Question

I am new to OpenGL programming.I have made a rotating cube with different images on different faces of the cube..i want to set background for the Screen..Any help will be appreciated..

Answer 1

Draw a textured quad covering the whole viewport. To do this, switch the projection and modelview to identity and disable depth testing. With projection and modelview being identity vertex coordinates [-1 … 1] will cover the whole viewport. In code:

glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

GLfloat tex_quad[16] = {
/* x, y, s, t */
-1, -1, 0, 0,
 1, -1, 1, 0,
 1,  1, 1, 1,
-1,  1, 0, 1
};    

glVertexPointer(2, GL_FLOAT, sizeof(GLfloat)*4, &tex_quad[0]);
glTexCoordPointer(2, GL_FLOAT, sizeof(GLfloat)*4, &tex_quad[2]);

glDisable(GL_DEPTH_TEST);
glDepthMask(GL_FALSE);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, background_image_texture_ID);

glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

glEnable(GL_DEPTH_TEST);
glDepthMask(GL_TRUE);
glDisable(GL_TEXTURE_2D);