Call `glViewport()` once when initializing the backend with the maximum
supported dimensions. Since all shaders are equipped with the
corresponding projection matrix, the viewport does not have to be
updated prior to each draw call.
Related: a7bd48f5ab
Set viewport in `gl_average_texture_color()` to global `vp_width` and
`vp_height` as the projection matrix has been initialized to these dimensions
as well.
Related: a7bd48f5ab
- Query maximum supported dimensions of `glViewport()` when initializing
so we don't have to worry about differently sized textures when
rendering (usually the same as the maximum supported texture size, but
dependend on the driver).
- Set projection matrix in all shaders at startup to queried viewport
dimensions. Allows using screen coordinates for all vertex positions
without having to keep track of framebuffer dimensions.
- Follow recommendations and set `glViewport()` to queried maximum dimensions
for each draw call (`glDraw*()`, `glClear()`).
Related: #349
Handle more (hopefully all) edge-cases when updating `opacity_target_old`:
* `MAPPING` transitions to `FADING` if new target is reached. Otherwise
no update.
* `FADING` clamps to current `opacity` if old target is too small.
* `UNMAPPING`/`DESTROYING` clamps to current `opacity` if old target is
too small.
* Add new field `opacity_target_old` to `struct managed_win` for
tracking relevant `opacity_target` changes.
* Smoothly fade blur-texture opacity on window opacity changes (based on
window opacity), when the window was or will be fully transparent
(`w->opacity ~< 0.004`).
* Fixed alpha-clipping of the blur-texture when using `inactive-opacity` or
repeatedly setting window opacity with large fade intervals (should fix#314).
Bernd Busse