumRows, outfile );            // height in pixels (pos for bottom up)
   writeShort( 1, outfile );      // number of planes
   writeShort( 24, outfile );      // bits per pixel
   writeLong( 0, outfile );      // no compression
   writeLong( 0, outfile );      // not used if no compression
   writeLong( 0, outfile );      // Pixels per meter
   writeLong( 0, outfile );      // Pixels per meter
   writeLong( 0, outfile );      // unused for 24 bits/pixel
   writeLong( 0, outfile );      // unused for 24 bits/pixel

   // Now write out the pixel data:
   unsigned char* cPtr = ImagePtr;
   for ( int i=0; i<NumRows; i++ ) {
      // Write out i-th row's data
      int j;
      for ( j=0; j<NumCols; j++ ) {
         fputc( *(cPtr+2), outfile);      // Blue color value
         fputc( *(cPtr+1), outfile);      // Blue color value
         fputc( *(cPtr+0), outfile);      // Blue color value
         cPtr+=3;
      }
      // Pad row to word boundary
      int k=3*NumCols;               // Num bytes already read
      for ( ; k<GetNumBytesPerRow(); k++ ) {
         fputc( 0, outfile );            // Read and ignore padding;
         cPtr++;
      }
   }

   fclose( outfile );   // Close the file
   return true;
}

void RgbImage::writeLong( long data, FILE* outfile )

   // Read in 32 bit integer
   unsigned char byte0, byte1, byte2, byte3;
   byte0 = (unsigned char)(data&0x000000ff);      // Write bytes, low order to high order
   byte1 = (unsigned char)((data>>8)&0x000000ff);
   byte2 = (unsigned char)((data>>16)&0x000000ff);
   byte3 = (unsigned char)((data>>24)&0x000000ff);

   fputc( byte0, outfile );
   fputc( byte1, outfile );
   fputc( byte2, outfile );
   fputc( byte3, outfile );
}

void RgbImage::writeShort( short data, FILE* outfile )

   // Read in 32 bit integer
   unsigned char byte0, byte1;
   byte0 = data&0x000000ff;      // Write bytes, low order to high order
   byte1 = (data>>8)&0x000000ff;

   fputc( byte0, outfile );
   fputc( byte1, outfile );
}


/*********************************************************************
* SetRgbPixel routines allow changing the contents of the RgbImage. *
*********************************************************************/

void RgbImage::SetRgbPixelf( long row, long col, double red, double green, double blue )
{
   SetRgbPixelc( row, col, doubleToUnsignedChar(red),
                     doubleToUnsignedChar(green),
                     doubleToUnsignedChar(blue) );
}

void RgbImage::SetRgbPixelc( long row, long col,
               unsigned char red, unsigned char green, unsigned char blue )
{
   assert ( row<NumRows && col<NumCols );
   unsigned char* thePixel = GetRgbPixel( row, col );
   *(thePixel++) = red;
   *(thePixel++) = green;
   *(thePixel) = blue;
}


unsigned char RgbImage::doubleToUnsignedChar( double x )
{
   if ( x>=1.0 ) {
      return (unsigned char)255;
   }
   else if ( x<=0.0 ) {
      return (unsigned char)0;
   }
   else {
      return (unsigned char)(x*255.0);      // Rounds down
   }
}
// Bitmap file format  (24 bit/pixel form)      BITMAPFILEHEADER
// Header (14 bytes)
//    2 bytes: "BM"
//   4 bytes: long int, file size
//   4 bytes: reserved (actually 2 bytes twice)
//   4 bytes: long int, offset to raster data
// Info header (40 bytes)                  BITMAPINFOHEADER
//   4 bytes: long int, size of info header (=40)
//    4 bytes: long int, bitmap width in pixels
//   4 bytes: long int, bitmap height in pixels
//   2 bytes: short int, number of planes (=1)
//   2 bytes: short int, bits per pixel
//   4 bytes: long int, type of compression (not applicable to 24 bits/pixel)
//   4 bytes: long int, image size (not used unless compression is used)
//   4 bytes: long int, x pixels per meter
//   4 bytes: long int, y pixels per meter
//   4 bytes: colors used (not applicable to 24 bit color)
//   4 bytes: colors important (not applicable to 24 bit color)
// "long int" really means "unsigned long int"
// Pixel data: 3 bytes per pixel: RGB values (in reverse order).
//   Rows padded to multiples of four.


#ifndef RGBIMAGE_DONT_USE_OPENGL

bool RgbImage::LoadFromOpenglBuffer()               // Load the bitmap from the current OpenGL buffer
{
   int viewportData[4];
   glGetIntegerv( GL_VIEWPORT, viewportData );
   int& vWidth = viewportData[2];
   int& vHeight = viewportData[3];
   
   if ( ImagePtr==0 ) { // If no memory allocated
      NumRows = vHeight;
      NumCols = vWidth;
      ImagePtr = new unsigned char[NumRows*GetNumBytesPerRow()];
      if ( !ImagePtr ) {
         fprintf(stderr, "Unable to allocate memory for %ld x %ld buffer.\n",
               NumRows, NumCols);
         Reset();
         ErrorCode = MemoryError;
         return false;
      }
   }
   assert ( vWidth>=NumCols && vHeight>=NumRows );
   int oldGlRowLen;
   if ( vWidth>=NumCols ) {
      glGetIntegerv( GL_UNPACK_ROW_LENGTH, &oldGlRowLen );
      glPixelStorei( GL_UNPACK_ROW_LENGTH, NumCols );
   }
   glPixelStorei(GL_UNPACK_ALIGNMENT, 4);

   // Get the frame buffer data.
   glReadPixels( 0, 0, NumCols, NumRows, GL_RGB, GL_UNSIGNED_BYTE, ImagePtr);

