public CircleGeometry(float radius=1,int segments=8,float thetaStart = 0, float thetaLength = Mathf.Tau)
{
segments = Mathf.Max(3, segments);
var uvs = new List<Vector2>();
vertices.Add(Vector3.Zero);
uvs.Add(Vector2.Half);
for(var i = 0f; i <= segments; i ++ )
{
var segment = thetaStart + i / segments * thetaLength;
var v = new Vector3(Mathf.Cos( segment ),radius * Mathf.Sin( segment ),0);
v.Multiply(radius);
vertices.Add(v);
uvs.Add(new Vector2(( v.x / radius + 1 ) / 2, ( v.y / radius + 1 ) / 2 ));
}
var n = Vector3.UnitZ;
for (var i = 1; i <= segments; i++)
{
faces.Add(new Face3(i, i + 1, 0, n));
var faceSet = new UVFaceSet(uvs[i], uvs[i + 1], Vector2.Half);
faceVertexUvs[0].Add(faceSet);
}
ComputeNormals();
BoundingSphere = new Sphere(Vector3.Zero,radius );
}
private void HandleTriangle(int a, int b, int c, int ua, int ub, int uc, UVFaceSet uv, List <Vector3> tan1, List <Vector3> tan2)
{
Vector3 vA = vertices[a], vB = vertices[b], vC = vertices[c];
Vector2 uvA = uv[ua], uvB = uv[ub], uvC = uv[uc];
var x1 = vB.x - vA.x;
var x2 = vC.x - vA.x;
var y1 = vB.y - vA.y;
var y2 = vC.y - vA.y;
var z1 = vB.z - vA.z;
var z2 = vC.z - vA.z;
var s1 = uvB.x - uvA.x;
var s2 = uvC.x - uvA.x;
var t1 = uvB.y - uvA.y;
var t2 = uvC.y - uvA.y;
var r = 1 / (s1 * t2 - s2 * t1);
var sdir = new Vector3((t2 * x1 - t1 * x2) * r, (t2 * y1 - t1 * y2) * r, (t2 * z1 - t1 * z2) * r);
var tdir = new Vector3((s1 * x2 - s2 * x1) * r, (s1 * y2 - s2 * y1) * r, (s1 * z2 - s2 * z1) * r);
var tA1 = tan1[a];
tA1.Add(sdir);
tan1[a] = tA1;
var tB1 = tan1[b];
tB1.Add(sdir);
tan1[b] = tB1;
var tC1 = tan1[c];
tC1.Add(sdir);
tan1[c] = tC1;
var tA2 = tan2[a];
tA2.Add(tdir);
tan2[a] = tA2;
var tB2 = tan2[b];
tB2.Add(tdir);
tan2[b] = tB2;
var tC2 = tan2[c];
tC2.Add(tdir);
tan2[c] = tC2;
}
private void HandleTriangle(int a, int b, int c, int ua, int ub, int uc, UVFaceSet uv, List<Vector3> tan1, List<Vector3> tan2)
{
Vector3 vA = vertices[a], vB = vertices[b], vC = vertices[c];
Vector2 uvA = uv[ua], uvB = uv[ub], uvC = uv[uc];
var x1 = vB.x - vA.x;
var x2 = vC.x - vA.x;
var y1 = vB.y - vA.y;
var y2 = vC.y - vA.y;
var z1 = vB.z - vA.z;
var z2 = vC.z - vA.z;
var s1 = uvB.x - uvA.x;
var s2 = uvC.x - uvA.x;
var t1 = uvB.y - uvA.y;
var t2 = uvC.y - uvA.y;
var r = 1 / (s1 * t2 - s2 * t1);
var sdir = new Vector3((t2 * x1 - t1 * x2) * r, (t2 * y1 - t1 * y2) * r, (t2 * z1 - t1 * z2) * r);
var tdir = new Vector3((s1 * x2 - s2 * x1) * r, (s1 * y2 - s2 * y1) * r, (s1 * z2 - s2 * z1) * r);
var tA1 = tan1[a];
tA1.Add(sdir);
tan1[a] = tA1;
var tB1 = tan1[b];
tB1.Add(sdir);
tan1[b] = tB1;
var tC1 = tan1[c];
tC1.Add(sdir);
tan1[c] = tC1;
var tA2 = tan2[a];
tA2.Add(tdir);
tan2[a] = tA2;
var tB2 = tan2[b];
tB2.Add(tdir);
tan2[b] = tB2;
var tC2 = tan2[c];
tC2.Add(tdir);
tan2[c] = tC2;
}
// Approximate a curved face with recursively sub-divided triangles.
private void Make(VertexInfo v1, VertexInfo v2, VertexInfo v3)
{
var face = new Face3(v1.Index, v2.Index, v3.Index, v1.Position, v2.Position, v3.Position);
faces.Add(face);
var centroid = v1.Position;
centroid.Add(v2.Position);
centroid.Add(v3.Position);
centroid.Divide(3);
var azi = Azimuth(centroid);
var uvA = CorrectUV(v1.UV, v1.Position, azi);
var uvB = CorrectUV(v2.UV, v2.Position, azi);
var uvC = CorrectUV(v3.UV, v3.Position, azi);
var faceSet = new UVFaceSet(uvA,uvB,uvC);
var uvs = faceVertexUvs[0];
uvs.Add(faceSet);
}