Testing multiple MipMap/TexelDensity solutions

Runtime/Shaders/MipMaps.shader

@@ -0,0 +1,75 @@
+// Ref: https://developer.nvidia.com/gpugems/gpugems2/part-iii-high-quality-rendering/chapter-28-mipmap-level-measurement
+// https://github.com/jintiao/MipmapLevel/blob/master/Assets/MipmapColor.shader
+
+Shader "Hidden/RS/MipMaps"
+{
+    SubShader
+    {
+        Tags { "RenderType" = "Opaque" }
+        LOD 100
+
+        Pass
+        {
+            CGPROGRAM
+            #pragma vertex vert
+            #pragma fragment frag
+
+            #include "UnityCG.cginc"
+            #include "RSUtilsCG.cginc"
+
+            struct appdata
+            {
+                float4 vertex : POSITION;
+                float2 uv : TEXCOORD0;
+            };
+
+            struct v2f
+            {
+                float2 uv : TEXCOORD0;
+                float2 uvmip : TEXCOORD1;
+                float4 vertex : SV_POSITION;
+            };
+
+            sampler2D _MainTex;
+            float4 _MainTex_ST;
+            float4 _MainTex_TexelSize;
+            float4 _MipMapColors[15]; // max mipmaps = 1 + floor(log2(maxTexSize))
+            int _Max;
+
+            v2f vert(appdata v)
+            {
+                v2f o;
+                o.vertex = UnityObjectToClipPos(v.vertex);
+                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
+
+				int mips = RS_MipCount(_MainTex_TexelSize);
+				float2 mipuv = v.uv * (_MainTex_TexelSize.zw / mips);
+				o.uvmip = TRANSFORM_TEX(mipuv, _MainTex);
+
+                return o;
+            }
+
+            fixed4 frag(v2f i) : SV_Target
+            {
+                int mipLevels = 1 + floor(log2(max(_MainTex_TexelSize.z, _MainTex_TexelSize.w)));
+
+                // int m = RS_MipMap(i.uvmip, _MainTex_TexelSize);
+                int m = RS_M(i.uvmip, _MainTex_TexelSize);
+                // int m = RS_Mip(i.uvmip, _MainTex_TexelSize, mipLevels);
+                // m = clamp(m, 0, _Max);
+
+                // m = RS_Remap(m, 0, 15, 0, _Max);
+
+                fixed4 mip = _MipMapColors[m];
+
+                fixed4 col = tex2D(_MainTex, i.uv);
+                fixed4 res;
+                res.rgb = lerp(col.rgb, mip.rgb, mip.a);
+                res.a = col.a;
+
+                return res;
+            }
+            ENDCG
+        }
+    }
+}

Runtime/Shaders/MipMaps.shader.meta

@@ -0,0 +1,10 @@
+fileFormatVersion: 2
+guid: 19d63524eb012af4e8e086121f546128
+ShaderImporter:
+  externalObjects: {}
+  defaultTextures: []
+  nonModifiableTextures: []
+  preprocessorOverride: 0
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Runtime/Shaders/RSUtilsCG.cginc

@@ -2,7 +2,7 @@
 #define RS_UTILS_CG_INCLUDED
 
 // https://www.ronja-tutorials.com/post/010-triplanar-mapping/
-fixed4 SampleTriPlanar(sampler2D tex, float4 tex_ST, float3 position, float3 normal, float sharpness)
+fixed4 RS_TriPlanar(sampler2D tex, float4 tex_ST, float3 position, float3 normal, float sharpness)
 {
 	//calculate UV coordinates for three projections
 	float2 uv_front = TRANSFORM_TEX(position.xy, tex);
@@ -34,4 +34,65 @@ fixed4 SampleTriPlanar(sampler2D tex, float4 tex_ST, float3 position, float3 nor
 	return col;
 }
 
