private GeometricObject init_drawing()
{
idx_uc3dBuffer = 0;
if (gobj_drawing != null && !gobj_drawing.initialized)
{
gobj_drawing.Begin();
}
return(gobj_drawing);
}
void Sphere(GeometricObject obj)
{
var fcl = new Color(0.5f, 0.5f, 0.5f, 1.0f);
var stacks = 20;
var slices = 2 * stacks;
var radius = 1.0f;
obj.Begin();
obj.SetSphereStacks(stacks);
obj.SetSphereSlices(slices);
obj.SetSphereRadius(radius);
obj.SetSphereFrontColor(fcl);
obj.AddSphere(Vector3.zero);
obj.End();
}
// see https://en.wikipedia.org/wiki/Enneper_surface
void Enneper(GeometricObject obj)
{
System.Func <int, int, Vector3> f = (r, c) => {
var o = new Vector3();
var u = (float)r / 10f;
var v = (float)c / 10f;
o.x = u * (1f - u * u + v * v) / 3f;
o.y = v * (1f - v * v + u * u) / 3f;
o.z = (u * u - v * v) / 3f;
return(o * 0.5f);
};
var alpha = 1.0f;
var pcl = new Color(1.0f, 1.0f, 1.0f, alpha);
var fcl = new Color(0.5f, 0.5f, 1.0f, alpha);
var bcl = new Color(0.5f, 0.5f, 0.0f, alpha);
var rows = 51;
var cols = 51;
var idxs = new int[rows, cols];
var points = new List <Vector3> ();
points.Clear();
for (var r = -rows / 2; r <= rows / 2; r++)
{
for (var c = -cols / 2; c <= cols / 2; c++)
{
idxs [rows / 2 + r, cols / 2 + c] = points.Count;
points.Add(f(r, c));
}
}
obj.Begin();
obj.SetPointFrontColor(pcl);
for (var r = 0; r < rows; r++)
{
for (var c = 0; c < cols; c++)
{
obj.AddPoint(points [idxs[r, c]]);
}
}
obj.SetMeshFrontColor(fcl);
obj.SetMeshBackColor(bcl);
obj.AddMesh(rows, cols, points, idxs);
obj.End();
}
// see https://en.wikipedia.org/wiki/Torus_knot
void TorusKnot(GeometricObject obj)
{
System.Func <float, Vector3> f = (phi) => {
var o = new Vector3();
var p = 3f;
var q = 8f;
var r = Mathf.Cos(q * phi) + 2f;
o.x = r * Mathf.Sin(p * phi);
o.y = r * Mathf.Cos(p * phi);
o.z = -Mathf.Sin(q * phi);
return(o);
};
var alpha = 1.0f;
var n = 1200;
var frontColors = new List <Color32> ();
var points = new List <Vector3> ();
frontColors.Clear();
for (var i = 0; i < n; ++i)
{
var hue = (float)i / n;
var cl = Color.HSVToRGB(hue, 1f, 1f);
cl.a = alpha;
frontColors.Add(cl);
}
points.Clear();
for (var i = 0; i < n; ++i)
{
var w = 2f * Mathf.PI * (float)i / n;
points.Add(f(w));
}
obj.Begin();
obj.SetLineRadius(0.3f);
obj.SetLineTopology(Pen.Topology.Close);
obj.AddLine(points, frontColors);
obj.End();
}