blob: ff4aae445b745131eddac550ac6624b52d34b83f [file] [log] [blame]
/*
* Copyright 2018 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkCubicMap.h"
#include "SkGeometry.h"
#include "SkRandom.h"
#include "Test.h"
#include "../../src/pathops/SkPathOpsCubic.h"
static float accurate_t(float A, float B, float C, float D) {
double roots[3];
SkDEBUGCODE(int count =) SkDCubic::RootsValidT(A, B, C, D, roots);
SkASSERT(count == 1);
return (float)roots[0];
}
static float accurate_solve(SkPoint p1, SkPoint p2, SkScalar x) {
SkPoint array[] = { {0, 0}, p1, p2, {1,1} };
SkCubicCoeff coeff(array);
float t = accurate_t(coeff.fA[0], coeff.fB[0], coeff.fC[0], coeff.fD[0] - x);
SkASSERT(t >= 0 && t <= 1);
float y = coeff.eval(t)[1];
SkASSERT(y >= 0 && y <= 1.0001f);
return y;
}
static bool nearly_le(SkScalar a, SkScalar b) {
return a <= b || SkScalarNearlyZero(a - b);
}
static void exercise_cubicmap(SkPoint p1, SkPoint p2, skiatest::Reporter* reporter) {
const SkScalar MAX_SOLVER_ERR = 0.008f; // found by running w/ current impl
SkCubicMap cmap(p1, p2);
SkScalar prev_y = 0;
SkScalar dx = 1.0f / 512;
for (SkScalar x = dx; x < 1; x += dx) {
SkScalar y = cmap.computeYFromX(x);
// are we valid and (mostly) monotonic?
if (y < 0 || y > 1 || !nearly_le(prev_y, y)) {
cmap.computeYFromX(x);
REPORTER_ASSERT(reporter, false);
}
prev_y = y;
// are we close to the "correct" answer?
SkScalar yy = accurate_solve(p1, p2, x);
SkScalar diff = SkScalarAbs(yy - y);
REPORTER_ASSERT(reporter, diff < MAX_SOLVER_ERR);
}
}
DEF_TEST(CubicMap, r) {
const SkScalar values[] = {
0, 1, 0.5f, 0.0000001f, 0.999999f,
};
for (SkScalar x0 : values) {
for (SkScalar y0 : values) {
for (SkScalar x1 : values) {
for (SkScalar y1 : values) {
exercise_cubicmap({ x0, y0 }, { x1, y1 }, r);
}
}
}
}
}