?? tgaloader.cpp
字號:
/********************************************************************************
/Name: TGA.cpp *
/Header: tga.h *
/Purpose: Load Compressed and Uncompressed TGA files *
/Functions: LoadTGA(Texture * texture, char * filename) *
/ LoadCompressedTGA(Texture * texture, char * filename, FILE * fTGA) *
/ LoadUncompressedTGA(Texture * texture, char * filename, FILE * fTGA)*
/*******************************************************************************/
#include "tga.h"
/********************************************************************************
/name : LoadTGA(Texture * texture, char * filename) *
/function: Open and test the file to make sure it is a valid TGA file *
/parems: texture, pointer to a Texture structure *
/ filename, string pointing to file to open *
/********************************************************************************/
bool LoadTGA(Texture * texture, char * filename) // Load a TGA file
{
FILE * fTGA; // File pointer to texture file
fTGA = fopen(filename, "rb"); // Open file for reading
if(fTGA == NULL) // If it didn't open....
{
MessageBox(NULL, "Could not open texture file", "ERROR", MB_OK); // Display an error message
return false; // Exit function
}
if(fread(&tgaheader, sizeof(TGAHeader), 1, fTGA) == 0) // Attempt to read 12 byte header from file
{
MessageBox(NULL, "Could not read file header", "ERROR", MB_OK); // If it fails, display an error message
if(fTGA != NULL) // Check to seeiffile is still open
{
fclose(fTGA); // If it is, close it
}
return false; // Exit function
}
if(memcmp(uTGAcompare, &tgaheader, sizeof(tgaheader)) == 0) // See if header matches the predefined header of
{ // an Uncompressed TGA image
LoadUncompressedTGA(texture, filename, fTGA); // If so, jump to Uncompressed TGA loading code
}
else if(memcmp(cTGAcompare, &tgaheader, sizeof(tgaheader)) == 0) // See if header matches the predefined header of
{ // an RLE compressed TGA image
LoadCompressedTGA(texture, filename, fTGA); // If so, jump to Compressed TGA loading code
}
else // If header matches neither type
{
MessageBox(NULL, "TGA file be type 2 or type 10 ", "Invalid Image", MB_OK); // Display an error
fclose(fTGA);
return false; // Exit function
}
return true; // All went well, continue on
}
bool LoadUncompressedTGA(Texture * texture, char * filename, FILE * fTGA) // Load an uncompressed TGA (note, much of this code is based on NeHe's
{ // TGA Loading code nehe.gamedev.net)
if(fread(tga.header, sizeof(tga.header), 1, fTGA) == 0) // Read TGA header
{
MessageBox(NULL, "Could not read info header", "ERROR", MB_OK); // Display error
if(fTGA != NULL) // if file is still open
{
fclose(fTGA); // Close it
}
return false; // Return failular
}
texture->width = tga.header[1] * 256 + tga.header[0]; // Determine The TGA Width (highbyte*256+lowbyte)
texture->height = tga.header[3] * 256 + tga.header[2]; // Determine The TGA Height (highbyte*256+lowbyte)
texture->bpp = tga.header[4]; // Determine the bits per pixel
tga.Width = texture->width; // Copy width into local structure
tga.Height = texture->height; // Copy height into local structure
tga.Bpp = texture->bpp; // Copy BPP into local structure
if((texture->width <= 0) || (texture->height <= 0) || ((texture->bpp != 24) && (texture->bpp !=32))) // Make sure all information is valid
{
MessageBox(NULL, "Invalid texture information", "ERROR", MB_OK); // Display Error
if(fTGA != NULL) // Check if file is still open
{
fclose(fTGA); // If so, close it
}
return false; // Return failed
}
if(texture->bpp == 24) // If the BPP of the image is 24...
