skia2/tests/PathOpsCubicLineIntersectionTest.cpp
caryclark@google.com 9166dcb3a0 Add intersections for path ops
This CL depends on 
https://codereview.chromium.org/12827020/
"Add base types for path ops"

The intersection of a line, quadratic, or cubic
with another curve (or with itself) is found by
solving the implicit equation for the curve pair.

The curves are first reduced to find the simplest
form that will describe the original, and to detect
degenerate or special-case data like horizontal and
vertical lines.

For cubic self-intersection, and for a pair of cubics,
the intersection is found by recursively
approximating the cubic with a series of quadratics.

The implicit solutions depend on the root finding
contained in the DCubic and DQuad structs, and
the quartic root finder included here.
Review URL: https://codereview.chromium.org/12880016

git-svn-id: http://skia.googlecode.com/svn/trunk@8552 2bbb7eff-a529-9590-31e7-b0007b416f81
2013-04-08 11:50:00 +00:00

62 lines
2.2 KiB
C++

/*
* Copyright 2012 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkIntersections.h"
#include "SkPathOpsCubic.h"
#include "SkPathOpsLine.h"
#include "SkReduceOrder.h"
#include "Test.h"
static struct lineCubic {
SkDCubic cubic;
SkDLine line;
} lineCubicTests[] = {
{{{{1, 2}, {2, 6}, {2, 0}, {1, 0}}}, {{{1, 0}, {1, 2}}}},
{{{{0, 0}, {0, 1}, {0, 1}, {1, 1}}}, {{{0, 1}, {1, 0}}}},
};
static const size_t lineCubicTests_count = sizeof(lineCubicTests) / sizeof(lineCubicTests[0]);
static void CubicLineIntersectionTest(skiatest::Reporter* reporter) {
for (size_t index = 0; index < lineCubicTests_count; ++index) {
int iIndex = static_cast<int>(index);
const SkDCubic& cubic = lineCubicTests[index].cubic;
const SkDLine& line = lineCubicTests[index].line;
SkReduceOrder reduce1;
SkReduceOrder reduce2;
int order1 = reduce1.reduce(cubic, SkReduceOrder::kNo_Quadratics,
SkReduceOrder::kFill_Style);
int order2 = reduce2.reduce(line);
if (order1 < 4) {
SkDebugf("[%d] cubic order=%d\n", iIndex, order1);
REPORTER_ASSERT(reporter, 0);
}
if (order2 < 2) {
SkDebugf("[%d] line order=%d\n", iIndex, order2);
REPORTER_ASSERT(reporter, 0);
}
if (order1 == 4 && order2 == 2) {
SkIntersections i;
int roots = i.intersect(cubic, line);
for (int pt = 0; pt < roots; ++pt) {
double tt1 = i[0][pt];
SkDPoint xy1 = cubic.xyAtT(tt1);
double tt2 = i[1][pt];
SkDPoint xy2 = line.xyAtT(tt2);
if (!xy1.approximatelyEqual(xy2)) {
SkDebugf("%s [%d,%d] x!= t1=%g (%g,%g) t2=%g (%g,%g)\n",
__FUNCTION__, iIndex, pt, tt1, xy1.fX, xy1.fY, tt2, xy2.fX, xy2.fY);
}
REPORTER_ASSERT(reporter, xy1.approximatelyEqual(xy2));
}
}
}
}
#include "TestClassDef.h"
DEFINE_TESTCLASS("PathOpsCubicLineIntersection", CubicLineIntersectionTestClass, \
CubicLineIntersectionTest)