Fix #1156 Use infinity water depth

Fixes incorrect depth values when away from zero, and greatly simplifies
everything. Caution must be taken as infinity can cause issues.

Water depth sampling had to be moved to the fragment shader, as it had
artifacts possibly from interpolation.

Additionally, improved fading out of shallow SSS towards the end of
cascades.

crest/Assets/Crest/Crest/Scripts/LodData/LodDataMgrSeaFloorDepth.cs

@@ -17,13 +17,13 @@ namespace Crest
     public class LodDataMgrSeaFloorDepth : LodDataMgr
     {
         // NOTE: Must match CREST_OCEAN_DEPTH_BASELINE in OceanConstants.hlsl.
-        internal const float k_DepthBaseline = 1_000f;
+        internal const float k_DepthBaseline = Mathf.Infinity;
 
         public override string SimName => "SeaFloorDepth";
         protected override GraphicsFormat RequestedTextureFormat => Settings._allowVaryingWaterLevel ? GraphicsFormat.R32G32_SFloat : GraphicsFormat.R16_SFloat;
         protected override bool NeedToReadWriteTextureData => false;
-        // We want the clear colour to be the min terrain height (-1000m) in X, and sea level offset 0m in Y.
-        readonly static Color s_nullColor = Color.red * -k_DepthBaseline;
+        // Lowest possible scene height in X, and sea level offset 0m in Y.
+        readonly static Color s_nullColor = new Color(-k_DepthBaseline, 0, 0, 0);
         static Texture2DArray s_nullTexture;
         protected override Texture2DArray NullTexture => s_nullTexture;
 

crest/Assets/Crest/Crest/Scripts/LodData/OceanDepthCache.cs

@@ -212,9 +212,7 @@ bool InitObjects(bool updateComponents)
                 _camDepthCache.transform.parent = transform;
                 _camDepthCache.transform.localEulerAngles = 90f * Vector3.right;
                 _camDepthCache.orthographic = true;
-                _camDepthCache.clearFlags = CameraClearFlags.SolidColor;
-                // Clear to 'very deep'
-                _camDepthCache.backgroundColor = Color.white * LodDataMgrSeaFloorDepth.k_DepthBaseline;
+                _camDepthCache.clearFlags = CameraClearFlags.Depth;
                 _camDepthCache.enabled = false;
                 _camDepthCache.allowMSAA = false;
                 _camDepthCache.allowDynamicResolution = false;

crest/Assets/Crest/Crest/Scripts/LodData/Settings/SimSettingsAnimatedWaves.cs

@@ -35,8 +35,8 @@ public partial class SimSettingsAnimatedWaves : SimSettingsBase
         public float AttenuationInShallows => _attenuationInShallows;
 
         [Tooltip("Any water deeper than this will receive full wave strength. The lower the value, the less effective the depth cache will be at attenuating very large waves. Set to the maximum value (1,000) to disable.")]
-        [SerializeField, Range(1f, LodDataMgrSeaFloorDepth.k_DepthBaseline)]
-        float _shallowsMaxDepth = LodDataMgrSeaFloorDepth.k_DepthBaseline;
+        [SerializeField, Range(1f, 1000f)]
+        float _shallowsMaxDepth = 1000f;
         public float MaximumAttenuationDepth => _shallowsMaxDepth;
 
         public enum CollisionSources

crest/Assets/Crest/Crest/Shaders/Ocean.shader

@@ -364,7 +364,6 @@ Shader "Crest/Ocean"
 				// sample shape textures - always lerp between 2 LOD scales, so sample two textures
 				o.flow_shadow = half4(0.0, 0.0, 0.0, 0.0);
 
-				o.lodAlpha_worldXZUndisplaced_oceanDepth.w = CREST_OCEAN_DEPTH_BASELINE;
 				// Sample shape textures - always lerp between 2 LOD scales, so sample two textures
 
 				// Calculate sample weights. params.z allows shape to be faded out (used on last lod to support pop-less scale transitions)
@@ -410,11 +409,12 @@ Shader "Crest/Ocean"
 				// Data that needs to be sampled at the displaced position
 				half seaLevelOffset = 0.0;
 				o.seaLevelDerivs = 0.0;
+				half seaDepth = 0.0;
 				if (wt_smallerLod > 0.0001)
 				{
 					const float3 uv_slice_smallerLodDisp = WorldToUV(o.worldPos.xz, cascadeData0, _LD_SliceIndex);
 