texture->type = GL_RGB; // Set Image type to GL_RGB
else // Else if its 32 BPP
texture->type = GL_RGBA; // Set image type to GL_RGBA
tga.bytesPerPixel = (tga.Bpp / 8); // Compute the number of BYTES per pixel
tga.imageSize = (tga.bytesPerPixel * tga.Width * tga.Height); // Compute the total amout ofmemory needed to store data
texture->imageData = (GLubyte *)malloc(tga.imageSize); // Allocate that much memory
if(texture->imageData == NULL) // If no space was allocated
{
MessageBox(NULL, "Could not allocate memory for image", "ERROR", MB_OK); // Display Error
fclose(fTGA); // Close the file
return false; // Return failed
}
if(fread(texture->imageData, 1, tga.imageSize, fTGA) != tga.imageSize) // Attempt to read image data
{
MessageBox(NULL, "Could not read image data", "ERROR", MB_OK); // Display Error
if(texture->imageData != NULL) // If imagedata has data in it
{
free(texture->imageData); // Delete data from memory
}
fclose(fTGA); // Close file
return false; // Return failed
}
// Byte Swapping Optimized By Steve Thomas
for(GLuint cswap = 0; cswap < (int)tga.imageSize; cswap += tga.bytesPerPixel)
{
texture->imageData[cswap] ^= texture->imageData[cswap+2] ^=
texture->imageData[cswap] ^= texture->imageData[cswap+2];
}
fclose(fTGA); // Close file
return true; // Return success
}
bool LoadCompressedTGA(Texture * texture, char * filename, FILE * fTGA) // Load COMPRESSED TGAs
{
if(fread(tga.header, sizeof(tga.header), 1, fTGA) == 0) // Attempt to read header
{
MessageBox(NULL, "Could not read info header", "ERROR", MB_OK); // Display Error
if(fTGA != NULL) // If file is open
{
fclose(fTGA); // Close it
}
return false; // Return failed
}
texture->width = tga.header[1] * 256 + tga.header[0]; // Determine The TGA Width (highbyte*256+lowbyte)
texture->height = tga.header[3] * 256 + tga.header[2]; // Determine The TGA Height (highbyte*256+lowbyte)
texture->bpp = tga.header[4]; // Determine Bits Per Pixel
tga.Width = texture->width; // Copy width to local structure
tga.Height = texture->height; // Copy width to local structure
tga.Bpp = texture->bpp; // Copy width to local structure
if((texture->width <= 0) || (texture->height <= 0) || ((texture->bpp != 24) && (texture->bpp !=32))) //Make sure all texture info is ok
{
MessageBox(NULL, "Invalid texture information", "ERROR", MB_OK); // If it isnt...Display error
if(fTGA != NULL) // Check if file is open
{
fclose(fTGA); // Ifit is, close it
}
return false; // Return failed
}
if(texture->bpp == 24) // If the BPP of the image is 24...
texture->type = GL_RGB; // Set Image type to GL_RGB
else // Else if its 32 BPP
texture->type = GL_RGBA; // Set image type to GL_RGBA
tga.bytesPerPixel = (tga.Bpp / 8); // Compute BYTES per pixel
tga.imageSize = (tga.bytesPerPixel * tga.Width * tga.Height); // Compute amout of memory needed to store image
texture->imageData = (GLubyte *)malloc(tga.imageSize); // Allocate that much memory
if(texture->imageData == NULL) // If it wasnt allocated correctly..
