fix normal bugs, add normal shadowing

going to remove normal shadowing, it's not worth the complexity

1 files changed, 89 insertions, 0 deletions

diff --git a/filamented.cginc b/filamented.cginc
index 2b1e876..b2f2ddb 100644
--- a/filamented.cginc
+++ b/filamented.cginc
@@ -389,5 +389,94 @@ inline half3 UnityGI_prefilteredRadiance(const UnityGIInput data,
   return specular;
 }
 
+// R dither mask
+float noiseR2(float2 pixel) {
+  const float a1 = 0.75487766624669276;
+  const float a2 = 0.569840290998;
+  return frac(a1 * float(pixel.x) + a2 * float(pixel.y));
+}
+
+#if defined(_BUMP_SHADOWS)
+struct NormalMapShadowsParam
+{
+  float4 uv;
+  float2 dX;
+  float2 dY;
+};
+
+NormalMapShadowsParam InitNormalMapShadowsParam(float4 uv)
+{
+  NormalMapShadowsParam nms;
+
+  nms.uv = uv;
+  nms.dX = ddx(uv.xy);
+  nms.dY = ddy(uv.xy);
+
+  return nms;
+}
+
+// Ref: Normal Mapping Shadows by Boris Vorontsov
+// Please define a NormalMapShadowsParam parameter
+// and SampleNormalMap function to sample the normal map.
+float NormalMapShadows (float3 lightDirTangent, NormalMapShadowsParam nmsParam, float noise,
+	float heightScale, float shadowHardness)
+{
+	const float screenShadowSamples = 20;
+	const float hardness = heightScale * shadowHardness;
+	const float sampleStep = 1.0 / screenShadowSamples;
+
+	float2 dir = lightDirTangent.xy * heightScale;
+
+	// Redundancy can't be helped
+  float3 normal = UnpackScaleNormal(tex2D(_BumpMap, nmsParam.uv), _BumpScale);
+
+	lightDirTangent = normalize(lightDirTangent);
+    float tangentNdotL = saturate(dot(lightDirTangent, normal));
+
+	float currentSample = sampleStep - sampleStep * noise;
+
+    // Skip on backfaces
+	currentSample += (tangentNdotL <= 0.0);
+
+	/*
+	From the PDF:
+	Trace from hit point to light direction and compute sum of dot products
+	between normal map and light direction.
+	If slope is bigger than 0, pixel is shadowed. If slope is also bigger
+	than previous maximal value, increase hardness of shadow.
+	*/
+
+	float result = 0;
+	float slope = -tangentNdotL;
+	float maxslope = 0.0;
+  for (uint i = 0; i < 1; i++)
+	{
+		normal = UnpackScaleNormal(tex2D(_BumpMap, nmsParam.uv + dir * currentSample), _BumpScale);
+		tangentNdotL = dot(lightDirTangent, normal);
+		slope = slope - tangentNdotL;
+		if (slope > maxslope)
+		{
+			result += hardness * (1.0-currentSample);
+		}
+		maxslope = max(maxslope, slope);
+		currentSample += sampleStep;
+    if (currentSample <= 1.0) {
+      break;
+    }
+	}
+
+	return result * sampleStep;
+}
+
+float NormalTangentShadow(float4 texcoords, half3 lightDirTS, float noise)
+{
+  float _HeightScale = _BumpShadowHeightScale;
+  float _ShadowHardness = _BumpShadowHardness;
+  NormalMapShadowsParam nms = InitNormalMapShadowsParam(texcoords);
+  nms.uv = texcoords;
+  return NormalMapShadows(lightDirTS, nms, noise, _HeightScale, _ShadowHardness);
+}
+#endif  // _BUMP_SHADOWS
+
 #endif