work in progress
in the middle of switching to sortless version
git-svn-id: http://skia.googlecode.com/svn/trunk@3768 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/experimental/Intersection/LineQuadraticIntersection.cpp b/experimental/Intersection/LineQuadraticIntersection.cpp
index 737b767..1bc831b 100644
--- a/experimental/Intersection/LineQuadraticIntersection.cpp
+++ b/experimental/Intersection/LineQuadraticIntersection.cpp
@@ -141,6 +141,16 @@
return quadraticRoots(D, E, F, intersections.fT[0]);
}
+int verticalIntersect(double axisIntercept) {
+ double D = quad[2].x; // f
+ double E = quad[1].x; // e
+ double F = quad[0].x; // d
+ D += F - 2 * E; // D = d - 2*e + f
+ E -= F; // E = -(d - e)
+ F -= axisIntercept;
+ return quadraticRoots(D, E, F, intersections.fT[0]);
+}
+
protected:
double findLineT(double t) {
@@ -167,6 +177,46 @@
};
+// utility for pairs of coincident quads
+static double horizontalIntersect(const Quadratic& quad, const _Point& pt) {
+ Intersections intersections;
+ LineQuadraticIntersections q(quad, *((_Line*) 0), intersections);
+ int result = q.horizontalIntersect(pt.y);
+ if (result == 0) {
+ return -1;
+ }
+ assert(result == 1);
+ double x, y;
+ xy_at_t(quad, intersections.fT[0][0], x, y);
+ if (approximately_equal(x, pt.x)) {
+ return intersections.fT[0][0];
+ }
+ return -1;
+}
+
+static double verticalIntersect(const Quadratic& quad, const _Point& pt) {
+ Intersections intersections;
+ LineQuadraticIntersections q(quad, *((_Line*) 0), intersections);
+ int result = q.horizontalIntersect(pt.x);
+ if (result == 0) {
+ return -1;
+ }
+ assert(result == 1);
+ double x, y;
+ xy_at_t(quad, intersections.fT[0][0], x, y);
+ if (approximately_equal(y, pt.y)) {
+ return intersections.fT[0][0];
+ }
+ return -1;
+}
+
+double axialIntersect(const Quadratic& q1, const _Point& p, bool vertical) {
+ if (vertical) {
+ return verticalIntersect(q1, p);
+ }
+ return horizontalIntersect(q1, p);
+}
+
int horizontalIntersect(const Quadratic& quad, double left, double right,
double y, double tRange[2]) {
Intersections i;
@@ -184,6 +234,56 @@
return tCount;
}
+int horizontalIntersect(const Quadratic& quad, double left, double right, double y,
+ bool flipped, Intersections& intersections) {
+ LineQuadraticIntersections q(quad, *((_Line*) 0), intersections);
+ int result = q.horizontalIntersect(y);
+ for (int index = 0; index < result; ) {
+ double x, y;
+ xy_at_t(quad, intersections.fT[0][index], x, y);
+ if (x < left || x > right) {
+ if (--result > index) {
+ intersections.fT[0][index] = intersections.fT[0][result];
+ }
+ continue;
+ }
+ intersections.fT[0][index] = (x - left) / (right - left);
+ ++index;
+ }
+ if (flipped) {
+ // OPTIMIZATION: instead of swapping, pass original line, use [1].x - [0].x
+ for (int index = 0; index < result; ++index) {
+ intersections.fT[1][index] = 1 - intersections.fT[1][index];
+ }
+ }
+ return result;
+}
+
+int verticalIntersect(const Quadratic& quad, double top, double bottom, double x,
+ bool flipped, Intersections& intersections) {
+ LineQuadraticIntersections q(quad, *((_Line*) 0), intersections);
+ int result = q.verticalIntersect(x);
+ for (int index = 0; index < result; ) {
+ double x, y;
+ xy_at_t(quad, intersections.fT[0][index], x, y);
+ if (y < top || y > bottom) {
+ if (--result > index) {
+ intersections.fT[0][index] = intersections.fT[0][result];
+ }
+ continue;
+ }
+ intersections.fT[0][index] = (y - top) / (bottom - top);
+ ++index;
+ }
+ if (flipped) {
+ // OPTIMIZATION: instead of swapping, pass original line, use [1].x - [0].x
+ for (int index = 0; index < result; ++index) {
+ intersections.fT[1][index] = 1 - intersections.fT[1][index];
+ }
+ }
+ return result;
+}
+
bool intersect(const Quadratic& quad, const _Line& line, Intersections& i) {
LineQuadraticIntersections q(quad, line, i);
return q.intersect();