magic1.cpp

3D Game Engine Design Source Code非常棒

#include <stdio.h>
#include <string.h>
#include "elements.h"
#include "fileform.h"
#include "magic1.h"

int FT_MAGIC1;

//===========================================================================
static int
MAGIC1_query (char* name)
{
	FILE *input = fopen(name,"rb");
	if ( !input )
		return -1;

	char buffer[6];
	fread(buffer,sizeof(char),5,input);
	buffer[5] = 0;
	fclose(input);

	if ( strcmp(buffer,"dims=") == 0 )
		return 1;
	else
		return 0;
}
//---------------------------------------------------------------------------
static int
MAGIC1_gethead (char* name, int* dims, int** dim, char* elform,
	int* order)
{
	FILE *input = fopen(name,"rb");
	if ( !input )
		return 0;

	// read dimension information
	fscanf(input,"dims=%d\r\n",dims);

	// size of each dimension
	*dim = new int[*dims];  // assumes *dim is a valid address
	for (int i = 0; i < *dims; i++) {
		int dummy;
		fscanf(input,"dim[%d]=%d\r\n",&dummy,&((*dim)[i]));
	}

	// read element type information
	int eltype;
	fscanf(input,"type=%d\r\n\x1a",&eltype);
	strcpy(elform,mgcElementDBM::Description(eltype));

	*order = 0;

	fclose(input);
	return 1;
}
//---------------------------------------------------------------------------
static int
MAGIC1_puthead (char* name, int dims, const int* dim, const char* elform,
	int)
{
	FILE *output = fopen(name,"wb");
	if ( !output )
		return 0;

	// write dimension information
	fprintf(output,"dims=%d\r\n",dims);
	int i;
	for (i = 0; i < dims; i++)
		fprintf(output,"dim[%d]=%d\r\n",i,dim[i]);

	// write element type information
	int eltype = mgcElementDBM::Type(elform);
	fprintf(output,"type=%d\r\n",eltype);
	fprintf(output,"\x1a");  // terminate with ASCII EOF character

	// allocate file space to hold all the elements
	const int buffer_size = 16384;
	char* buffer = new char[buffer_size];
	for (i = 0; i < buffer_size; i++)
		buffer[i] = 0;

	int quantity = 1;
	for (i = 0; i < dims; i++)
		quantity *= dim[i];

	int byte_quantity = quantity*mgcElementDBM::PackedSize(eltype);
	int block_count = byte_quantity / buffer_size;
	int block_remainder = byte_quantity % buffer_size;
	for (i = 0; i < block_count; i++)
		fwrite(buffer,sizeof(char),buffer_size,output);
	if ( block_remainder )
		fwrite(buffer,sizeof(char),block_remainder,output);

	delete[] buffer;
	fclose(output);
	return 1;
}
//---------------------------------------------------------------------------
static int
MAGIC1_getdata (char* name, long offset, int quantity, char* buffer)
{
	FILE* file = fopen(name,"r+b");
	if ( !file )
		return 0;

	// move file pointer to first element of buffer
	fseek(file,0,0);
	char c = 0;
	while ( c != '\x1a' )
		fread(&c,sizeof(char),1,file);

	fseek(file,offset,1);  // seek from current
	fread(buffer,sizeof(char),quantity,file);
	fclose(file);

	return 1;
}
//---------------------------------------------------------------------------
static int
MAGIC1_putdata (char* name, long offset, int quantity, char* buffer)
{
	FILE* file = fopen(name,"r+b");
	if ( !file )
		return 0;

	// move file pointer to first element of buffer
	fseek(file,0,0);
	char c = 0;
	while ( c != '\x1a' )
		fread(&c,sizeof(char),1,file);

	fseek(file,offset,1);  // seek from current
	fwrite(buffer,sizeof(char),quantity,file);
	fclose(file);

	return 1;
}
//---------------------------------------------------------------------------
static int
MAGIC1_getmessage (char*, void*)
{
	return 0;
}
//---------------------------------------------------------------------------
static int
MAGIC1_putmessage (char*, void*)
{
	return 0;
}
//---------------------------------------------------------------------------
int __MAGIC1_register__()
{
	// automatic registration of MAGIC1 file format
	static int is_registered = 0;

	if ( is_registered == 0 ) {
		FT_MAGIC1 = mgcFileFormat::AddFileFormat(
			MAGIC1_query,
			MAGIC1_gethead,
			MAGIC1_puthead,
			MAGIC1_getdata,
			MAGIC1_putdata,
			MAGIC1_getmessage,
			MAGIC1_putmessage
	    );
		is_registered = 1;
	}
	return is_registered;
}
//===========================================================================