I rendered a cube with quads in the usual way:
glBegin(…);
glNormal(…);
glVertex(…);
glNormal(…);
glVertex(…);
…
glEnd();
Then I put a light and faces of the cube seems to be lighted by separate triangles and they arent shaded correctly since faces have the diagonals brighter than the face itself. Is this usual??
When I put one normal per face I think it was correctly shaded, but this problem come when individual vertexes get involved, since the same thing happens if I dont do lighting but apply different colors to each vertex.