NewDevice creates a Device given an API, which is the necessary GPU
resources for a backend.
Convert gpu.New to take an API instead of a backend.Device directly.
In turn, this frees us to later unexport the backend package along with
the backend implementations (for now just gioui.org/gpu/gl for OpenGL).
It also allows programs that embed Gio (such as gioui.org/example/glfw)
to freely choose a backend, not just OpenGL.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Tweak a test color to avoid an off-by-1 rounding error after changing
the conversion formula.
Fixes gio#192
Signed-off-by: Elias Naur <mail@eliasnaur.com>
The Mesa software OpenGL implementation strays enough from the
reference values that tests fail. Relax the tests to make them
pass again.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
color.RGBA has two problems with regards to using it.
First the color values need to be premultiplied, whereas most APIs
have non-premultiplied values. This is mainly to preserve color components
with low alpha values.
Second there are two ways to premultiply with sRGB. One is to premultiply
after sRGB conversion, the other is before. This makes using the API more
confusing.
Using color.NRGBA in sRGB makes it align with CSS.e
Signed-off-by: Egon Elbre <egonelbre@gmail.com>
Specifying the clear color and depth at the time of clearing is
less error prone and a better for modern GPU APIs. As a bonus, we
can get rid of the BufferAttachment type.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Add a series of low level gpu.Backend tests to assure the correct behaviour of
Backends. The immediate use is debugging of the Direct3D port, in the future
for developing new backends.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Elias Naur