read pixels from back buffer
I want to read the pixels from the back buffer. But all i get so far is a black screen (the clear color).
The thing is, is that i don't need a glut window to draw to. Once i have the pixel information, then i pass that to another program which will draw the image for me.
My init function looks like this:
Code:
char fakeParam[] = "nothing";
char *fakeargv[] = { fakeParam, NULL };
int fakeargc = 1;
glutInit( &fakeargc, fakeargv );
GLenum err = glewInit();
if (GLEW_OK != err)
{
MessageBoxA(NULL, "Failed to initialize OpenGL", "ERROR", NULL);
}
else
{
glEnable(GL_TEXTURE_2D);
glEnable(GL_DEPTH_TEST);
// Not sure if this call is needed when i don't use a glut window to render too...
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
}
Then in my render function i do:
Code:
void DisplayFunc(void)
{
static float alpha = 0;
/* Clear the buffer, clear the matrix */
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
// TEAPOT
glTranslatef(0.0f, 0.0f, -5.0f); // Translate back 5 units
glRotatef(rotation_degree, 1.0f, 1.0f, 0.0f); // Rotate according to our rotation_degree value
glFrontFace(GL_CW);
glutSolidTeapot(1.0f); // Render a teapot
glFrontFace(GL_CCW);
glReadBuffer(GL_BACK);
glReadPixels(0, 0, (GLsizei)1024, (GLsizei)768, GL_RGB, GL_UNSIGNED_BYTE, pixels);
}
This is basically all i do. At the end of the last function is where i'm trying to read all the pixels. But the output is just a black image.
Anyone any idea what i'm doing wrong...??