void SkNormalMapSourceImpl::Provider::fillScanLine(int x, int y, SkPoint3 output[],
int count) const {
SkPMColor tmpNormalColors[BUFFER_MAX];
do {
int n = SkTMin(count, BUFFER_MAX);
fMapContext->shadeSpan(x, y, tmpNormalColors, n);
for (int i = 0; i < n; i++) {
SkPoint3 tempNorm;
tempNorm.set(SkIntToScalar(SkGetPackedR32(tmpNormalColors[i])) - 127.0f,
SkIntToScalar(SkGetPackedG32(tmpNormalColors[i])) - 127.0f,
SkIntToScalar(SkGetPackedB32(tmpNormalColors[i])) - 127.0f);
tempNorm.normalize();
if (!SkScalarNearlyEqual(SkScalarAbs(tempNorm.fZ), 1.0f)) {
SkVector transformed = fSource.fInvCTM.mapVector(tempNorm.fX, tempNorm.fY);
// Normalizing the transformed X and Y, while keeping constant both Z and the
// vector's angle in the XY plane. This maintains the "slope" for the surface while
// appropriately rotating the normal for any anisotropic scaling that occurs.
// Here, we call scaling factor the number that must divide the transformed X and Y
// so that the normal's length remains equal to 1.
SkScalar scalingFactorSquared =
(SkScalarSquare(transformed.fX) + SkScalarSquare(transformed.fY))
/ (1.0f - SkScalarSquare(tempNorm.fZ));
SkScalar invScalingFactor = SkScalarInvert(SkScalarSqrt(scalingFactorSquared));
output[i].fX = transformed.fX * invScalingFactor;
output[i].fY = transformed.fY * invScalingFactor;
output[i].fZ = tempNorm.fZ;
} else {
output[i] = {0.0f, 0.0f, tempNorm.fZ};
output[i].normalize();
}
SkASSERT(SkScalarNearlyEqual(output[i].length(), 1.0f));
}
output += n;
x += n;
count -= n;
} while (count > 0);
}
void create_frustum_normal_map(SkBitmap* bm, const SkIRect& dst) {
const SkPoint center = SkPoint::Make(dst.fLeft + (dst.width() / 2.0f),
dst.fTop + (dst.height() / 2.0f));
SkIRect inner = dst;
inner.inset(dst.width()/4, dst.height()/4);
SkPoint3 norm;
const SkPoint3 left = SkPoint3::Make(-SK_ScalarRoot2Over2, 0.0f, SK_ScalarRoot2Over2);
const SkPoint3 up = SkPoint3::Make(0.0f, -SK_ScalarRoot2Over2, SK_ScalarRoot2Over2);
const SkPoint3 right = SkPoint3::Make(SK_ScalarRoot2Over2, 0.0f, SK_ScalarRoot2Over2);
const SkPoint3 down = SkPoint3::Make(0.0f, SK_ScalarRoot2Over2, SK_ScalarRoot2Over2);
for (int y = dst.fTop; y < dst.fBottom; ++y) {
for (int x = dst.fLeft; x < dst.fRight; ++x) {
if (inner.contains(x, y)) {
norm.set(0.0f, 0.0f, 1.0f);
} else {
SkScalar locX = x + 0.5f - center.fX;
SkScalar locY = y + 0.5f - center.fY;
if (locX >= 0.0f) {
if (locY > 0.0f) {
norm = locX >= locY ? right : down; // LR corner
} else {
norm = locX > -locY ? right : up; // UR corner
}
} else {
if (locY > 0.0f) {
norm = -locX > locY ? left : down; // LL corner
} else {
norm = locX > locY ? up : left; // UL corner
}
}
}
norm_to_rgb(bm, x, y, norm);
}
}
}
