   Slowness with background texture
  Hello,I use glOrtho() to blit a texture as scene background with 2D coords. When I use a 256x256 texture, everything goes fine. But when I use a texture of 640x480, it is very very slow - I draw a rotating cube to see it. It goes to 1 ~frame/sec... Is there something I must do when loading the texture to avoid this problem? Or maybe it is somewhere else...// Here is how I set 2Dvoid TDE::Start2D(void){   glViewport(0, 0, width, height);   glMatrixMode(GL_PROJECTION);   glLoadIdentity();   glOrtho(0, width, height, 0, 1, -1);   glMatrixMode(GL_MODELVIEW);   glLoadIdentity();}// Here is how I blit the texturevoid TDE_TEXTURE::Blit(int x, int y, int w, int h){   GLfloat x2, y2;   if (texture == 0xdeadbeef) return;   x2 = x + w;   y2 = y + h;   glEnable(GL_TEXTURE_2D);   glBindTexture(GL_TEXTURE_2D, texture);   glBegin(GL_QUADS); glTexCoord2f(0, 0); glVertex3f(x,   y, 0); glTexCoord2f(1, 0); glVertex3f(x2,  y, 0); glTexCoord2f(1, 1); glVertex3f(x2, y2, 0); glTexCoord2f(0, 1); glVertex3f(x,  y2, 0);   glEnd();}Thanks in advance...   
  It can be caused by the non-power-of-2 textureYou must use an extension that allows you that or stick to texture with power of 2   ;  Im pretty n00bish at this, but doesnt ortho mode create a mask, rather than a background?   ;  @PermanubWhat do you mean with mask or background?In ortho mode you can use your z-coord as well for depth, to define what is in front and what behind. So you can create the background   ;  try disabling blending and lighting before you draw.  those are the usual suspects (glDisable with  GL_BLEND, and GL_LIGHTING).  other things that don't make sense: fog, and depth test.   ;  I'm also voting for the non-power-of-2 texture being the problem. Check out the texture rectangle extension... here.   