-					SampleSeaDepth(_LD_TexArray_SeaFloorDepth, uv_slice_smallerLodDisp, wt_smallerLod, o.lodAlpha_worldXZUndisplaced_oceanDepth.w, seaLevelOffset, cascadeData0, o.seaLevelDerivs);
+					SampleSeaDepth(_LD_TexArray_SeaFloorDepth, uv_slice_smallerLodDisp, wt_smallerLod, seaDepth, seaLevelOffset, cascadeData0, o.seaLevelDerivs);
 
 					#if _SHADOWS_ON
 					// The minimum sampling weight is lower than others to fix shallow water colour popping.
@@ -428,7 +428,7 @@ Shader "Crest/Ocean"
 				{
 					const float3 uv_slice_biggerLodDisp = WorldToUV(o.worldPos.xz, cascadeData1, _LD_SliceIndex + 1);
 
-					SampleSeaDepth(_LD_TexArray_SeaFloorDepth, uv_slice_biggerLodDisp, wt_biggerLod, o.lodAlpha_worldXZUndisplaced_oceanDepth.w, seaLevelOffset, cascadeData1, o.seaLevelDerivs);
+					SampleSeaDepth(_LD_TexArray_SeaFloorDepth, uv_slice_biggerLodDisp, wt_biggerLod, seaDepth, seaLevelOffset, cascadeData1, o.seaLevelDerivs);
 
 					#if _SHADOWS_ON
 					// The minimum sampling weight is lower than others to fix shallow water colour popping.
@@ -526,10 +526,6 @@ Shader "Crest/Ocean"
 				half3 screenPos = input.screenPosXYW;
 				half2 uvDepth = screenPos.xy / screenPos.z;
 
-				#if _CLIPUNDERTERRAIN_ON
-				clip(input.lodAlpha_worldXZUndisplaced_oceanDepth.w + 2.0);
-				#endif
-
 				half3 view = normalize(_WorldSpaceCameraPos - input.worldPos);
 
 				// water surface depth, and underlying scene opaque surface depth
@@ -563,6 +559,8 @@ Shader "Crest/Ocean"
 				#if _ALBEDO_ON
 				half4 albedo = 0.0;
 				#endif
+
+				float seaDepth = 0.0;
 				if (wt_smallerLod > 0.001)
 				{
 					const float3 uv_slice_smallerLod = WorldToUV(positionXZWSUndisplaced, cascadeData0, _LD_SliceIndex);
@@ -575,6 +573,10 @@ Shader "Crest/Ocean"
 					#if _ALBEDO_ON
 					SampleAlbedo(_LD_TexArray_Albedo, uv_slice_smallerLod, wt_smallerLod, albedo);
 					#endif
+
+					#if defined(_SUBSURFACESHALLOWCOLOUR_ON) || defined(_CLIPUNDERTERRAIN_ON)
+					SampleSeaDepth(_LD_TexArray_SeaFloorDepth, uv_slice_smallerLod, wt_smallerLod, seaDepth);
+					#endif
 				}
 				if (wt_biggerLod > 0.001)
 				{
@@ -588,8 +590,24 @@ Shader "Crest/Ocean"
 					#if _ALBEDO_ON
 					SampleAlbedo(_LD_TexArray_Albedo, uv_slice_biggerLod, wt_biggerLod, albedo);
 					#endif
+
+					#if defined(_SUBSURFACESHALLOWCOLOUR_ON) || defined(_CLIPUNDERTERRAIN_ON)
+					SampleSeaDepth(_LD_TexArray_SeaFloorDepth, uv_slice_biggerLod, wt_biggerLod, seaDepth);
+					#endif
 				}
 
