Gouraud shading is independent of vertex normals. Except if you have lighting enabled in which case it is only indirectly dependent on the vertex normals. What you get from Gourard shading is a simple pseudo surface smoothing effect, and a better appearance overall.
ie, colours are computed at each vertex and interpolated (blended) across the surface. These colours can be specified with glColor*() or if lighting is enabled, these colours are computed using the lighting equations. Here the vertex normals are used to calculate the colour (and other stuff like lighting properties, material properties etc).
Gouraud shading falls down if the polygon is very large and a light patch should appear in the center. This is because only lighting at the vertices is calculated. Phong shading is the next step up, but takes a lot longer to calculate. If you get this problem, subdivide your polygons.
Gouraud shading falls down if the polygon is very large and a light patch should appear in the center. This is because only lighting at the vertices is calculated. Phong shading is the next step up, but takes a lot longer to calculate. If you get this problem, subdivide your polygons.
I have a similar problem.
I have a big wall and I want to light this in
the center.
How subdivide the wall?