/* * 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))))); }