/// <summary>
/// Rotates by the specified angle in Radians
/// </summary>
public void RotateBy(float angle)
{
float sin = NumberUtil.FastSin(angle);
float cos = NumberUtil.FastCos(angle);
X = X * cos - Y * sin;
Y = X * sin + Y * cos;
}
/// <summary>
/// Applies a rotation on the matrix (angle in radians).
/// </summary>
public void Rotate(float angleInRadians)
{
if (angleInRadians == 0.0f)
{
return;
}
float sin = NumberUtil.FastSin(angleInRadians);
float cos = NumberUtil.FastCos(angleInRadians);
float a = A * cos - B * sin;
float b = A * sin + B * cos;
float c = C * cos - D * sin;
float d = C * sin + D * cos;
float tx = Tx * cos - Ty * sin;
float ty = Tx * sin + Ty * cos;
A = a;
B = b;
C = c;
D = d;
Tx = tx;
Ty = ty;
}
public string TestLUTAccuracy()
{
float angle = -1000;
int numIter = (int)Math.Abs(angle) * 200;
float angleDiff = Math.Abs(angle) * 2 / numIter;
double biggestError = 0;
for (int i = 0; i < numIter; i++)
{
angle += angleDiff;
var sinDiff = Math.Abs(Math.Abs(Math.Sin(angle)) - Math.Abs(NumberUtil.FastSin(angle)));
var cosDiff = Math.Abs(Math.Abs(Math.Cos(angle)) - Math.Abs(NumberUtil.FastCos(angle)));
if (sinDiff > biggestError)
{
biggestError = sinDiff;
}
if (cosDiff > biggestError)
{
biggestError = sinDiff;
}
}
return("largest error: " + biggestError); // around 0.0045
}
public string TestSinCosSpeed()
{
const int NUMTRIES = 1000000;
float angle = 0.0f;
float ret0 = 0;
Stopwatch watch = new Stopwatch();
watch.Restart();
for (int i = 0; i < NUMTRIES; i++)
{
angle += 0.01f;
ret0 = NumberUtil.FastSin(angle);
}
var res0 = watch.ElapsedMilliseconds;
float ret1 = 0;
watch = new Stopwatch();
watch.Restart();
for (int i = 0; i < NUMTRIES; i++)
{
angle += 0.01f;
ret1 = NumberUtil.SinLUT[(int)(angle * 159.154943092f + 0.5f) & 1000];
}
var res1 = watch.ElapsedMilliseconds;
float ret2 = 0.0f;
angle = 0;
watch = new Stopwatch();
watch.Restart();
for (int i = 0; i < NUMTRIES; i++)
{
angle += 0.01f;
ret2 = (float)Math.Sin(angle);
}
var res2 = watch.ElapsedMilliseconds;
float ret3 = 0.0f;
angle = 0;
watch = new Stopwatch();
watch.Restart();
for (int i = 0; i < NUMTRIES; i++)
{
angle += 0.01f;
//always wrap input angle to -PI..PI
if (angle < -3.14159265f)
{
angle += 6.28318531f;
}
else if (angle > 3.14159265f)
{
angle -= 6.28318531f;
}
//compute sine
if (angle < 0.0f)
{
ret3 = 1.27323954f * angle + .405284735f * angle * angle;
}
else
{
ret3 = 1.27323954f * angle - 0.405284735f * angle * angle;
}
}
var res3 = watch.ElapsedMilliseconds;
return("LUT func call: " + res0 + " LUT inline: " + res1 + " Math.Sin: " + res2 + " fastcalc: " + res3);
}
