Black screen when using Crtsim.glsp/composite.glsl

[Denshadego]

When using the shader preset crt/crtsim, specifically composite.glsl, with hardware accelerated cores (Flycast, mupen), the screen is totally black with the game working normally in the background. In all the other cores it works normally.
When selecting per-pixel alpha sorting in Flycast, apart from the black screen, sometimes causes a strobing light effect with the black screen coming in and out.
Tested on windows 10/7 and android using gl.

[hizzlekizzle]

As I wrote on the forum (copying here for future reference): it looks like it’s related to the Prev*Texture. It appears that the same thing happens with other shaders that use that, such as motionblur-simple.

So, bigger issue than just the one shader, but that makes it easier to test and trackdown, too.