source: GTP/trunk/Lib/Geom/shared/GTGeometry/src/libs/vmi/src/LoadTGA.cpp @ 983

// LoadTGA.c
// Loads a Targa file for OpenGL
// Richard S. Wright Jr.
// OpenGL SuperBible
// This really only works with 24/32/8 bit targas

#include <stdio.h>
#include <stdlib.h>

#include "../include/GL/glew.h"
#include "../include/TGA.h"

////////////////////////////////////////////////////////////////////
// Allocate memory and load targa bits. Returns pointer to new buffer,
// height, and width of texture, and the OpenGL format of data.
// Call free() on buffer when finished!
// This only works on pretty vanilla targas... 8, 24, or 32 bit color
// only, no palettes, no RLE encoding.
GLbyte *gltLoadTGA(const char *szFileName, GLint *iWidth, GLint *iHeight, GLint *iComponents, GLenum *eFormat)
    {
    FILE *pFile;                // File pointer
    TGAHEADER tgaHeader;        // TGA file header
    unsigned long lImageSize;   // Size in bytes of image
    short sDepth;               // Pixel depth;
    GLbyte  *pBits = NULL;      // Pointer to bits
    
    // Default/Failed values
    *iWidth = 0;
    *iHeight = 0;
    *eFormat = GL_BGR_EXT;
    *iComponents = GL_RGB8;
    
    // Attempt to open the fil
    pFile = fopen(szFileName, "rb");
    if(pFile == NULL)
        return NULL;
        
    // Read in header (binary)
    fread(&tgaHeader, 18/* sizeof(TGAHEADER)*/, 1, pFile);
    
    // Do byte swap for big vs little endian
#ifdef __APPLE__
    BYTE_SWAP(tgaHeader.colorMapStart);
    BYTE_SWAP(tgaHeader.colorMapLength);
    BYTE_SWAP(tgaHeader.xstart);
    BYTE_SWAP(tgaHeader.ystart);
    BYTE_SWAP(tgaHeader.width);
    BYTE_SWAP(tgaHeader.height);
#endif

        
    // Get width, height, and depth of texture
    *iWidth = tgaHeader.width;
    *iHeight = tgaHeader.height;
    sDepth = tgaHeader.bits / 8;
    
    // Put some validity checks here. Very simply, I only understand
    // or care about 8, 24, or 32 bit targa's.
    if(tgaHeader.bits != 8 && tgaHeader.bits != 24 && tgaHeader.bits != 32)
        return NULL;

    // Calculate size of image buffer
    lImageSize = tgaHeader.width * tgaHeader.height * sDepth;
    
    // Allocate memory and check for success
    pBits = (GLbyte *)malloc(lImageSize * sizeof(GLbyte));
    if(pBits == NULL)
        return NULL;
    
    // Read in the bits
    // Check for read error. This should catch RLE or other 
    // weird formats that I don't want to recognize
    if(fread(pBits, lImageSize, 1, pFile) != 1)
        {
        free(pBits);
        return NULL;
        }
    
    // Set OpenGL format expected
    switch(sDepth)
        {
        case 3:     // Most likely case
            *eFormat = GL_BGR_EXT;
            *iComponents = GL_RGB8;
            break;
        case 4:
            *eFormat = GL_BGRA_EXT;
            *iComponents = GL_RGBA8;
            break;
        case 1:
            *eFormat = GL_LUMINANCE;
            *iComponents = GL_LUMINANCE8;
            break;
        };
        
    
    // Done with File
    fclose(pFile);
        
    // Return pointer to image data
    return pBits;
    }