varying vec3 diffuseColor;
    // the interpolated diffuse Phong lighting
varying vec3 specularColor;
    // the interpolated specular Phong lighting
varying vec4 texCoords;
    // the interpolated texture coordinates
uniform sampler2D mytexture;

void main(void)
{
    vec2 longitudeLatitude = vec2((atan(texCoords.y, texCoords.x) / 3.1415926 + 1.0) * 0.5,
                                  (asin(texCoords.z) / 3.1415926 + 0.5));
    // unusual processing of texture coordinates

    gl_FragColor = vec4(diffuseColor
        * vec3(texture2D(mytexture, longitudeLatitude))
        + specularColor, 1.0);
}