+float RS_Remap(float value, float oldMin, float oldMax, float newMin, float newMax)
+{
+	return (newMin + (value - oldMin) * (newMax - newMin) / (oldMax - oldMin));
+}
+
+int RS_MipCount(float4 texelSize)
+{
+	int m = max(texelSize.z, texelSize.w);
+	int mip = 1 + floor(log2(m));
+
+	return mip;
+}
+
+// https://github.com/jintiao/MipmapLevel/blob/master/Assets/MipmapColor.shader
+int RS_MipMap(float2 uv, float4 texelSize)
+{
+	// Mipmap calculation.
+	float2 muv = uv * texelSize.zw;
+	float2 dx = ddx(muv);
+	float2 dy = ddy(muv);
+
+//#if 0
+//	float rho = max(sqrt(dot(dx, dx)), sqrt(dot(dy, dy)));
+//	float lambda = log2(rho);
+//#else
+	float rho = max(dot(dx, dx), dot(dy, dy));
+	float lambda = 0.5 * log2(rho);
+//#endif
+
+	return max(int(lambda + 0.5), 0);
+}
+
+float RS_Mip(float2 uv, float4 texelSize, int mipLevels)
+{
+	float2 muv = uv * texelSize.zw;
+
+	float2 derivX = ddx(muv);
+	float2 derivY = ddy(muv);
+
+	float delta_max_sqr = max(dot(derivX, derivX), dot(derivY, derivY));
+	float mip = 0.5 * log2(delta_max_sqr) * mipLevels;
+	
+	return mip;
+}
+
+// https://gamedev.stackexchange.com/questions/28401/detect-mip-mapping-level-in-the-shader
+float RS_M(float2 uv, float4 texelSize)
+{
+	float2 dx = ddx(uv * texelSize.zw);
+	float2 dy = ddy(uv * texelSize.zw);
+	float d = max(dot(dx, dx), dot(dy, dy));
+
+	// Clamp the value to the max mip level counts
+	const float rangeClamp = pow(2.0, (RS_MipCount(texelSize) - 1) * 2.0);
+	d = clamp(d, 1.0, rangeClamp);
+
+	float mipLevel = 0.5 * log2(d);
+	mipLevel = floor(mipLevel);
+
+	return mipLevel;
+}
 #endif

Runtime/Shaders/TexelDensityChecker.shader

@@ -0,0 +1,64 @@
+// Ref: https://aras-p.info/blog/2011/05/03/a-way-to-visualize-mip-levels/
+
+Shader "Hidden/RS/TexelDensityChecker"
+{
+	SubShader
+	{
+		Tags { "RenderType"="Opaque" }
+		LOD 100
+
+		Pass
+		{
+			CGPROGRAM
+			#pragma vertex vert
+			#pragma fragment frag
+
+			#include "UnityCG.cginc"
+			#include "RSPropertiesCG.cginc"
+			#include "RSUtilsCG.cginc"
+
+			struct appdata
+			{
+				float4 vertex : POSITION;
+				float2 uv : TEXCOORD0;
+			};
+
+			struct v2f
+			{
+				float2 uv : TEXCOORD0;
+				float2 uvmip : TEXCOORD1;
+				float4 vertex : SV_POSITION;
+			};
+
+			sampler2D _MainTex;
+			float4 _MainTex_ST;
+			float4 _MainTex_TexelSize;
+
+			v2f vert (appdata v)
+			{
+				v2f o;
+				o.vertex = UnityObjectToClipPos(v.vertex);
+				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
+
+				int mips = RS_MipCount(_MainTex_TexelSize);
+				float2 mipuv = v.uv * (_MainTex_TexelSize.zw / mips);
+				o.uvmip = TRANSFORM_TEX(mipuv, _MainTex);
+
+				return o;
+			}
+
+			fixed4 frag(v2f i) : SV_Target
+			{
+				fixed4 col = tex2D(_MainTex, i.uv);
+				fixed4 mip = tex2D(_RS_Texture, i.uvmip);
+
+				fixed4 res;
+				res.rgb = lerp(col.rgb, mip.rgb, mip.a);
+				res.a = col.a;
+
+				return res;
+			}
+			ENDCG
+		}
+	}
+}

Runtime/Shaders/TexelDensityChecker.shader.meta

@@ -0,0 +1,10 @@
+fileFormatVersion: 2
+guid: 83a3ee0da908c7542be7a089c047d28f
+ShaderImporter:
+  externalObjects: {}
+  defaultTextures: []
+  nonModifiableTextures: []
+  preprocessorOverride: 0
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Runtime/Shaders/TriPlanarSurface.shader

@@ -23,7 +23,7 @@ Shader "Hidden/RS/TriPlanarLit"
 
         void surf (Input IN, inout SurfaceOutputStandard o)
         {
-            fixed4 c = SampleTriPlanar(_RS_Texture, _RS_Texture_ST, IN.worldPos, IN.worldNormal, _RS_Sharpness);
+            fixed4 c = RS_TriPlanar(_RS_Texture, _RS_Texture_ST, IN.worldPos, IN.worldNormal, _RS_Sharpness);
 
             o.Albedo = c * _RS_Color;
             o.Metallic = _RS_Metallic;

Runtime/Shaders/TriPlanarUnlit.shader

@@ -38,7 +38,7 @@ Shader "Hidden/RS/TriPlanarUnlit"
 
 			fixed4 frag(v2f i) : SV_Target
 			{
-				fixed4 c = SampleTriPlanar(_RS_Texture, _RS_Texture_ST, i.worldPos, i.normal, _RS_Sharpness);
+				fixed4 c = RS_TriPlanar(_RS_Texture, _RS_Texture_ST, i.worldPos, i.normal, _RS_Sharpness);
 				c *= _RS_Color;
 	            return c;
 			}