   // Restore the row length in glPixelStorei  (really ought to restore alignment too).
   if ( vWidth>=NumCols ) {
      glPixelStorei( GL_UNPACK_ROW_LENGTH, oldGlRowLen );
   }   
   return true;
}

#endif   // RGBIMAGE_DONT_USE_OPENGL



RgbImage.h :
Code:
/*
*
* RayTrace Software Package, release 1.0.4,  February 2004.
*
* Author: Samuel R. Buss
*
* Software accompanying the book
*      3D Computer Graphics: A Mathematical Introduction with OpenGL,
*      by S. Buss, Cambridge University Press, 2003.
*
* Software is "as-is" and carries no warranty.  It may be used without
*   restriction, but if you modify it, please change the filenames to
*   prevent confusion between different versions.  Please acknowledge
*   all use of the software in any publications or products based on it.
*
* Bug reports: Sam Buss, sbuss@ucsd.edu.
* Web page: http://math.ucsd.edu/~sbuss/MathCG
*
*/

#ifndef RGBIMAGE_H
#define RGBIMAGE_H

#include <stdio.h>
#include <assert.h>

// Include the next line to turn off the routines that use OpenGL
// #define RGBIMAGE_DONT_USE_OPENGL

class RgbImage
{
public:
   RgbImage();
   RgbImage( const char* filename );
   RgbImage( int numRows, int numCols );   // Initialize a blank bitmap of this size.
   ~RgbImage();

   bool LoadBmpFile( const char *filename );      // Loads the bitmap from the specified file
   bool WriteBmpFile( const char* filename );      // Write the bitmap to the specified file
#ifndef RGBIMAGE_DONT_USE_OPENGL
   bool LoadFromOpenglBuffer();               // Load the bitmap from the current OpenGL buffer
#endif

   long GetNumRows() const { return NumRows; }
   long GetNumCols() const { return NumCols; }
   // Rows are word aligned
   long GetNumBytesPerRow() const { return ((3*NumCols+3)>>2)<<2; }   
   const void* ImageData() const { return (void*)ImagePtr; }

   const unsigned char* GetRgbPixel( long row, long col ) const;
   unsigned char* GetRgbPixel( long row, long col );
   void GetRgbPixel( long row, long col, float* red, float* green, float* blue ) const;
   void GetRgbPixel( long row, long col, double* red, double* green, double* blue ) const;

   void SetRgbPixelf( long row, long col, double red, double green, double blue );
   void SetRgbPixelc( long row, long col,
                  unsigned char red, unsigned char green, unsigned char blue );

   // Error reporting. (errors also print message to stderr)
   int GetErrorCode() const { return ErrorCode; }
   enum {
      NoError = 0,
      OpenError = 1,         // Unable to open file for reading
      FileFormatError = 2,   // Not recognized as a 24 bit BMP file
      MemoryError = 3,      // Unable to allocate memory for image data
      ReadError = 4,         // End of file reached prematurely
      WriteError = 5         // Unable to write out data (or no date to write out)
   };
   bool ImageLoaded() const { return (ImagePtr!=0); }  // Is an image loaded?

   void Reset();         // Frees image data memory

private:
   unsigned char* ImagePtr;   // array of pixel values (integers range 0 to 255)
   long NumRows;            // number of rows in image
   long NumCols;            // number of columns in image
   int ErrorCode;            // error code

   static short readShort( FILE* infile );
   static long readLong( FILE* infile );
   static void skipChars( FILE* infile, int numChars );
   static void RgbImage::writeLong( long data, FILE* outfile );
   static void RgbImage::writeShort( short data, FILE* outfile );
   
   static unsigned char doubleToUnsignedChar( double x );

};

inline RgbImage::RgbImage()
{
   NumRows = 0;
   NumCols = 0;
   ImagePtr = 0;
   ErrorCode = 0;
}

inline RgbImage::RgbImage( const char* filename )
{
   NumRows = 0;
   NumCols = 0;
   ImagePtr = 0;
   ErrorCode = 0;
   LoadBmpFile( filename );
}

inline RgbImage::~RgbImage()
{
   delete[] ImagePtr;
}

// Returned value points to three "unsigned char" values for R,G,B
inline const unsigned char* RgbImage::GetRgbPixel( long row, long col ) const
{
   assert ( row<NumRows && col<NumCols );
   const unsigned char* ret = ImagePtr;
   long i = row*GetNumBytesPerRow() + 3*col;
   ret += i;
   return ret;
}

inline unsigned char* RgbImage::GetRgbPixel( long row, long col )
{
   assert ( row<NumRows && col<NumCols );
   unsigned char* ret = ImagePtr;
   long i = row*GetNumBytesPerRow() + 3*col;
   ret += i;
   return ret;
}

inline void RgbImage::GetRgbPixel( long row, long col, float* red, float* green, float* blue ) const
{
   assert ( row<NumRows && col<NumCols );
   const unsigned char* thePixel = GetRgbPixel( row, col );
   const float f = 1.0f/255.0f;
   *red = f*(float)(*(thePixel++));
   *green = f*(float)(*(thePixel++));
   *blue = f*(float)(*thePixel);
}

inline void RgbImage::GetRgbPixel( long row, long col, double* red, double* green, double* blue ) const
{
   assert ( row<NumRows && col<NumCols );
   const unsigned char* thePixel = GetRgbPixel( row, col );
   const double f = 1.0/255.0;
   *red = f*(double)(*(thePixel++));
   *green = f*(double)(*(thePixel++));
   *blue = f*(double)(*thePixel);
}

inline void RgbImage::Reset()
{
   NumRows = 0;
   NumCols = 0;
   delete[] ImagePtr;
   ImagePtr = 0;
   ErrorCode = 0;
}


#endif // RGBIMAGE_H



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