I am working on a graphics project I want to make a city using opengl with c++ anyway in the last few days I have been trying to load a texture but it didn't work with me in any way I have tried many codes and tried to follow some tutorials but it didn't went ok
here is my load texture function:
int LoadTexture(char *filename,int alpha)
{
int i, j=0; //Index variables
FILE *l_file; //File pointer
unsigned char *l_texture; //The pointer to the memory zone in which we will load the texture
// windows.h gives us these types to work with the Bitmap files
BITMAPFILEHEADER fileheader;
BITMAPINFOHEADER infoheader;
RGBTRIPLE rgb;
num_texture++; // The counter of the current texture is increased
if( (l_file = fopen(filename, "rb"))==NULL) return (-1); // Open the file for reading
fread(&fileheader, sizeof(fileheader), 1, l_file); // Read the fileheader
fseek(l_file, sizeof(fileheader), SEEK_SET); // Jump the fileheader
fread(&infoheader, sizeof(infoheader), 1, l_file); // and read the infoheader
// Now we need to allocate the memory for our image (width * height * color deep)
l_texture = (byte *) malloc(infoheader.biWidth * infoheader.biHeight * 4);
// And fill it with zeros
memset(l_texture, 0, infoheader.biWidth * infoheader.biHeight * 4);
// At this point we can read every pixel of the image
for (i=0; i < infoheader.biWidth*infoheader.biHeight; i++)
{
// We load an RGB value from the file
fread(&rgb, sizeof(rgb), 1, l_file);
// And store it
l_texture[j+0] = rgb.rgbtRed; // Red component
l_texture[j+1] = rgb.rgbtGreen; // Green component
l_texture[j+2] = rgb.rgbtBlue; // Blue component
l_texture[j+3] = alpha; // Alpha value
j += 4; // Go to the next position
}
fclose(l_file); // Closes the file stream
glBindTexture(GL_TEXTURE_2D, num_texture); // Bind the ID texture specified by the 2nd parameter
// The next commands sets the texture parameters
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); // If the u,v coordinates overflow the range 0,1 the image is repeated
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); // The magnification function ("linear" produces better results)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); //The minifying function
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECR );
// Finally we define the 2d texture
glTexImage2D(GL_TEXTURE_2D, 0, 4, infoheader.biWidth, infoheader.biHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, l_texture);
// And create 2d mipmaps for the minifying function
gluBuild2DMipmaps(GL_TEXTURE_2D, 4, infoheader.biWidth, infoheader.biHeight, GL_RGBA, GL_UNSIGNED_BYTE, l_texture);
free(l_texture); // Free the memory we used to load the texture
return (num_texture); // Returns the current texture OpenGL ID
}
I call the function in init section
textureID = LoadTexture("Building.bmp",255);
and in the display section I wrote :
glBindTexture(GL_TEXTURE_2D,textureID);
glBegin(GL_QUADS);
//front
glTexCoord2f(1,0) ; glVertex3f(1,-1,0);
glTexCoord2f(1,1) ; glVertex3f(1,1,0);
glTexCoord2f(0,1) ; glVertex3f(-1,1,0);
glTexCoord2f(0,0) ; glVertex3f(-1,-1,0);
glEnd();