Re: [PATCH 5/5] d2d1: Implement initial support for quadratic bezier outlines.

[Dmitry Timoshkov]

Henri Verbeet  wrote:
> > > +static void d2d_point_lerp(D2D1_POINT_2F *out,
> > > -
> > >    const D2D1_POINT_2F *a, const D2D1_POINT_2F *b, float t)
> > >
> > > +{
> > > - out->x = a->x * (1.0f - t) + b->x * t;
> > > - out->y = a->y * (1.0f - t) + b->y * t;
> > >
> > > +}
> >
> > According to my investigation of a better bilinear blending (lerp)
> > implementation the above formula is better to explicitely simplify
> > to
> >
> > out->x = a->x + (b->x - a->x) * t;
> > out->y = a->y + (b->y - a->y) * t;
>
> For performance, quite possibly. This isn't particularly performance
> sensitive code though, and I'd be surprised if that variant had better
> accuracy.

I'd dare to claim that both variants should be equivalent in accuracy,
and the 2nd version just avoids a redundant mutiplication.