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/LineIntersection.cpp b/experimental/Intersection/LineIntersection.cpp
index f5128ea..40e046c 100644
--- a/experimental/Intersection/LineIntersection.cpp
+++ b/experimental/Intersection/LineIntersection.cpp
@@ -1,4 +1,5 @@
#include "DataTypes.h"
+#include "Intersections.h"
#include "LineIntersection.h"
#include <algorithm> // used for std::swap
@@ -112,9 +113,9 @@
double y, double tRange[2]) {
int result = horizontalIntersect(line, y, tRange);
if (result != 1) {
+ // FIXME: this is incorrect if result == 2
return result;
}
- // FIXME: this is incorrect if result == 2
double xIntercept = line[0].x + tRange[0] * (line[1].x - line[0].x);
if (xIntercept > right || xIntercept < left) {
return 0;
@@ -122,6 +123,116 @@
return result;
}
+int horizontalIntersect(const _Line& line, double left, double right,
+ double y, bool flipped, Intersections& intersections) {
+ int result = horizontalIntersect(line, y, intersections.fT[0]);
+ switch (result) {
+ case 0:
+ break;
+ case 1: {
+ double xIntercept = line[0].x + intersections.fT[0][0]
+ * (line[1].x - line[0].x);
+ if (xIntercept > right || xIntercept < left) {
+ return 0;
+ }
+ intersections.fT[1][0] = (xIntercept - left) / (right - left);
+ break;
+ }
+ case 2:
+ double lineL = line[0].x;
+ double lineR = line[1].x;
+ if (lineL > lineR) {
+ std::swap(lineL, lineR);
+ }
+ double overlapL = std::max(left, lineL);
+ double overlapR = std::min(right, lineR);
+ if (overlapL > overlapR) {
+ return 0;
+ }
+ if (overlapL == overlapR) {
+ result = 1;
+ }
+ intersections.fT[0][0] = (overlapL - line[0].x) / (line[1].x - line[0].x);
+ intersections.fT[1][0] = (overlapL - left) / (right - left);
+ if (result > 1) {
+ intersections.fT[0][1] = (overlapR - line[0].x) / (line[1].x - line[0].x);
+ intersections.fT[1][1] = (overlapR - left) / (right - left);
+ }
+ break;
+ }
+ 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 _Line& line, double x, double tRange[2]) {
+ double min = line[0].x;
+ double max = line[1].x;
+ if (min > max) {
+ std::swap(min, max);
+ }
+ if (min > x || max < x) {
+ return 0;
+ }
+ if (approximately_equal(min, max)) {
+ tRange[0] = 0;
+ tRange[1] = 1;
+ return 2;
+ }
+ tRange[0] = (x - line[0].x) / (line[1].x - line[0].x);
+ return 1;
+}
+
+int verticalIntersect(const _Line& line, double top, double bottom,
+ double x, bool flipped, Intersections& intersections) {
+ int result = verticalIntersect(line, x, intersections.fT[0]);
+ switch (result) {
+ case 0:
+ break;
+ case 1: {
+ double yIntercept = line[0].y + intersections.fT[0][0]
+ * (line[1].y - line[0].y);
+ if (yIntercept > bottom || yIntercept < top) {
+ return 0;
+ }
+ intersections.fT[1][0] = (yIntercept - top) / (bottom - top);
+ break;
+ }
+ case 2:
+ double lineT = line[0].y;
+ double lineB = line[1].y;
+ if (lineT > lineB) {
+ std::swap(lineT, lineB);
+ }
+ double overlapT = std::max(top, lineT);
+ double overlapB = std::min(bottom, lineB);
+ if (overlapT > overlapB) {
+ return 0;
+ }
+ if (overlapT == overlapB) {
+ result = 1;
+ }
+ intersections.fT[0][0] = (overlapT - line[0].y) / (line[1].y - line[0].y);
+ intersections.fT[1][0] = (overlapT - top) / (bottom - top);
+ if (result > 1) {
+ intersections.fT[0][1] = (overlapB - line[0].y) / (line[1].y - line[0].y);
+ intersections.fT[1][1] = (overlapB - top) / (bottom - top);
+ }
+ break;
+ }
+ if (flipped) {
+ // OPTIMIZATION: instead of swapping, pass original line, use [1].y - [0].y
+ for (int index = 0; index < result; ++index) {
+ intersections.fT[1][index] = 1 - intersections.fT[1][index];
+ }
+ }
+ return result;
+}
+
// from http://www.bryceboe.com/wordpress/wp-content/uploads/2006/10/intersect.py
// 4 subs, 2 muls, 1 cmp
static bool ccw(const _Point& A, const _Point& B, const _Point& C) {