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opengllightopengl-compat

how set light and materials to obtain an emerald object

When I set the material in opengl for an object (glutSolidSphere(2.,10.,8.);), let for example the emerald parameters:

 float[] mat_ambient ={ 0.0215f, 0.1745f, 0.0215f, 0.55f };
 float[] mat_diffuse ={0.07568f, 0.61424f, 0.07568f, 0.55f };
 float[] mat_specular ={0.633f, 0.727811f, 0.633f, 0.55f };
 float shine = 76.8f;

In order to obtain really an emerald object I should set the components of light in the same way? I mean:

float[] light_ambient ={ 0.0215f, 0.1745f, 0.0215f, 0.55f };
float[] light_diffuse ={0.07568f, 0.61424f, 0.07568f, 0.55f };
float[] light_specular ={0.633f, 0.727811f, 0.633f, 0.55f };

float[] light_position= { 1.0, 1.0, 1.0, 0.0 };

The result is not good...

Solution

  • If you want to render a green surface with a Blinn–Phong reflection model and Gouraud shading you have found the answer. However, you can't do anything more realistic with the 20-year-old OpenGL Fixed-Function pipeline. Same reason as in the comments on your previous question How can I do a brass surface?.
    With Gouraud shading the ligh model is computed per vertex, compared to Phong shadding where it is computed per fragment. Use a higher resolution on the sphere to improve lighting and get some specular highlights. See GLSL fixed function fragment program replacement and What's the difference between Phong shading and Gouraud shading?.