{
MessageBox(NULL, "Could not allocate memory for image", "ERROR", MB_OK); // Display Error
fclose(fTGA); // Close file
return false; // Return failed
}
GLuint pixelcount = tga.Height * tga.Width; // Nuber of pixels in the image
GLuint currentpixel = 0; // Current pixel being read
GLuint currentbyte = 0; // Current byte
GLubyte * colorbuffer = (GLubyte *)malloc(tga.bytesPerPixel); // Storage for 1 pixel
do
{
GLubyte chunkheader = 0; // Storage for "chunk" header
if(fread(&chunkheader, sizeof(GLubyte), 1, fTGA) == 0) // Read in the 1 byte header
{
MessageBox(NULL, "Could not read RLE header", "ERROR", MB_OK); // Display Error
if(fTGA != NULL) // If file is open
{
fclose(fTGA); // Close file
}
if(texture->imageData != NULL) // If there is stored image data
{
free(texture->imageData); // Delete image data
}
return false; // Return failed
}
if(chunkheader < 128) // If the ehader is < 128, it means the that is the number of RAW color packets minus 1
{ // that follow the header
chunkheader++; // add 1 to get number of following color values
for(short counter = 0; counter < chunkheader; counter++) // Read RAW color values
{
if(fread(colorbuffer, 1, tga.bytesPerPixel, fTGA) != tga.bytesPerPixel) // Try to read 1 pixel
{
MessageBox(NULL, "Could not read image data", "ERROR", MB_OK); // IF we cant, display an error
if(fTGA != NULL) // See if file is open
{
fclose(fTGA); // If so, close file
}
if(colorbuffer != NULL) // See if colorbuffer has data in it
{
free(colorbuffer); // If so, delete it
}
if(texture->imageData != NULL) // See if there is stored Image data
{
free(texture->imageData); // If so, delete it too
}
return false; // Return failed
}
// write to memory
texture->imageData[currentbyte ] = colorbuffer[2]; // Flip R and B vcolor values around in the process
texture->imageData[currentbyte + 1 ] = colorbuffer[1];
texture->imageData[currentbyte + 2 ] = colorbuffer[0];
if(tga.bytesPerPixel == 4) // if its a 32 bpp image
{
texture->imageData[currentbyte + 3] = colorbuffer[3]; // copy the 4th byte
}
currentbyte += tga.bytesPerPixel; // Increase thecurrent byte by the number of bytes per pixel
currentpixel++; // Increase current pixel by 1
if(currentpixel > pixelcount) // Make sure we havent read too many pixels
{
MessageBox(NULL, "Too many pixels read", "ERROR", NULL); // if there is too many... Display an error!
if(fTGA != NULL) // If there is a file open
{
fclose(fTGA); // Close file
}
if(colorbuffer != NULL) // If there is data in colorbuffer
{
free(colorbuffer); // Delete it
}
if(texture->imageData != NULL) // If there is Image data
{
free(texture->imageData); // delete it
}
return false; // Return failed
}
}
}
else // chunkheader > 128 RLE data, next color reapeated chunkheader - 127 times
{
chunkheader -= 127; // Subteact 127 to get rid of the ID bit
if(fread(colorbuffer, 1, tga.bytesPerPixel, fTGA) != tga.bytesPerPixel) // Attempt to read following color values
{
MessageBox(NULL, "Could not read from file", "ERROR", MB_OK); // If attempt fails.. Display error (again)
if(fTGA != NULL) // If thereis a file open
{
fclose(fTGA); // Close it
}
if(colorbuffer != NULL) // If there is data in the colorbuffer
{
free(colorbuffer); // delete it
}
if(texture->imageData != NULL) // If thereis image data
{
free(texture->imageData); // delete it
}
return false; // return failed
}
for(short counter = 0; counter < chunkheader; counter++) // copy the color into the image data as many times as dictated
{ // by the header
texture->imageData[currentbyte ] = colorbuffer[2]; // switch R and B bytes areound while copying
texture->imageData[currentbyte + 1 ] = colorbuffer[1];
texture->imageData[currentbyte + 2 ] = colorbuffer[0];
if(tga.bytesPerPixel == 4) // If TGA images is 32 bpp
{
texture->imageData[currentbyte + 3] = colorbuffer[3]; // Copy 4th byte
}
currentbyte += tga.bytesPerPixel; // Increase current byte by the number of bytes per pixel
currentpixel++; // Increase pixel count by 1
if(currentpixel > pixelcount) // Make sure we havent written too many pixels
{
MessageBox(NULL, "Too many pixels read", "ERROR", NULL); // if there is too many... Display an error!
if(fTGA != NULL) // If there is a file open
{
fclose(fTGA); // Close file
}
if(colorbuffer != NULL) // If there is data in colorbuffer
{
free(colorbuffer); // Delete it
}
if(texture->imageData != NULL) // If there is Image data
{
free(texture->imageData); // delete it
}
return false; // Return failed
}
}
}
}
while(currentpixel < pixelcount); // Loop while there are still pixels left
fclose(fTGA); // Close the file
return true; // return success
}
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