+#if _SUBSURFACESHALLOWCOLOUR_ON
+				seaDepth = min(_SubSurfaceDepthMax, seaDepth);
+				if (_LD_SliceIndex == ((uint)_SliceCount - 1))
+				{
+					seaDepth = lerp(_SubSurfaceDepthMax, seaDepth, wt_smallerLod);
+				}
+#endif
+
+				#if _CLIPUNDERTERRAIN_ON
+				clip(seaDepth + 2.0);
+				#endif
+
 #if _SUBSURFACESCATTERING_ON
 				// Extents need the default SSS to avoid popping and not being noticeably different.
 				if (_LD_SliceIndex == ((uint)_SliceCount - 1))
@@ -668,7 +686,7 @@ Shader "Crest/Ocean"
 				// Compute color of ocean - in-scattered light + refracted scene
 				half3 scatterCol = ScatterColour
 				(
-					input.lodAlpha_worldXZUndisplaced_oceanDepth.w,
+					seaDepth,
 					shadow.x,
 					sss,
 					view,
@@ -752,7 +770,7 @@ Shader "Crest/Ocean"
 					// global shadow value.
 					scatterCol = ScatterColour
 					(
-						input.lodAlpha_worldXZUndisplaced_oceanDepth.w,
+						seaDepth,
 						UnderwaterShadowSSS(_WorldSpaceCameraPos.xz),
 						sss,
 						view,

crest/Assets/Crest/Crest/Shaders/OceanConstants.hlsl

@@ -18,7 +18,8 @@
 
 // NOTE: Must match k_DepthBaseline in LodDataMgrSeaFloorDepth.cs.
 // Bias ocean floor depth so that default (0) values in texture are not interpreted as shallow and generating foam everywhere
-#define CREST_OCEAN_DEPTH_BASELINE 1000.0
+#define CREST_OCEAN_DEPTH_BASELINE 1.#INF
+#define CREST_MAXIMUM_ATTENUATION_DEPTH 1000.0
 
 // Soft shadows is red, hard shadows is green.
 #define CREST_SHADOW_INDEX_SOFT 0

crest/Assets/Crest/Crest/Shaders/OceanHelpersNew.hlsl

@@ -126,21 +126,20 @@ void SampleSeaDepth(in Texture2DArray i_oceanDepthSampler, in float3 i_uv_slice,
 {
 	const half2 terrainHeight_seaLevelOffset = i_oceanDepthSampler.SampleLevel(LODData_linear_clamp_sampler, i_uv_slice.xyz, 0.0).xy;
 	const half waterDepth = _OceanCenterPosWorld.y - terrainHeight_seaLevelOffset.x + terrainHeight_seaLevelOffset.y;
-	io_oceanDepth += i_wt * (waterDepth - CREST_OCEAN_DEPTH_BASELINE);
+	io_oceanDepth += i_wt * waterDepth;
 }
 
 void SampleSingleSeaDepth(Texture2DArray i_oceanDepthSampler, float3 i_uv_slice, inout half io_oceanDepth, inout half io_seaLevelOffset)
 {
 	const half2 terrainHeight_seaLevelOffset = i_oceanDepthSampler.SampleLevel(LODData_linear_clamp_sampler, i_uv_slice, 0.0).xy;
-	const half waterDepth = _OceanCenterPosWorld.y - terrainHeight_seaLevelOffset.x + terrainHeight_seaLevelOffset.y;
-	io_oceanDepth = waterDepth - CREST_OCEAN_DEPTH_BASELINE;
+	io_oceanDepth = _OceanCenterPosWorld.y - terrainHeight_seaLevelOffset.x + terrainHeight_seaLevelOffset.y;
 	io_seaLevelOffset = terrainHeight_seaLevelOffset.y;
 }
 
 void SampleSeaDepth(in Texture2DArray i_oceanDepthSampler, in float3 i_uv_slice, in float i_wt, inout half io_oceanDepth, inout half io_seaLevelOffset, const CascadeParams i_cascadeParams, inout float2 io_seaLevelDerivs)
 {
 	const half2 terrainHeight_seaLevelOffset = i_oceanDepthSampler.SampleLevel( LODData_linear_clamp_sampler, i_uv_slice, 0.0 ).xy;
-	io_oceanDepth += i_wt * (_OceanCenterPosWorld.y - terrainHeight_seaLevelOffset.x + terrainHeight_seaLevelOffset.y - CREST_OCEAN_DEPTH_BASELINE);
+	io_oceanDepth += i_wt * (_OceanCenterPosWorld.y - terrainHeight_seaLevelOffset.x + terrainHeight_seaLevelOffset.y);
 	io_seaLevelOffset += i_wt * terrainHeight_seaLevelOffset.y;
 
