Im trying to implement basic lighting in Opengl 3+ (a sun) with this tutorial :


Im building a basic terrain and its working well. Now im trying to add normals, and I think its not working well :


Terrain in wireframe

As you can see I dont think my normals are good.

This is how I get them :

for(x = 0; x < this.m_size.width - 1 ; x++)
        for(y = 0; y < this.m_size.height - 1 ; y++)
            immutable uint indice1 = y * this.m_size.width + x;
            immutable uint indice2 = y * this.m_size.width + (x + 1);
            immutable uint indice3 = (y + 1) * this.m_size.width + x;
            immutable uint indice4 = (y + 1) * this.m_size.width + x;
            immutable uint indice5 = y * this.m_size.width + (x + 1);
            immutable uint indice6 = (y + 1) * this.m_size.width + (x + 1);

            Vector3 v1 = vertexes[indice3] - vertexes[indice1];
            Vector3 v2 = vertexes[indice2] - vertexes[indice1];
            Vector3 normal = v1.cross(v2);

            normals[indice1] = normal;

            indices ~= [indice1,

I use this basic shader : http://ogldev.atspace.co.uk/www/tutorial18/tutorial18.html or in the link I posted at the top.



By looking at your picture your problem seems that you need to smooth(average) your normals. That is when a vertex is shared by multiple triangles and yet has one normal you have two options to deal with this problem:

  • Smooth edges: You calculate the normal of each vertex for each adjacent triangle and then average them.
  • Hard edges: You duplicate each vertex, especially at the edges where the normal greatly varies between triangles. It practically has 3 different normals (though it's not actually) but then you have the effect of hard edges.

I provided the full code for smooth normals here. And more detailed explanation for this issue here.

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  • 1
    \$\begingroup\$ Very nice. You solved my problem. I think it's better now : i.imgur.com/4RRaDx0.png \$\endgroup\$ – Aldo Jan 13 '14 at 19:08

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