Particles not rendering correctly when fog is enabled.

Question

Hello!

I have a particle system representing snow, but many of the particles are being rendered as black. Fog is enabled, and the particles with more fog between them and the camera suffer from this problem - particles close to the camera are less affected by the fog, and render correctly. All particles render correctly as soon as fog is disabled.

Has anyone come across this problem before, and can it be fixed? It seems to make effective snow scenes all but impossible.

Answer 1

Best Answer

Answer by Eric5h5 · Sep 22, 2011 at 01:26 PM

Presumably the shader you're using has Fog { Color (0,0,0,0) } in it; use a different shader or modify the shader you're using so it doesn't have that.

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triangle4studios · Sep 03, 2020 at 09:05 PM 0

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This answer is useless to the community. Not to be rude, but you gave absolutely no info and to people who are not well versed with shading language, how to ADD this to the shader is completely obscure and non-obvious. By default in SRP particle shaders DO NOT support fog.

BenWiller1989 · Sep 04, 2020 at 05:47 PM 0

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Well, I answered this already, don't know why they post it over and over again. Particles are rendered in accordance to the material shader you use. Just click on any material you find, and observe it in the inspector. There on the top you will see the shader with a drop down. Open that and change the shader of that material to "particles/Priority Addictive (soft)" and assign this material to the particle system material slot under "Renderer/$$anonymous$$aterial". Now you can see it in the fog. That's all. Play around with it.

Answer 2

I've got the same problem with the "Heat Distortion" particle prefab. Which use the "Particles/Standart Unlit" shader. The solution was to download the "Built in shaders" and create a slightly modified version of the original one. I just replaced the line " #include "UnityStandardParticles.cginc" " with the content of that file and commented this line out: " UNITY_APPLY_FOG_COLOR(IN.fogCoord, result, fixed4(0,0,0,0)); ". Works...so far.

 // Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)
 
 Shader "Particles/Standard Unlit 2"
 {
     Properties
     {
         _MainTex("Albedo", 2D) = "white" {}
         _Color("Color", Color) = (1,1,1,1)
 
         _Cutoff("Alpha Cutoff", Range(0.0, 1.0)) = 0.5
 
         _BumpScale("Scale", Float) = 1.0
         _BumpMap("Normal Map", 2D) = "bump" {}
 
         _EmissionColor("Color", Color) = (0,0,0)
         _EmissionMap("Emission", 2D) = "white" {}
 
         _DistortionStrength("Strength", Float) = 1.0
         _DistortionBlend("Blend", Range(0.0, 1.0)) = 0.5
 
         _SoftParticlesNearFadeDistance("Soft Particles Near Fade", Float) = 0.0
         _SoftParticlesFarFadeDistance("Soft Particles Far Fade", Float) = 1.0
         _CameraNearFadeDistance("Camera Near Fade", Float) = 1.0
         _CameraFarFadeDistance("Camera Far Fade", Float) = 2.0
 
         // Hidden properties
         [HideInInspector] _Mode ("__mode", Float) = 0.0
         [HideInInspector] _ColorMode ("__colormode", Float) = 0.0
         [HideInInspector] _FlipbookMode ("__flipbookmode", Float) = 0.0
         [HideInInspector] _LightingEnabled ("__lightingenabled", Float) = 0.0
         [HideInInspector] _DistortionEnabled ("__distortionenabled", Float) = 0.0
         [HideInInspector] _EmissionEnabled ("__emissionenabled", Float) = 0.0
         [HideInInspector] _BlendOp ("__blendop", Float) = 0.0
         [HideInInspector] _SrcBlend ("__src", Float) = 1.0
         [HideInInspector] _DstBlend ("__dst", Float) = 0.0
         [HideInInspector] _ZWrite ("__zw", Float) = 1.0
         [HideInInspector] _Cull ("__cull", Float) = 2.0
         [HideInInspector] _SoftParticlesEnabled ("__softparticlesenabled", Float) = 0.0
         [HideInInspector] _CameraFadingEnabled ("__camerafadingenabled", Float) = 0.0
         [HideInInspector] _SoftParticleFadeParams ("__softparticlefadeparams", Vector) = (0,0,0,0)
         [HideInInspector] _CameraFadeParams ("__camerafadeparams", Vector) = (0,0,0,0)
         [HideInInspector] _ColorAddSubDiff ("__coloraddsubdiff", Vector) = (0,0,0,0)
         [HideInInspector] _DistortionStrengthScaled ("__distortionstrengthscaled", Float) = 0.0
     }
 
