void SkUnit3D::Cross(const SkUnit3D& a, const SkUnit3D& b, SkUnit3D* cross) {
SkASSERT(cross);
// use x,y,z, in case &a == cross or &b == cross
SkScalar x = SkUnitScalarMul(a.fY, b.fZ) - SkUnitScalarMul(a.fZ, b.fY);
SkScalar y = SkUnitScalarMul(a.fZ, b.fX) - SkUnitScalarMul(a.fX, b.fY);
SkScalar z = SkUnitScalarMul(a.fX, b.fY) - SkUnitScalarMul(a.fY, b.fX);
cross->set(x, y, z);
}
void SkCamera3D::doUpdate() const
{
SkUnit3D axis, zenith, cross;
fAxis.normalize(&axis);
{
SkScalar dot = SkUnit3D::Dot(*(const SkUnit3D*)(const void*)&fZenith, axis);
zenith.fX = fZenith.fX - SkUnitScalarMul(dot, axis.fX);
zenith.fY = fZenith.fY - SkUnitScalarMul(dot, axis.fY);
zenith.fZ = fZenith.fZ - SkUnitScalarMul(dot, axis.fZ);
(void)((SkPoint3D*)(void*)&zenith)->normalize(&zenith);
}
SkUnit3D::Cross(axis, zenith, &cross);
{
SkMatrix* orien = &fOrientation;
SkScalar x = fObserver.fX;
SkScalar y = fObserver.fY;
SkScalar z = fObserver.fZ;
orien->set(SkMatrix::kMScaleX, SkUnitScalarMul(x, axis.fX) - SkUnitScalarMul(z, cross.fX));
orien->set(SkMatrix::kMSkewX, SkUnitScalarMul(x, axis.fY) - SkUnitScalarMul(z, cross.fY));
orien->set(SkMatrix::kMTransX, SkUnitScalarMul(x, axis.fZ) - SkUnitScalarMul(z, cross.fZ));
orien->set(SkMatrix::kMSkewY, SkUnitScalarMul(y, axis.fX) - SkUnitScalarMul(z, zenith.fX));
orien->set(SkMatrix::kMScaleY, SkUnitScalarMul(y, axis.fY) - SkUnitScalarMul(z, zenith.fY));
orien->set(SkMatrix::kMTransY, SkUnitScalarMul(y, axis.fZ) - SkUnitScalarMul(z, zenith.fZ));
orien->set(SkMatrix::kMPersp0, axis.fX);
orien->set(SkMatrix::kMPersp1, axis.fY);
orien->set(SkMatrix::kMPersp2, axis.fZ);
}
}
SkUnitScalar SkUnit3D::Dot(const SkUnit3D& a, const SkUnit3D& b)
{
return SkUnitScalarMul(a.fX, b.fX) +
SkUnitScalarMul(a.fY, b.fY) +
SkUnitScalarMul(a.fZ, b.fZ);
}
