From 6482b8edd3ecdbf136692e910258dc452f8be71b Mon Sep 17 00:00:00 2001
From: yum <yum.food.vr@gmail.com>
Date: Thu, 6 Mar 2025 14:49:47 -0800
Subject: Add basic decal system

---
 decals.cginc | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 decals.cginc

(limited to 'decals.cginc')

diff --git a/decals.cginc b/decals.cginc
new file mode 100644
index 0000000..c356d45
--- /dev/null
+++ b/decals.cginc
@@ -0,0 +1,35 @@
+#ifndef __DECALS
+#define __DECALS
+
+#include "features.cginc"
+#include "globals.cginc"
+#include "math.cginc"
+
+void applyDecals(in v2f i, inout float4 albedo, inout float3 normal_tangent, inout float metallic, inout float smoothness) {
+#if defined(_DECAL0)
+  float2x2 decal0_rot = float2x2(
+    cos(_Decal0_Angle * TAU), -sin(_Decal0_Angle * TAU),
+    sin(_Decal0_Angle * TAU), cos(_Decal0_Angle * TAU)
+  );
+  float2 decal0_uv = mul(decal0_rot, i.uv01.xy);
+  decal0_uv = (decal0_uv * _Decal0_MainTex_ST.xy + _Decal0_MainTex_ST.zw) * _Decal0_Tiling_Mode;
+  decal0_uv = (_Decal0_Tiling_Mode == DECAL_TILING_MODE_CLAMP ? saturate(decal0_uv) : decal0_uv);
+
+  float4 decal0_albedo = _Decal0_MainTex.Sample(linear_repeat_s, decal0_uv) * _Decal0_Color;
+  decal0_albedo.a *= _Decal0_Opacity;
+  albedo = alphaBlend(albedo, decal0_albedo);
+
+#if defined(_DECAL0_NORMAL)
+  float3 decal0_normal = UnpackScaleNormal(
+    _Decal0_Normal.Sample(linear_repeat_s, decal0_uv), _Decal0_Normal_Scale * _Decal0_Opacity);
+  normal_tangent = blendNormalsHill12(normal_tangent, decal0_normal);
+#endif
+#if defined(_DECAL0_REFLECTIONS)
+  float4 metallic_gloss = _Decal0_MetallicGlossMap.Sample(linear_repeat_s, decal0_uv);
+  metallic = lerp(metallic, metallic_gloss.r * _Decal0_Metallic, decal0_albedo.a);
+  smoothness = lerp(smoothness, metallic_gloss.a * _Decal0_Smoothness, decal0_albedo.a);
+#endif
+#endif
+}
+
+#endif  // __DECALS
-- 
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