     Category
     {
         SubShader
         {
             Tags { "RenderType"="Opaque" "IgnoreProjector"="True" "PreviewType"="Plane" "PerformanceChecks"="False" }
 
             BlendOp [_BlendOp]
             Blend [_SrcBlend] [_DstBlend]
             ZWrite [_ZWrite]
             Cull [_Cull]
             ColorMask RGB
 
             GrabPass
             {
                 Tags { "LightMode" = "Always" }
                 "_GrabTexture"
             }
 
             Pass
             {
                 Name "ShadowCaster"
                 Tags { "LightMode" = "ShadowCaster" }
 
                 BlendOp Add
                 Blend One Zero
                 ZWrite On
                 Cull Off
 
                 CGPROGRAM
                 #pragma target 2.5
 
                 #pragma shader_feature_local _ _ALPHATEST_ON _ALPHABLEND_ON _ALPHAPREMULTIPLY_ON _ALPHAMODULATE_ON
                 #pragma shader_feature_local_fragment _ _COLOROVERLAY_ON _COLORCOLOR_ON _COLORADDSUBDIFF_ON
                 #pragma shader_feature_local _REQUIRE_UV2
                 #pragma multi_compile_shadowcaster
                 #pragma multi_compile_instancing
                 #pragma instancing_options procedural:vertInstancingSetup
 
                 #pragma vertex vertParticleShadowCaster
                 #pragma fragment fragParticleShadowCaster
 
                 #include "UnityStandardParticleShadow.cginc"
                 ENDCG
             }
 
             Pass
             {
                 Name "SceneSelectionPass"
                 Tags { "LightMode" = "SceneSelectionPass" }
 
                 BlendOp Add
                 Blend One Zero
                 ZWrite On
                 Cull Off
 
                 CGPROGRAM
                 #pragma target 2.5
 
                 #pragma shader_feature_local_fragment _ALPHATEST_ON
                 #pragma shader_feature_local _REQUIRE_UV2
                 #pragma multi_compile_instancing
                 #pragma instancing_options procedural:vertInstancingSetup
 
                 #pragma vertex vertEditorPass
                 #pragma fragment fragSceneHighlightPass
 
                 #include "UnityStandardParticleEditor.cginc"
                 ENDCG
             }
 
             Pass
             {
                 Name "ScenePickingPass"
                 Tags{ "LightMode" = "Picking" }
 
                 BlendOp Add
                 Blend One Zero
                 ZWrite On
                 Cull Off
 
                 CGPROGRAM
                 #pragma target 2.5
 
                 #pragma shader_feature_local_fragment _ALPHATEST_ON
                 #pragma shader_feature_local _REQUIRE_UV2
                 #pragma multi_compile_instancing
                 #pragma instancing_options procedural:vertInstancingSetup
 
                 #pragma vertex vertEditorPass
                 #pragma fragment fragScenePickingPass
 
                 #include "UnityStandardParticleEditor.cginc"
                 ENDCG
             }
 
             Pass
             {
                 Tags { "LightMode"="ForwardBase" }
 
                 CGPROGRAM
                 #pragma multi_compile __ SOFTPARTICLES_ON
                 #pragma multi_compile_fog
                 #pragma target 2.5
 
                 #pragma shader_feature_local_fragment _ _ALPHATEST_ON _ALPHABLEND_ON _ALPHAPREMULTIPLY_ON _ALPHAMODULATE_ON
                 #pragma shader_feature_local_fragment _ _COLOROVERLAY_ON _COLORCOLOR_ON _COLORADDSUBDIFF_ON
                 #pragma shader_feature_local _NORMALMAP
                 #pragma shader_feature_fragment _EMISSION
                 #pragma shader_feature_local _FADING_ON
                 #pragma shader_feature_local _REQUIRE_UV2
                 #pragma shader_feature_local EFFECT_BUMP
 
                 #pragma vertex vertParticleUnlit
                 #pragma fragment fragParticleUnlit
                 #pragma multi_compile_instancing
                 #pragma instancing_options procedural:vertInstancingSetup
 
                 //#include "UnityStandardParticles.cginc"
                 #ifndef UNITY_STANDARD_PARTICLES_INCLUDED
 #define UNITY_STANDARD_PARTICLES_INCLUDED
 
