CODEWITHSUNDEEP
c++copengllegacy
user4085386
user4085386

Reputation:

How to enable both side lighting for GL_POINTS with vertex normals

How to enable both side lighting for GL_POINTS in opengl? It seems glLightModeli(GL_LIGHT_MODEL_TWO_SIDE, GL_TRUE); is working for only facets, but not GL_POINTS.

What I am doing is supplying both vertices and the vertex normals with lighting enabled. With GL_LIGHT_MODEL_TWO_SIDE disabled, GL_POINTS are lit according to the normal direction. But I cannot enable both sided lighting for GL_POINTS.

Can this be done using OpenGL legacy functions? Or would I have to render both sides by negating all the normals?

Thanks in advance. Please do not comment to use modern OpenGL as that is not the answer to my question, but only a suggestion.

Upvotes: 1

Views: 928

Answers (1)

Nicol Bolas
Nicol Bolas

Reputation: 473537

How to enable both side lighting for GL_POINTS in opengl?

You don't. Points and lines do not have sides. Only face primitives (triangles, quads, etc) have sides.

So if you want the lighting computation to reverse the normal if the normal is facing away or something, then yes, you will have to render your geometry twice.

Upvotes: 2

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