OpenGL gaps within sphere

Question

I have recently been trying to render a 3D sphere in OpenGL using triangles. I have been testing and modifying code from various websites and have finally found a winning combination. The only problem is that there are visible gaps in the sphere. Any thoughts on what would be causing this?

Code to render sphere

float Slices = 30;
float Stacks = 60;
float Radius = 20.0;
for (int i = 0; i <= Stacks; ++i){

    float V   = i / (float) Stacks;
    float phi = V * glm::pi <float> ();

    for (int j = 0; j <= Slices; ++j){

        float U = j / (float) Slices;
        float theta = U * (glm::pi <float> () * 4);

        float x = cosf (theta) * sinf (phi);
        float y = cosf (phi);
        float z = sinf (theta) * sinf (phi);
        x *= Radius;
        y *= Radius;
        z *= Radius;

        Vertex *v = new Vertex {{x,y,z},    //Position
                                {255,0,0}}; //Color
        screenToBuffer(v, 1);
        delete []v;
    }
}

Problem enter image description here

The point calculation looks fine. But in addition, you'll need an index array that defines the correct connectivity to create triangles from these points. Either that, or you'll have to repeat points. — Reto Koradi, Dec 09 '14 at 06:44

score -1 · Answer 1 · edited May 23 '17 at 12:12

-1

Try and set it to GL_TRIANGLE_STRIP

What might be the problem is that it considers each group of three vertices to be only one triangle.

Like so

Indices:     0 1 2 3 4 5 ...
Triangles:  {0 1 2} {3 4 5}

The GL_TRIAGLE_STRIP will do this.

 Indices:     0 1 2 3 4 5 ... 
 Triangles:  {0 1 2}
               {1 2 3}  drawing order is (2 1 3) to maintain proper winding
                 {2 3 4}
                   {3 4 5}

See this answer for a proper way to do it. https://stackoverflow.com/a/7958376/1943599

edited May 23 '17 at 12:12

Community

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answered Dec 08 '14 at 23:55

Mellester

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Simply drawing a triangle strip with the points shown in the OP's code would still look about equally wrong. The points are not calculated in an order that would be correct to render a sphere with triangle strips. – Reto Koradi Dec 09 '14 at 06:46
I just assumed he had cull face disabled. – Mellester Dec 09 '14 at 11:15

OpenGL gaps within sphere

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