From 8b7ae8db808d76ddea503f94e142c7d37c1b43d3 Mon Sep 17 00:00:00 2001
From: yum <yum.food.vr@gmail.com>
Date: Thu, 5 Jun 2025 19:42:36 -0700
Subject: more  work on fog & c30

---
 decals.cginc | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

(limited to 'decals.cginc')

diff --git a/decals.cginc b/decals.cginc
index cd71c73..b4f1151 100644
--- a/decals.cginc
+++ b/decals.cginc
@@ -89,7 +89,15 @@ float4 getDecalColor(DecalParams params, float2 uv) {
     float4 sdf_sample = params.mainTex.SampleLevel(linear_repeat_s, uv, 0);
     float sd = sdf_sample.r;
     sd = params.sdf_invert ? 1 - sd : sd;
-    sd = (sd > params.sdf_threshold ? 1 : 0);
+    // The fwidth+smoothstep anti-aliases the glyph outline. See
+    // "Noise is Beautiful" by Gustavson around page 34 for an
+    // explanation of this trick.
+#if 1
+    float step_wd = fwidth(sd) * 0.5;
+    sd = smoothstep(params.sdf_threshold - step_wd, params.sdf_threshold + step_wd, sd);
+#else
+    sd = step(params.sdf_threshold, sd);
+#endif
     return params.color * sd;
 }
 
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