// TODO: move to math lib
private Vector2 PolarTolinear(Polar2 p)
{
var r = p.R;
var a = p.A;
a = MathHelper.ToRadians(((a + 360) % 360));
var x = (float)Math.Cos(a) * r;
var y = -(float)Math.Sin(a) * r;
return(new Vector2(x, y));
}
/// <param name="n">Number of teeth</param>
/// <param name="d">Pitch diameter</param>
/// <param name="p">Diametrical pitch</param>
/// <param name="pa">Pressure angle (in degrees)</param>
/// <param name="I">internal</param>
public Gear(GraphicsDevice device, Vector2 position, int n, float d, float p, float pa, bool I = false)
{
// TODO: give everything a sensible name
// TODO: do we need so many points, identify imporant points and remove others
var outerDiameter = (n + (I ? 2.3f : 2.0f)) / p;
var innerDiameter = (n - (I ? 2 : 2.3f)) / p;
var bc = (float)(d * Math.Cos(pa * Math.PI / 180.0));
var radiusMin = innerDiameter / 2;
var radiusMax = outerDiameter / 2;
var rbase = bc / 2;
var ac = 0.0f;
var step = 0.1f;
var first = true;
var fix = 0;
var polarPoints = new List <Polar2>();
polarPoints.Add(new Polar2(radiusMin, 0));
// All hard to follow since its in polar coordinates, TODO: describe better!
// Create a single side of a single tooth, it is nicely curved
/*
* \
* \
* |
* /
*/
for (var i = 1.0f; i < 100.0f; i += step)
{
var bpl = this.PolarTolinear(new Polar2(rbase, -i));
var len = rbase * MathHelper.Pi * 2 / 360.0f * i;
var opl = this.PolarTolinear(new Polar2(len, -i + 90));
var np = this.LinearToPolar(new Vector2(bpl.X + opl.X, bpl.Y + opl.Y));
if (np.R >= radiusMin)
{
if (first)
{
first = false;
step = (2 / (float)n) * 10;
}
if (np.R < d / 2)
{
ac = np.A;
}
if (np.R > radiusMax)
{
if (++fix < 10)
{
i -= step;
step /= 2;
continue;
}
np.R = radiusMax;
polarPoints.Add(np);
break;
}
polarPoints.Add(np);
}
}
// Mirror the side and connect the two via along the top
/*
* /---\
* / \
* | |
* \ /
*/
var fa = 360 / (float)n;
var ma = (fa / 2) + (2 * ac);
var fpa = (fa - ma) > 0 ? 0 : -(fa - ma) / 2;
var m = polarPoints.Count;
polarPoints[0] = new Polar2(radiusMin, fpa);
// Is this part ever called?
while (polarPoints[m - 1].A > ma / 2.0f)
{
Splice(polarPoints, m - 1, 1);
m--;
}
for (var i = polarPoints.Count - 1; i >= 0; i--)
{
var bp = polarPoints[i];
var na = ma - bp.A;
polarPoints.Add(new Polar2(bp.R, na));
}
// Copy and paste these teeth equal along the entire gear
// we now have a full gear, in polar coordinates
m = polarPoints.Count;
for (var i = 1; i < n; i++)
{
for (var pi = 0; pi < m; pi++)
{
var bp = polarPoints[pi];
var na = bp.A + fa * i;
polarPoints.Add(new Polar2(bp.R, na));
}
}
// Convert back from polar to linear coordinates
this.Points = new List <Vector2>();
for (var i = 0; i < polarPoints.Count; i++)
{
var point = this.PolarTolinear(polarPoints[i]);
var x = point.X;
var y = point.Y;
this.Points.Add(new Vector2(x, y));
}
this.Device = device;
this.Position = position;
this.N = n;
// TODO: We're somehow mirroring something here which is why we need the weird minus in the ComputeRotation function
this.Lines = new List <Line>();
for (var i = 1; i < this.Points.Count; i++)
{
var prev = this.Points[i - 1];
var curr = this.Points[i - 0];
var line = new Line(device, Color.Yellow, prev, curr);
line.Position = new Vector3(position.X, 0, position.Y);
line.Update();
this.Lines.Add(line);
}
var p0 = this.Points[this.Points.Count - 1];
var p1 = this.Points[0];
var closingLine = new Line(device, Color.Yellow, p0, p1);
closingLine.Position = new Vector3(position.X, 0, position.Y);
closingLine.Update();
this.Lines.Add(closingLine);
this.Rsc = d * 1.0f / 2;
this.baseAngle = ac;
}