// reduce to a quadratic or smaller
// look for identical points
// look for all four points in a line
// note that three points in a line doesn't simplify a cubic
// look for approximation with single quadratic
// save approximation with multiple quadratics for later
int reduceOrder(const Cubic& cubic, Cubic& reduction, ReduceOrder_Quadratics allowQuadratics,
ReduceOrder_Styles reduceStyle) {
int index, minX, maxX, minY, maxY;
int minXSet, minYSet;
minX = maxX = minY = maxY = 0;
minXSet = minYSet = 0;
for (index = 1; index < 4; ++index) {
if (cubic[minX].x > cubic[index].x) {
minX = index;
}
if (cubic[minY].y > cubic[index].y) {
minY = index;
}
if (cubic[maxX].x < cubic[index].x) {
maxX = index;
}
if (cubic[maxY].y < cubic[index].y) {
maxY = index;
}
}
for (index = 0; index < 4; ++index) {
double cx = cubic[index].x;
double cy = cubic[index].y;
double denom = SkTMax(fabs(cx), SkTMax(fabs(cy),
SkTMax(fabs(cubic[minX].x), fabs(cubic[minY].y))));
if (denom == 0) {
minXSet |= 1 << index;
minYSet |= 1 << index;
continue;
}
double inv = 1 / denom;
if (approximately_equal_half(cx * inv, cubic[minX].x * inv)) {
minXSet |= 1 << index;
}
if (approximately_equal_half(cy * inv, cubic[minY].y * inv)) {
minYSet |= 1 << index;
}
}
if (minXSet == 0xF) { // test for vertical line
if (minYSet == 0xF) { // return 1 if all four are coincident
return coincident_line(cubic, reduction);
}
return vertical_line(cubic, reduceStyle, reduction);
}
if (minYSet == 0xF) { // test for horizontal line
return horizontal_line(cubic, reduceStyle, reduction);
}
int result = check_linear(cubic, reduceStyle, minX, maxX, minY, maxY, reduction);
if (result) {
return result;
}
if (allowQuadratics == kReduceOrder_QuadraticsAllowed
&& (result = check_quadratic(cubic, reduction))) {
return result;
}
memcpy(reduction, cubic, sizeof(Cubic));
return 4;
}
// reduce to a quadratic or smaller
// look for identical points
// look for all four points in a line
// note that three points in a line doesn't simplify a cubic
// look for approximation with single quadratic
// save approximation with multiple quadratics for later
int SkReduceOrder::reduce(const SkDCubic& cubic, Quadratics allowQuadratics) {
int index, minX, maxX, minY, maxY;
int minXSet, minYSet;
minX = maxX = minY = maxY = 0;
minXSet = minYSet = 0;
for (index = 1; index < 4; ++index) {
if (cubic[minX].fX > cubic[index].fX) {
minX = index;
}
if (cubic[minY].fY > cubic[index].fY) {
minY = index;
}
if (cubic[maxX].fX < cubic[index].fX) {
maxX = index;
}
if (cubic[maxY].fY < cubic[index].fY) {
maxY = index;
}
}
for (index = 0; index < 4; ++index) {
double cx = cubic[index].fX;
double cy = cubic[index].fY;
double denom = SkTMax(fabs(cx), SkTMax(fabs(cy),
SkTMax(fabs(cubic[minX].fX), fabs(cubic[minY].fY))));
if (denom == 0) {
minXSet |= 1 << index;
minYSet |= 1 << index;
continue;
}
double inv = 1 / denom;
if (approximately_equal_half(cx * inv, cubic[minX].fX * inv)) {
minXSet |= 1 << index;
}
if (approximately_equal_half(cy * inv, cubic[minY].fY * inv)) {
minYSet |= 1 << index;
}
}
if (minXSet == 0xF) { // test for vertical line
if (minYSet == 0xF) { // return 1 if all four are coincident
return coincident_line(cubic, fCubic);
}
return vertical_line(cubic, fCubic);
}
if (minYSet == 0xF) { // test for horizontal line
return horizontal_line(cubic, fCubic);
}
int result = check_linear(cubic, minX, maxX, minY, maxY, fCubic);
if (result) {
return result;
}
if (allowQuadratics == SkReduceOrder::kAllow_Quadratics
&& (result = check_quadratic(cubic, fCubic))) {
return result;
}
fCubic = cubic;
return 4;
}
// give up when changing t no longer moves point
// also, copy point rather than recompute it when it does change
double SkDCubic::binarySearch(double min, double max, double axisIntercept,
SearchAxis xAxis) const {
double t = (min + max) / 2;
double step = (t - min) / 2;
SkDPoint cubicAtT = ptAtT(t);
double calcPos = (&cubicAtT.fX)[xAxis];
double calcDist = calcPos - axisIntercept;
do {
double priorT = t - step;
SkOPASSERT(priorT >= min);
SkDPoint lessPt = ptAtT(priorT);
if (approximately_equal_half(lessPt.fX, cubicAtT.fX)
&& approximately_equal_half(lessPt.fY, cubicAtT.fY)) {
return -1; // binary search found no point at this axis intercept
}
double lessDist = (&lessPt.fX)[xAxis] - axisIntercept;
#if DEBUG_CUBIC_BINARY_SEARCH
SkDebugf("t=%1.9g calc=%1.9g dist=%1.9g step=%1.9g less=%1.9g\n", t, calcPos, calcDist,
step, lessDist);
#endif
double lastStep = step;
step /= 2;
if (calcDist > 0 ? calcDist > lessDist : calcDist < lessDist) {
t = priorT;
} else {
double nextT = t + lastStep;
if (nextT > max) {
return -1;
}
SkDPoint morePt = ptAtT(nextT);
if (approximately_equal_half(morePt.fX, cubicAtT.fX)
&& approximately_equal_half(morePt.fY, cubicAtT.fY)) {
return -1; // binary search found no point at this axis intercept
}
double moreDist = (&morePt.fX)[xAxis] - axisIntercept;
if (calcDist > 0 ? calcDist <= moreDist : calcDist >= moreDist) {
continue;
}
t = nextT;
}
SkDPoint testAtT = ptAtT(t);
cubicAtT = testAtT;
calcPos = (&cubicAtT.fX)[xAxis];
calcDist = calcPos - axisIntercept;
} while (!approximately_equal(calcPos, axisIntercept));
return t;
}
