GlGenTextures keeps returing 0's - c++

Question

I'm trying to generate textures like so:
#define checkImageWidth 64
#define checkImageHeight 64
static GLubyte checkImage[checkImageHeight][checkImageWidth][4];
static GLubyte otherImage[checkImageHeight][checkImageWidth][4];
static GLuint texName[2];
void makeCheckImages(void)
{
int i, j, c;
for (i = 0; i < checkImageHeight; i++) {
for (j = 0; j < checkImageWidth; j++) {
c = ((((i&0x8)==0)^((j&0x8))==0))*255;
checkImage[i][j][0] = (GLubyte) c;
checkImage[i][j][1] = (GLubyte) c;
checkImage[i][j][2] = (GLubyte) c;
checkImage[i][j][3] = (GLubyte) 255;
c = ((((i&0x10)==0)^((j&0x10))==0))*255;
otherImage[i][j][0] = (GLubyte) c;
otherImage[i][j][1] = (GLubyte) 0;
otherImage[i][j][2] = (GLubyte) 0;
otherImage[i][j][3] = (GLubyte) 255;
}
}
}
void init(void)
{
glClearColor (1.0, 0.0, 0.0, 0.0);
glShadeModel(GL_FLAT);
glEnable(GL_DEPTH_TEST);
makeCheckImages();
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glGenTextures(2, texName);
glBindTexture(GL_TEXTURE_2D, texName[0]);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,
GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, checkImageWidth,
checkImageHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE,
checkImage);
glBindTexture(GL_TEXTURE_2D, texName[1]);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,
GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
GL_NEAREST);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, checkImageWidth,
checkImageHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE,
otherImage);
glEnable(GL_TEXTURE_2D);
engineGL.current.tex = texName[1];
}
But when I check the values of texName[0] and [1] they are both 0, I do not understand why, what am I doing wrong. Thanks.

Answer 1

You probably are calling glGenTextures before creating the OpenGL context, and that will generate a GL error. Don't try to create textures before you've initialized OpenGL.

Answer 2

I had this problem, and glGetError() was returning 0.
In my case it was caused by calling glGenTextures(...) on a different thread to the one the GL context was created on (because I was loading the textures asynchronously). Calling it from the main thread after the async load made glGenTextures(...) start working again.

Answer 3

Try calling glGetError. It should tell you in more detail what went wrong. In general, if an OpenGL function fails, the first thing you do should be to ask OpenGL why it failed. It knows, because it just tried to execute the function.
It's much harder for us to guess at what might have gone wrong.

Answer 4

In my case, I was "lazy loading" my texture, so the glGenTexture was inside a glBegin / glEnd command !

Answer 5

before calling glGenTexture, your opengl context must be created and XXXMakeCurrent'ed