 	{

crest/Assets/Crest/Crest/Shaders/OceanInputs/AnimWavesSpectrum.shader

@@ -47,7 +47,7 @@ Shader "Crest/Inputs/Shape Waves/Sample Spectrum"
 			const half depth = _OceanCenterPosWorld.y - terrainHeight_seaLevelOffset.x + terrainHeight_seaLevelOffset.y;
 			// Attenuate if depth is less than half of the average wavelength.
 			half weight = saturate(2.0 * depth / _AverageWavelength);
-			if (_MaximumAttenuationDepth < CREST_OCEAN_DEPTH_BASELINE)
+			if (_MaximumAttenuationDepth < CREST_MAXIMUM_ATTENUATION_DEPTH)
 			{
 				weight = lerp(weight, 1.0, saturate(depth / _MaximumAttenuationDepth));
 			}

crest/Assets/Crest/Crest/Shaders/OceanInputs/Resources/AnimWavesGerstner.shader

@@ -77,7 +77,7 @@ Shader "Hidden/Crest/Inputs/Animated Waves/Gerstner Global"
 					_LD_TexArray_SeaFloorDepth.SampleLevel(LODData_linear_clamp_sampler, float3(input.uv_uvWaves.xy, _LD_SliceIndex), 0.0).xy;
 				const half depth = _OceanCenterPosWorld.y - terrainHeight_seaLevelOffset.x + terrainHeight_seaLevelOffset.y;
 				half depth_wt = saturate(2.0 * depth / _AverageWavelength);
-				if (_MaximumAttenuationDepth < CREST_OCEAN_DEPTH_BASELINE)
+				if (_MaximumAttenuationDepth < CREST_MAXIMUM_ATTENUATION_DEPTH)
 				{
 					depth_wt = lerp(depth_wt, 1.0, saturate(depth / _MaximumAttenuationDepth));
 				}

crest/Assets/Crest/Crest/Shaders/OceanInputs/Resources/AnimWavesGerstnerGeometry.shader

@@ -113,7 +113,7 @@ Shader "Crest/Inputs/Animated Waves/Gerstner Geometry"
                 const half2 terrainHeight_seaLevelOffset = _LD_TexArray_SeaFloorDepth.SampleLevel(LODData_linear_clamp_sampler, input.uv_slice, 0.0).xy;
                 const half depth = _OceanCenterPosWorld.y - terrainHeight_seaLevelOffset.x + terrainHeight_seaLevelOffset.y;
                 half depth_wt = saturate(2.0 * depth / _AverageWavelength);
-                if (_MaximumAttenuationDepth < CREST_OCEAN_DEPTH_BASELINE)
+                if (_MaximumAttenuationDepth < CREST_MAXIMUM_ATTENUATION_DEPTH)
                 {
                     depth_wt = lerp(depth_wt, 1.0, saturate(depth / _MaximumAttenuationDepth));
                 }

crest/Assets/Crest/Crest/Shaders/Underwater/UnderwaterCurtain.shader

@@ -199,7 +199,7 @@ Shader "Crest/Underwater Curtain"
 				const half shadow = 1.0;
 				const half sss = 0.0;
 
-				half seaFloorDepth = CREST_OCEAN_DEPTH_BASELINE;
+				half seaFloorDepth = 0.0;
 #if _SUBSURFACESHALLOWCOLOUR_ON
 				{
 					// compute scatter colour from cam pos. two scenarios this can be called:

crest/Assets/Crest/Crest/Shaders/Underwater/UnderwaterEffectShared.hlsl

@@ -197,7 +197,7 @@ half3 ApplyUnderwaterEffect
 		}
 #endif // _SHADOWS_ON
 
-		half seaFloorDepth = CREST_OCEAN_DEPTH_BASELINE;
+		half seaFloorDepth = 0.0;
 #if _SUBSURFACESHALLOWCOLOUR_ON
 		{
 			// compute scatter colour from cam pos. two scenarios this can be called: