Question

#include <stdio.h>
#include <GL/gl.h>
#include <GL/glut.h>

#define KEY_ESCAPE 27

void display();
void keyboard(unsigned char,int,int);
GLuint LoadTextureRAW( const char * filename, int wrap );

int main(int argc, char **argv) {
    glutInit(&argc, argv);                                    
    glutInitDisplayMode(GLUT_RGB|GLUT_DOUBLE|GLUT_DEPTH );
    glutInitWindowSize(600,400);                  
    glutCreateWindow("Opengl Test");                              
    glutDisplayFunc(display);
    glutKeyboardFunc(keyboard);
    glutMainLoop();
    return 0;
}
void display() {
    GLuint texture=LoadTextureRAW("ball.png",1);
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D,texture);
    glBegin( GL_QUADS );
    glTexCoord2d(0.0,0.0); glVertex2d(0.0,0.0);
    glTexCoord2d(1.0,0.0); glVertex2d(1.0,0.0);
    glTexCoord2d(1.0,1.0); glVertex2d(1.0,1.0);
    glTexCoord2d(0.0,1.0); glVertex2d(0.0,1.0);
    glEnd();
    glutSwapBuffers();    
}
// load a 256x256 RGB .RAW file as a texture
GLuint LoadTextureRAW( const char * filename, int wrap )
{
    GLuint texture;
    int width, height;
//    BYTE * data;
    int *data;
    FILE * file;

    // open texture data
    file = fopen( filename, "rb" );
    if ( file == NULL ) return 0;

    // allocate buffer
    width = 256;
    height = 256;
    data = (int*)malloc( width * height * 3 );

    // read texture data
    fread( data, width * height * 3, 1, file );
    fclose( file );

    // allocate a texture name
    glGenTextures( 1, &texture );

    // select our current texture
    glBindTexture( GL_TEXTURE_2D, texture );

    // select modulate to mix texture with color for shading
    glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );

    // when texture area is small, bilinear filter the closest mipmap
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
                     GL_LINEAR_MIPMAP_NEAREST );
    // when texture area is large, bilinear filter the first mipmap
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );

    // if wrap is true, the texture wraps over at the edges (repeat)
    //       ... false, the texture ends at the edges (clamp)
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,
                     wrap ? GL_REPEAT : GL_CLAMP );
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,
                     wrap ? GL_REPEAT : GL_CLAMP );

    // build our texture mipmaps
    gluBuild2DMipmaps( GL_TEXTURE_2D, 3, width, height,
                       GL_RGB, GL_UNSIGNED_BYTE, data );

    // free buffer
    free( data );

    return texture;
}
void keyboard(unsigned char key, int mousePositionX, int mousePositionY) { 
    switch ( key ) {
        case KEY_ESCAPE:
            exit ( 0 );   
            break;      
        default:      
            break;
    }
}

I followed this, http://www.nullterminator.net/gltexture.html

What should i do?

Answer 1

“LoadTextureRAW()” is not for PNG files. You will need a third party library like libpng to decode a png file, because they are compressed.

If you don’t want to implement libpng yourself, which is kind of advanced, then you can probably find a wrapper library on google somewhere.

You can find a minimal implementation of libpng here:
http://zarb.org/~gc/html/libpng.html