zfast-crt: add preset for the coarse mask, suitable for HD displays

To avoid duplicating the whole shader implementation, the needed define
has been split into its own file, and the shader implementation is now
in an include file.

crt/shaders/zfast_crt/zfast_crt_coarsemask.slang

@@ -0,0 +1,3 @@
+#version 450
+
+#include "zfast_crt_impl.inc"

crt/shaders/zfast_crt/zfast_crt_finemask.slang

@@ -0,0 +1,8 @@
+#version 450
+
+// This can't be an option without slowing the shader down.
+// Note that only the fine mask works on SNES Classic Edition
+// due to Mali 400 gpu precision.
+#define FINEMASK
+
+#include "zfast_crt_impl.inc"

crt/shaders/zfast_crt/zfast_crt_impl.inc

@@ -1,5 +1,3 @@
-#version 450
-
 /*
     zfast_crt_standard - A simple, fast CRT shader.
 
@@ -52,10 +50,6 @@ layout(std140, set = 0, binding = 0) uniform UBO
 //#define FRAGMENT
 //#define VERTEX
 
-//This can't be an option without slowing the shader down
-//Comment this out for a coarser 3 pixel mask...which is currently broken
-//on SNES Classic Edition due to Mali 400 gpu precision
-#define FINEMASK
 //Some drivers don't return black with texture coordinates out of bounds
 //SNES Classic is too slow to black these areas out when using fullscreen
 //overlays.  But you can uncomment the below to black them out if necessary

crt/zfast-crt-hdmask.slangp

@@ -0,0 +1,4 @@
+shaders = 1
+
+shader0 = shaders/zfast_crt/zfast_crt_coarsemask.slang
+filter_linear0 = true

crt/zfast-crt.slangp

@@ -1,4 +1,4 @@
 shaders = 1
 
-shader0 = shaders/zfast_crt.slang
+shader0 = shaders/zfast_crt/zfast_crt_finemask.slang
 filter_linear0 = true