We were invoking `frac_int_range` twice to get the `alpha` and `beta`
values to interpolate between 4 texels, but these call into
`floor_int_range` again. Let's not repeat the work.
On every texel access, some floating point instructions involved in
copying 4 floats popped up. Let `Image::texel() const` return a
`FloatVector4 const&` to prevent these operations.
This results in a ~7% FPS increase in GLQuake on my machine.
Looking at how Khronos defines layers:
https://www.khronos.org/opengl/wiki/Array_Texture
We both have 3D textures and layers of 2D textures, which can both be
encoded in our existing `Typed3DBuffer` as depth. Since we support
depth already in the GPU API, remove layer everywhere.
Also pass in `Texture2D::LOG2_MAX_TEXTURE_SIZE` as the maximum number
of mipmap levels, so we do not allocate 999 levels on each Image
instantiation.
`GL_COMBINE` is basically a fixed function calculator to perform simple
arithmetics on configurable fragment sources. This patch implements a
number of texture env parameters with support for the RGBA internal
format.
This introduces a new device independent base class for Images in LibGPU
that also keeps track of the device from which it was created in order
to prevent assigning images across devices.
Previously the test determining whether to use texture maginifaction or
texture minification was reversed. This commit fixes the test and also
provides an early out of the sampler in case of texture magnification
since magnification does not make use of mipmaps.
According to the Khronos FAQ on texture edge sampling, the `GL_CLAMP`
option was never implemented in hardware and as such, it was
deprecated. A lot of applications and games depend on `GL_CLAMP` not
really meaning `GL_CLAMP` but `GL_CLAMP_TO_EDGE`, so we introduce an
option to toggle this behavior at compile-time.
