// Solves linear system to extract klm
// P.K = k (similarly for l, m)
// Where P is matrix of control points
// K is coefficients for the line K
// k is vector of values of K evaluated at the control points
// Solving for K, thus K = P^(-1) . k
static void calc_cubic_klm(const SkPoint p[4], const SkScalar controlK[4],
const SkScalar controlL[4], const SkScalar controlM[4],
SkScalar k[3], SkScalar l[3], SkScalar m[3]) {
SkMatrix matrix;
matrix.setAll(p[0].fX, p[0].fY, 1.f,
p[1].fX, p[1].fY, 1.f,
p[2].fX, p[2].fY, 1.f);
SkMatrix inverse;
if (matrix.invert(&inverse)) {
inverse.mapHomogeneousPoints(k, controlK, 1);
inverse.mapHomogeneousPoints(l, controlL, 1);
inverse.mapHomogeneousPoints(m, controlM, 1);
}
}
// Equations based off of Loop-Blinn Quadratic GPU Rendering
// Input Parametric:
// P(t) = (P0*(1-t)^2 + 2*w*P1*t*(1-t) + P2*t^2) / (1-t)^2 + 2*w*t*(1-t) + t^2)
// Output Implicit:
// f(x, y, w) = f(P) = K^2 - LM
// K = dot(k, P), L = dot(l, P), M = dot(m, P)
// k, l, m are calculated in function GrPathUtils::getConicKLM
static void set_conic_coeffs(const SkPoint p[3], BezierVertex verts[kQuadNumVertices],
const SkScalar weight) {
SkMatrix klm;
GrPathUtils::getConicKLM(p, weight, &klm);
for (int i = 0; i < kQuadNumVertices; ++i) {
const SkPoint3 pt3 = {verts[i].fPos.x(), verts[i].fPos.y(), 1.f};
klm.mapHomogeneousPoints((SkPoint3* ) verts[i].fConic.fKLM, &pt3, 1);
}
}
static void test_matrix_homogeneous(skiatest::Reporter* reporter) {
SkMatrix mat;
const float kRotation0 = 15.5f;
const float kRotation1 = -50.f;
const float kScale0 = 5000.f;
const int kTripleCount = 1000;
const int kMatrixCount = 1000;
SkRandom rand;
SkScalar randTriples[3*kTripleCount];
for (int i = 0; i < 3*kTripleCount; ++i) {
randTriples[i] = rand.nextRangeF(-3000.f, 3000.f);
}
SkMatrix mats[kMatrixCount];
for (int i = 0; i < kMatrixCount; ++i) {
for (int j = 0; j < 9; ++j) {
mats[i].set(j, rand.nextRangeF(-3000.f, 3000.f));
}
}
// identity
{
mat.reset();
SkScalar dst[3*kTripleCount];
mat.mapHomogeneousPoints(dst, randTriples, kTripleCount);
REPORTER_ASSERT(reporter, scalar_array_nearly_equal_relative(randTriples, dst, kTripleCount*3));
}
// zero matrix
{
mat.setAll(0.f, 0.f, 0.f, 0.f, 0.f, 0.f, 0.f, 0.f, 0.f);
SkScalar dst[3*kTripleCount];
mat.mapHomogeneousPoints(dst, randTriples, kTripleCount);
SkScalar zeros[3] = {0.f, 0.f, 0.f};
for (int i = 0; i < kTripleCount; ++i) {
REPORTER_ASSERT(reporter, scalar_array_nearly_equal_relative(&dst[i*3], zeros, 3));
}
}
// zero point
{
SkScalar zeros[3] = {0.f, 0.f, 0.f};
for (int i = 0; i < kMatrixCount; ++i) {
SkScalar dst[3];
mats[i].mapHomogeneousPoints(dst, zeros, 1);
REPORTER_ASSERT(reporter, scalar_array_nearly_equal_relative(dst, zeros, 3));
}
}
// doesn't crash with null dst, src, count == 0
{
mats[0].mapHomogeneousPoints(NULL, NULL, 0);
}
// uniform scale of point
{
mat.setScale(kScale0, kScale0);
SkScalar dst[3];
SkScalar src[3] = {randTriples[0], randTriples[1], 1.f};
SkPoint pnt;
pnt.set(src[0], src[1]);
mat.mapHomogeneousPoints(dst, src, 1);
mat.mapPoints(&pnt, &pnt, 1);
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(dst[0], pnt.fX));
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(dst[1], pnt.fY));
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(dst[2], SK_Scalar1));
}
// rotation of point
{
mat.setRotate(kRotation0);
SkScalar dst[3];
SkScalar src[3] = {randTriples[0], randTriples[1], 1.f};
SkPoint pnt;
pnt.set(src[0], src[1]);
mat.mapHomogeneousPoints(dst, src, 1);
mat.mapPoints(&pnt, &pnt, 1);
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(dst[0], pnt.fX));
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(dst[1], pnt.fY));
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(dst[2], SK_Scalar1));
}
// rotation, scale, rotation of point
{
mat.setRotate(kRotation1);
mat.postScale(kScale0, kScale0);
mat.postRotate(kRotation0);
SkScalar dst[3];
SkScalar src[3] = {randTriples[0], randTriples[1], 1.f};
SkPoint pnt;
pnt.set(src[0], src[1]);
mat.mapHomogeneousPoints(dst, src, 1);
mat.mapPoints(&pnt, &pnt, 1);
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(dst[0], pnt.fX));
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(dst[1], pnt.fY));
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(dst[2], SK_Scalar1));
}
// compare with naive approach
{
for (int i = 0; i < kMatrixCount; ++i) {
for (int j = 0; j < kTripleCount; ++j) {
SkScalar dst[3];
mats[i].mapHomogeneousPoints(dst, &randTriples[j*3], 1);
REPORTER_ASSERT(reporter, naive_homogeneous_mapping(mats[i], &randTriples[j*3], dst));
}
}
}
}
