/* Solve coeff(t) == 0, returning the number of roots that
lie withing 0 < t < 1.
coeff[0]t^3 + coeff[1]t^2 + coeff[2]t + coeff[3]
Eliminates repeated roots (so that all tValues are distinct, and are always
in increasing order.
*/
static int solve_cubic_poly(const SkScalar coeff[4], SkScalar tValues[3]) {
if (SkScalarNearlyZero(coeff[0])) { // we're just a quadratic
return SkFindUnitQuadRoots(coeff[1], coeff[2], coeff[3], tValues);
}
SkScalar a, b, c, Q, R;
{
SkASSERT(coeff[0] != 0);
SkScalar inva = SkScalarInvert(coeff[0]);
a = coeff[1] * inva;
b = coeff[2] * inva;
c = coeff[3] * inva;
}
Q = (a*a - b*3) / 9;
R = (2*a*a*a - 9*a*b + 27*c) / 54;
SkScalar Q3 = Q * Q * Q;
SkScalar R2MinusQ3 = R * R - Q3;
SkScalar adiv3 = a / 3;
SkScalar* roots = tValues;
SkScalar r;
if (R2MinusQ3 < 0) { // we have 3 real roots
SkScalar theta = SkScalarACos(R / SkScalarSqrt(Q3));
SkScalar neg2RootQ = -2 * SkScalarSqrt(Q);
r = neg2RootQ * SkScalarCos(theta/3) - adiv3;
if (is_unit_interval(r)) {
*roots++ = r;
}
r = neg2RootQ * SkScalarCos((theta + 2*SK_ScalarPI)/3) - adiv3;
if (is_unit_interval(r)) {
*roots++ = r;
}
r = neg2RootQ * SkScalarCos((theta - 2*SK_ScalarPI)/3) - adiv3;
if (is_unit_interval(r)) {
*roots++ = r;
}
SkDEBUGCODE(test_collaps_duplicates();)
void SkDisplayMath::executeFunction(SkDisplayable* target, int index,
SkTDArray<SkScriptValue>& parameters, SkDisplayTypes type,
SkScriptValue* scriptValue) {
if (scriptValue == NULL)
return;
SkASSERT(target == this);
SkScriptValue* array = parameters.begin();
SkScriptValue* end = parameters.end();
SkScalar input = parameters[0].fOperand.fScalar;
SkScalar scalarResult;
switch (index) {
case SK_FUNCTION(abs):
scalarResult = SkScalarAbs(input);
break;
case SK_FUNCTION(acos):
scalarResult = SkScalarACos(input);
break;
case SK_FUNCTION(asin):
scalarResult = SkScalarASin(input);
break;
case SK_FUNCTION(atan):
scalarResult = SkScalarATan2(input, SK_Scalar1);
break;
case SK_FUNCTION(atan2):
scalarResult = SkScalarATan2(input, parameters[1].fOperand.fScalar);
break;
case SK_FUNCTION(ceil):
scalarResult = SkIntToScalar(SkScalarCeil(input));
break;
case SK_FUNCTION(cos):
scalarResult = SkScalarCos(input);
break;
case SK_FUNCTION(exp):
scalarResult = SkScalarExp(input);
break;
case SK_FUNCTION(floor):
scalarResult = SkIntToScalar(SkScalarFloor(input));
break;
case SK_FUNCTION(log):
scalarResult = SkScalarLog(input);
break;
case SK_FUNCTION(max):
scalarResult = -SK_ScalarMax;
while (array < end) {
scalarResult = SkMaxScalar(scalarResult, array->fOperand.fScalar);
array++;
}
break;
case SK_FUNCTION(min):
scalarResult = SK_ScalarMax;
while (array < end) {
scalarResult = SkMinScalar(scalarResult, array->fOperand.fScalar);
array++;
}
break;
case SK_FUNCTION(pow):
// not the greatest -- but use x^y = e^(y * ln(x))
scalarResult = SkScalarLog(input);
scalarResult = SkScalarMul(parameters[1].fOperand.fScalar, scalarResult);
scalarResult = SkScalarExp(scalarResult);
break;
case SK_FUNCTION(random):
scalarResult = fRandom.nextUScalar1();
break;
case SK_FUNCTION(round):
scalarResult = SkIntToScalar(SkScalarRound(input));
break;
case SK_FUNCTION(sin):
scalarResult = SkScalarSin(input);
break;
case SK_FUNCTION(sqrt): {
SkASSERT(parameters.count() == 1);
SkASSERT(type == SkType_Float);
scalarResult = SkScalarSqrt(input);
} break;
case SK_FUNCTION(tan):
scalarResult = SkScalarTan(input);
break;
default:
SkASSERT(0);
scalarResult = SK_ScalarNaN;
}
scriptValue->fOperand.fScalar = scalarResult;
scriptValue->fType = SkType_Float;
}
