vo_gpu: d3d11: add RA caps for ra_d3d11

ra_d3d11 uses the SPIR-V compiler to translate GLSL to SPIR-V, which is
then translated to HLSL. This means it always exposes the same GLSL
version that the SPIR-V compiler supports (4.50 for shaderc/glslang.)

Despite claiming to support GLSL 4.50, some features that are tied to
the GLSL version in OpenGL are not supported by ra_d3d11 when targeting
legacy Direct3D feature levels.

This includes two features that mpv relies on:
- Reading from gl_FragCoord in the fragment shader (requires FL 10_0)
- textureGather from any texture component (requires FL 11_0)

These features have been exposed as new RA caps.

1 files changed, 15 insertions, 1 deletions

diff --git a/video/out/gpu/video.c b/video/out/gpu/video.c
index fd870a2ffc..9cc889b401 100644
--- a/video/out/gpu/video.c
+++ b/video/out/gpu/video.c
@@ -1719,7 +1719,8 @@ static void pass_dispatch_sample_polar(struct gl_video *p, struct scaler *scaler
 fallback:
     // Fall back to regular polar shader when compute shaders are unsupported
     // or the kernel is too big for shmem
-    pass_sample_polar(p->sc, scaler, img.components, p->ra->glsl_version);
+    pass_sample_polar(p->sc, scaler, img.components,
+                      p->ra->caps & RA_CAP_GATHER);
 }
 
 // Sample from image, with the src rectangle given by it.
@@ -3465,6 +3466,19 @@ static void check_gl_features(struct gl_video *p)
         p->opts.compute_hdr_peak = 0;
         MP_WARN(p, "Disabling HDR peak computation (no compute shaders).\n");
     }
+    if (!(ra->caps & RA_CAP_FRAGCOORD) && p->opts.dither_depth >= 0 &&
+        p->opts.dither_algo != DITHER_NONE)
+    {
+        p->opts.dither_algo = DITHER_NONE;
+        MP_WARN(p, "Disabling dithering (no gl_FragCoord).\n");
+    }
+    if (!(ra->caps & RA_CAP_FRAGCOORD) &&
+        p->opts.alpha_mode == ALPHA_BLEND_TILES)
+    {
+        p->opts.alpha_mode = ALPHA_BLEND;
+        // Verbose, since this is the default setting
+        MP_VERBOSE(p, "Disabling alpha checkerboard (no gl_FragCoord).\n");
+    }
 }
 
 static void init_gl(struct gl_video *p)