Texture.cpp

#include "Texture.h"

#ifdef __APPLE__
    #include <GLUT/glut.h>
#else
    #include <GL/glut.h>
#endif


Texture* Texture::emptyTexture = new Texture();

Texture::Texture()
{
    id = 0;
}

Texture::Texture(const char* fname)
{
    filename = fname;
    
    GLuint texture[1];     // storage for one texture
    int twidth, theight;   // texture width/height [pixels]
    unsigned char* tdata;  // texture pixel data
    
    // Load image file
    tdata = loadPPM(filename, twidth, theight);
    
    //If the image wasn't loaded, can't continue
    if(tdata == NULL)
        return;
    
    // Create ID for texture
    glGenTextures(1, &texture[0]);
    id=texture[0];
    
    // Set this texture to be the one we are working with
    glBindTexture(GL_TEXTURE_2D, texture[0]);
    
    // Generate the texture
    glTexImage2D(GL_TEXTURE_2D, 0, 3, twidth, theight, 0, GL_RGB, GL_UNSIGNED_BYTE, tdata);
    
    // Make sure no bytes are padded:
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    
    // Select GL_MODULATE to mix texture with quad color for shading:
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    
    // Use bilinear interpolation:
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    
    glBindTexture(GL_TEXTURE_2D, 0);
}

Texture::~Texture()
{
    //
}

void Texture::bind(void)
{
    glBindTexture(GL_TEXTURE_2D, id);
}

void Texture::unbind(void)
{
    glBindTexture(GL_TEXTURE_2D, 0);
}

/** Load a ppm file from disk.
 @input filename The location of the PPM file.  If the file is not found, an error message
 will be printed and this function will return 0
 @input width This will be modified to contain the width of the loaded image, or 0 if file not found
 @input height This will be modified to contain the height of the loaded image, or 0 if file not found
 @return Returns the RGB pixel data as interleaved unsigned chars (R0 G0 B0 R1 G1 B1 R2 G2 B2 .... etc) or 0 if an error ocured
 **/
unsigned char* Texture::loadPPM(const char* filename, int& width, int& height)
{
    const int BUFSIZE = 128;
    FILE* fp;
    size_t read;
    unsigned char* rawData;
    char buf[3][BUFSIZE];
    char* retval_fgets;
    size_t retval_sscanf;
    
    //Open the texture file
    if((fp=fopen(filename, "rb")) == NULL)
    {
        std::cerr << "error reading ppm file, could not locate " << filename << std::endl;
        width = 0;
        height = 0;
        return NULL;
    }
    
    // Read magic number:
    retval_fgets = fgets(buf[0], BUFSIZE, fp);
    
    // Read width and height:
    do
    {
        retval_fgets=fgets(buf[0], BUFSIZE, fp);
    } while (buf[0][0] == '#');
    
    retval_sscanf=sscanf(buf[0], "%s %s", buf[1], buf[2]);
    width  = atoi(buf[1]);
    height = atoi(buf[2]);
    
    // Read maxval:
    do
    {
        retval_fgets=fgets(buf[0], BUFSIZE, fp);
    } while (buf[0][0] == '#');
    
    // Read image data:
    rawData = new unsigned char[width * height * 3];
    read = fread(rawData, width * height * 3, 1, fp);
    fclose(fp);
    if (read != 1)
    {
        std::cerr << "error parsing ppm file, incomplete data" << std::endl;
        delete[] rawData;
        width = 0;
        height = 0;
        return NULL;
    }
    
    return rawData;
}