[PATCH 2/2] protocol: Add buffer_scale to wl_surface and wl_output

[Pekka Paalanen]

On Tue, 14 May 2013 12:48:39 -0700
Bill Spitzak <spitzak at gmail.com> wrote:

> Pekka Paalanen wrote:
> 
> > You cannot get an identity by multiplying real-valued transformations
> > together, other than by accident.
> 
> This is why I propose sending the inverse of the matrix, so the identity 
> can be checked accurately. It also happens that the inverse matrix is 
> the same matrix that is needed to tell cairo to draw the image correctly.
> 

A matrix naively multiplied by its inverse matrix is not identity, so
you cannot simply check it.

Also, checking whether two matrices are equal is *hard*. Do not go
there.

This proposal does not belong in this thread. Really.

- pq