/// <summary>
/// use this to round to a percent (0 to 100)
/// </summary>
public static double RoundNumber(double num)
{
int dec = 2;
double result = 100 * JsMath.Round(num * JsMath.Pow(10, dec)) / JsMath.Pow(10, dec);
return(result);
}
//the following function handles the "physics" of how the can moves
//calculating roation of the can and the direction of movement etc.
//can be ignored if you only care about how to grab accelerometer readings
//and do animations.
// //the can wants to slide in the direction of the slope of the table.
// //and wants to rotate such that the can is perpendicular to that direction (has reciprocal slope)
// //the label of the can want to rotate in the direction opposite to gravity.
public static void DoCanPhysics(XdkAcceleration a)
{
x_ispos = 1;
y_ispos = 1;
//take the abs tilt values so we don't
//get stupid results while doing interim
//calculations
absx = JsMath.Abs(a.x);
absy = JsMath.Abs(a.y);
if (absx < .1)
{
absx = 0;
}
if (absy < .1)
{
absy = 0;
}
//skip the calculations if there is no movement;
if (absx == absy && absx == 0)
{
return;
}
//var opp;
//var adj;
//what is the angle of the vector of motion of the can?
//first calc without regard to sign of the accelerometer vectors
lastangle = vectangle;
vectangle = JsMath.Round(JsMath.Atan2(a.y, a.x) * 180 / JsMath.PI);
// //ignore small variations in rotation so that the can doesn't shake incessantly
// if (lastangle > vectangle) {
// if (Math.abs(lastangle - vectangle) < 10) {
// vectangle = lastangle;
// }
// }
// else {
// if (Math.abs(vectangle - lastangle) < 10) {
// vectangle = lastangle;
// }
// }
//now, adjust the arctan calculation for direction of the accel vectors
//by adding the correct angle based on the quatrant
// that the motion occurs in.
//quadrant 1
if (x_ispos > 0 && y_ispos > 0)
{
vectangle = 90 - vectangle;
}
//quadrant 2
else if (x_ispos > 0 && y_ispos < 0)
{
vectangle = 90 + vectangle;
}
//quadrant 3
else if (x_ispos < 0 && y_ispos < 0)
{
vectangle = 270 - vectangle;
}
//quadrant 4
else if (x_ispos < 0 && y_ispos > 0)
{
vectangle = 270 + vectangle;
}
//make the motion vect angle positive.
if (vectangle < 0)
{
vectangle = (vectangle + 360) % 360;
}
//allow some accelerated movement based on how tilted the device is
dx = JsMath.Floor(JsMath.Log(RoundNumber(absx) * 5));
dx = JsMath.Max(dx, 0);
dy = JsMath.Floor(JsMath.Log(RoundNumber(absy) * 5));
dy = JsMath.Max(dy, 0);
x_ispos = 1;
y_ispos = 1;
if (a.x < 0)
{
x_ispos = -1;
}
if (a.y < 0)
{
y_ispos = -1;
}
//now put back the sign
dx = dx * x_ispos;
dy = dy * y_ispos;
//calculate can movements
current_left += dx;
current_top -= dy;
canangle = (canangle + 360) % 360;
double a1, a2, a3, a4, af;
//a1 and a2 then can is within 90
//a3 and a4 can is upside down relative to
//the motion vector
labeldirection = 1;
a1 = vectangle + 90 - canangle;
//HtmlElement.GetById("accel_z").innerHTML = "case 1: " ;
af = a1;
a2 = vectangle - 90 - canangle;
if (JsMath.Abs(a2) < JsMath.Abs(af))
{
af = a2;
// HtmlElement.GetById("accel_z").innerHTML = "case 2: ";
}
a3 = vectangle + 90 - canangle + 180;
if (JsMath.Abs(a3) < JsMath.Abs(af))
{
af = a3;
//HtmlElement.GetById("accel_z").innerHTML = "case 3: ";
labeldirection = -1;
}
a4 = vectangle - 90 - canangle + 180;
if (JsMath.Abs(a4) < JsMath.Abs(af))
{
af = a4;
// HtmlElement.GetById("accel_z").innerHTML = "case 4: a4 = " + a4 + "a3 = " + a3 + "a2 = " + a2 + "a1 = " + a1;
labeldirection = -1;
}
if (af > 180)
{
af = -1 * (360 - af);
}
//HtmlElement.GetById("accel_y").innerHTML = "vectangle= " + vectangle + "; canangle=" + canangle + " rotpos=" + af; // + "; rotneg=" + rotneg + "; nextrot=" + nextrot;
// HtmlElement.GetById("accel_x").innerHTML = "a.x = " + a.x + ", a.y = " + a.y;
//which way should the label spin?
//it should spin right when moving at 90deg to the
//motion vector, spin left when moving at 270deg
if (canangle > vectangle)
{
labeldirection = -1;
}
if (JsMath.Abs(canangle - vectangle) > 180)
{
labeldirection = labeldirection * -1;
}
//if the movement is right or down then the label and can is upright, label move left
labelleft += labeldirection * JsMath.Ceil(JsMath.Sqrt(dx * dx + dy * dy));
if (af > 3)
{
canangle++;
}
else if (af < -3)
{
canangle--;
}
}