Question

I have a problem with lightning. Lightning works on:

//...
gluSphere(qobj, r1, precision, precision);
//...

But it dosnt work on:

//...
glBegin(GL_TRIANGLES);
glColor3fv(colors[4]);
glVertex3fv(vertices[triangles[fig2][1]]);
glVertex3fv(vertices[triangles[fig2][2]]);
glVertex3fv(vertices[triangles[fig2][3]]);
glEnd();
//...

Here is how it looks:

img http://img72.imageshack.us/img72/2158/36156234.jpg

As you can see only “gluSphere” is lightened. How to make same lightning on GL_TRIANGLES and GL_POLYGON?

Answer 1

A lighting engine needs to know which direction a polygon is facing. Instead of calculating those by itself, OpenGL requires you to provide this information through normals:

//...
glBegin(GL_TRIANGLES);
glColor3fv(colors[4]);
// put a call to glNormal3fv or glNormal3f here!
glVertex3fv(vertices[triangles[fig2][1]]);
glVertex3fv(vertices[triangles[fig2][2]]);
glVertex3fv(vertices[triangles[fig2][3]]);
glEnd();
//...