Elysian Shadows

Code: Select all

GLuint LoadBMP(const char*file)
{
	ifstream File;
	char shortbuffer[2], intbuffer[4];
	unsigned int Offset=NULL;
	unsigned int header=NULL;
	signed int width=NULL;
	signed int height=NULL;
	int bpr=NULL;
	int size=NULL;
	
	File.open(file,ifstream::binary);
	File.read(shortbuffer,2); //format check
	if(shortbuffer[0]!='B'||shortbuffer[1]!='M')
	{
		File.close();
		assert(!"Error 1");
		return NULL;
	}
	File.ignore(8); //skip the next 4,2 and 2 bytes
	//get buffer offset for pixel data
	File.read(intbuffer,4);
	Offset=(((unsigned char)intbuffer[3]<<24)|
			((unsigned char)intbuffer[2]<<16)|
			((unsigned char)intbuffer[1]<<8)|
			((unsigned char)intbuffer[0]));
	intbuffer={0,0,0,0};
	File.read(intbuffer,4);
	header=(((unsigned char)intbuffer[3]<<24)|
			((unsigned char)intbuffer[2]<<16)|
			((unsigned char)intbuffer[1]<<8)|
			((unsigned char)intbuffer[0]));
	intbuffer={0,0,0,0};
	if(header!=40)
	{
		File.close();
		assert(!"Error 2");
		return NULL;
	}
	File.read(intbuffer,4);
	width=(((unsigned char)intbuffer[3]<<24)|
			((unsigned char)intbuffer[2]<<16)|
			((unsigned char)intbuffer[1]<<8)|
			((unsigned char)intbuffer[0]));
	File.read(intbuffer,4);
	height=(((unsigned char)intbuffer[3]<<24)| //shift in reverse order becuase they were written from left to right maybe?
			((unsigned char)intbuffer[2]<<16)|
			((unsigned char)intbuffer[1]<<8)|
			((unsigned char)intbuffer[0]));
	
	bpr=((width * 3 + 3) / 4) * 4 - (width * 3 % 4); //dont get this
	size=bpr*height;
	
	char*buffer=new char[size];
	char*data=new char[width*height*3];
	
	File.seekg(Offset,std::ios_base::beg);
	File.read(buffer,size);
	
	for(int y=0;y<height;y++)
	{
		for(int x=0;x<width;x++)
		{
			for(int c=0;c<3;c++)
			{
				data[3 * (width * y + x) + c]=buffer[bpr * y + 3 * x + (2 - c)]; //dont get this either...
			}
		}
	}
	File.close();
	delete [] buffer;
	GLuint Texture;
	glGenTextures(1,&Texture);
	glBindTexture(GL_TEXTURE_2D,Texture);
	
	glTexImage2D(GL_TEXTURE_2D,0,3,width,height,0,GL_BGR,GL_UNSIGNED_BYTE,data);
	glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
    glFinish();
    delete [] data;
	return Texture;
}

Code: Select all

typedef struct
{
    unsigned short type;                     // Will code out to 0x4D42 which is 19778 in decimal. This equates to "BM" in 8 bit ASCII
    unsigned int     size;                     // This is the size of the chunk
    unsigned short  reserved1;            // Reserved
    unsigned short  reserved2;            // Reserved
    unsigned int      offsetBits;            // pixmap offset (in bytes from beginning of file)
} s_bitmap_header;


typedef struct
{
    unsigned int      bmpSize;               // Pixmap size (bytes)
    int                    bmpWidth;            // Pixmap width (pixels)
    int                    bmpHeight;           // Pixmap height (pixels)
    unsigned short   bmpPlanes;           // Image bitplanes
    unsigned short   bmpBitDepth;        // Image depth (bits per pixel)     <--- important
    unsigned int       bmpCompress;      // Compression tag
    unsigned int       bmpImageSize;      // Physical size
    int                     bmpXPixelsPerMeter;     // Physical size in meters on x
    int                     bmpYPixelsPerMeter;     // Physical size in meters on y
    unsigned int       bmpClrUsed;              
    unsigned int       bmpClrImportant;          
} s_bitmap_info_header;

Code: Select all

// Assuming you have a valid FILE
FILE* bmpFile;
if( ( bmpFile = fopen( fileName, "rb" ) ) == NULL )
        return false;  //gtfo


// Read Header //
s_bitmap_header fHeader;
fread( &fHeader, sizeof( s_bitmap_header ), 1, bmpFile ); 

// Magic number doesnt check out //
if( fHeader.type != 19778 )
{
      fclose( bmpFile );
      return false;
}

// Read second header //
s_bitmap_info_header fInfoHeader;
fread( &fInfoHeader, sizeof( s_bitmap_info_header ), 1, bmpFile );

int imgWidth = fInfoHeader.bmpWidth;
int imgHeight = fInfoHeader.bmpHeight;
int bpp           = fInfoHeader.bmpBitDepth;

// Allocate the pixmap //
unsigned int pixmapSize = imgWidth * imgHeight * ( bpp / 8 );          // bpp / 8 yields size in bytes
unsigned char* pix = new unsigned char[pixmapSize];

// Read pixmap into buffer //
fread( pix, sizeof( unsigned char ), totalSize, bmpFile );

// Ba-da-bing....clean up your shit, do whatever else you have to do, and done //
}