/*
* If (currentX, currentY) == (desiredX, desiredY), then
* the resulting movement direction is arbitrary.
*/
public static ObjectAction MoveTowardsLocation(
IMathExpression currentX,
IMathExpression currentY,
IMathExpression desiredX,
IMathExpression desiredY,
/*
* Note that movement speed is not affected by shouldSnapshot
*/
IMathExpression movementSpeedInPixelsPerSecond,
/*
* When true, will decide movement direction on the first frame, and keep that direction.
* When false, will continuously move towards (desiredX, desiredY)
*/
bool shouldSnapshot,
GuidGenerator guidGenerator)
{
string deltaXVariable = guidGenerator.NextGuid();
string deltaYVariable = guidGenerator.NextGuid();
ObjectAction setDeltaX = ObjectAction.SetNumericVariable(deltaXVariable, MathExpression.Subtract(desiredX, currentX));
ObjectAction setDeltaY = ObjectAction.SetNumericVariable(deltaYVariable, MathExpression.Subtract(desiredY, currentY));
BooleanExpression areDeltasBothZero = BooleanExpression.And(
BooleanExpression.Equal(MathExpression.Variable(deltaXVariable), MathExpression.Constant(0)),
BooleanExpression.Equal(MathExpression.Variable(deltaYVariable), MathExpression.Constant(0)));
string angleInMillidegreesVariable = guidGenerator.NextGuid();
ObjectAction setAngle = ObjectAction.Union(
shouldSnapshot ? ObjectActionGenerator.DoOnce(setDeltaX) : setDeltaX,
shouldSnapshot ? ObjectActionGenerator.DoOnce(setDeltaY) : setDeltaY,
ObjectAction.Condition(
condition: areDeltasBothZero,
action: ObjectAction.SetNumericVariable(angleInMillidegreesVariable, MathExpression.Constant(0))),
ObjectAction.Condition(
condition: BooleanExpression.Not(areDeltasBothZero),
action: ObjectAction.SetNumericVariable(angleInMillidegreesVariable, MathExpression.ArcTangentScaled(MathExpression.Variable(deltaXVariable), MathExpression.Variable(deltaYVariable), false))),
ObjectAction.SetNumericVariable(angleInMillidegreesVariable, MathExpression.Multiply(MathExpression.Variable(angleInMillidegreesVariable), MathExpression.Constant(-1))),
ObjectAction.SetNumericVariable(angleInMillidegreesVariable, MathExpression.Add(MathExpression.Variable(angleInMillidegreesVariable), 90 * 1000)));
IMathExpression xMillis =
MathExpression.Divide(
MathExpression.Multiply(
movementSpeedInPixelsPerSecond,
MathExpression.ElapsedMillisecondsPerIteration(),
MathExpression.SineScaled(MathExpression.Variable(angleInMillidegreesVariable))),
MathExpression.Constant(1000));
IMathExpression yMillis =
MathExpression.Divide(
MathExpression.Multiply(
movementSpeedInPixelsPerSecond,
MathExpression.ElapsedMillisecondsPerIteration(),
MathExpression.CosineScaled(MathExpression.Variable(angleInMillidegreesVariable))),
MathExpression.Constant(1000));
string xMillisVariable = guidGenerator.NextGuid();
string yMillisVariable = guidGenerator.NextGuid();
ObjectAction setXMillisVariable = shouldSnapshot
? ObjectActionGenerator.DoOnce(ObjectAction.SetNumericVariable(xMillisVariable, xMillis))
: ObjectAction.SetNumericVariable(xMillisVariable, xMillis);
ObjectAction setYMillisVariable = shouldSnapshot
? ObjectActionGenerator.DoOnce(ObjectAction.SetNumericVariable(yMillisVariable, yMillis))
: ObjectAction.SetNumericVariable(yMillisVariable, yMillis);
return(ObjectAction.Union(
setAngle,
setXMillisVariable,
setYMillisVariable,
ObjectAction.SetPosition(
xMillis: MathExpression.Add(MathExpression.XMillis(), MathExpression.Variable(xMillisVariable)),
yMillis: MathExpression.Add(MathExpression.YMillis(), MathExpression.Variable(yMillisVariable)))));
}