 #if _REQUIRE_UV2
 #define _FLIPBOOK_BLENDING 1
 #endif
 
 #if EFFECT_BUMP
 #define _DISTORTION_ON 1
 #endif
 
 #include "UnityPBSLighting.cginc"
 #include "UnityStandardParticleInstancing.cginc"
 
 // Particles surface shader has a lot of variants in it, but some of those do not affect
 // code generation (i.e. don't have inpact on which Input/SurfaceOutput things are read or written into).
 // Surface shader analysis done during import time skips "completely identical" shader variants, so to
 // help this process we'll turn off some features that we know are not affecting the inputs/outputs.
 //
 // If you change the logic of what the below variants do, make sure to not regress code generation though,
 // e.g. compare full "show generated code" output of the surface shader before & after the change.
 #if defined(SHADER_TARGET_SURFACE_ANALYSIS)
     // All these only alter the color in various ways
     #undef _COLOROVERLAY_ON
     #undef _COLORCOLOR_ON
     #undef _COLORADDSUBDIFF_ON
     #undef _ALPHAMODULATE_ON
     #undef _ALPHATEST_ON
 
     // For inputs/outputs analysis SoftParticles and Fading are identical; so make sure to only keep one
     // of them ever defined.
     #if defined(SOFTPARTICLES_ON)
         #undef SOFTPARTICLES_ON
         #define _FADING_ON
     #endif
 #endif
 
 
 // Vertex shader input
 struct appdata_particles
 {
     float4 vertex : POSITION;
     float3 normal : NORMAL;
     fixed4 color : COLOR;
     #if defined(_FLIPBOOK_BLENDING) && !defined(UNITY_PARTICLE_INSTANCING_ENABLED)
     float4 texcoords : TEXCOORD0;
     float texcoordBlend : TEXCOORD1;
     #else
     float2 texcoords : TEXCOORD0;
     #endif
     #if defined(_NORMALMAP)
     float4 tangent : TANGENT;
     #endif
     UNITY_VERTEX_INPUT_INSTANCE_ID
 };
 
 // Surface shader input
 struct Input
 {
     float4 color : COLOR;
     float2 texcoord;
     #if defined(_FLIPBOOK_BLENDING)
     float3 texcoord2AndBlend;
     #endif
     #if defined(SOFTPARTICLES_ON) || defined(_FADING_ON)
     float4 projectedPosition;
     #endif
     #if _DISTORTION_ON
     float4 grabPassPosition;
     #endif
 };
 
 // Non-surface shader v2f structure
 struct VertexOutput
 {
     float4 vertex : SV_POSITION;
     float4 color : COLOR;
     UNITY_FOG_COORDS(0)
     float2 texcoord : TEXCOORD1;
     #if defined(_FLIPBOOK_BLENDING)
     float3 texcoord2AndBlend : TEXCOORD2;
     #endif
     #if defined(SOFTPARTICLES_ON) || defined(_FADING_ON)
     float4 projectedPosition : TEXCOORD3;
     #endif
     #if _DISTORTION_ON
     float4 grabPassPosition : TEXCOORD4;
     #endif
     UNITY_VERTEX_OUTPUT_STEREO
 
 };
 
 fixed4 readTexture(sampler2D tex, Input IN)
 {
     fixed4 color = tex2D (tex, IN.texcoord);
     #ifdef _FLIPBOOK_BLENDING
     fixed4 color2 = tex2D(tex, IN.texcoord2AndBlend.xy);
     color = lerp(color, color2, IN.texcoord2AndBlend.z);
     #endif
     return color;
 }
 
 fixed4 readTexture(sampler2D tex, VertexOutput IN)
 {
     fixed4 color = tex2D (tex, IN.texcoord);
     #ifdef _FLIPBOOK_BLENDING
     fixed4 color2 = tex2D(tex, IN.texcoord2AndBlend.xy);
     color = lerp(color, color2, IN.texcoord2AndBlend.z);
     #endif
     return color;
 }
 
 sampler2D _MainTex;
 float4 _MainTex_ST;
 half4 _Color;
 sampler2D _BumpMap;
 half _BumpScale;
 sampler2D _EmissionMap;
 half3 _EmissionColor;
 sampler2D _MetallicGlossMap;
 half _Metallic;
 half _Glossiness;
 UNITY_DECLARE_DEPTH_TEXTURE(_CameraDepthTexture);
 float4 _SoftParticleFadeParams;
 float4 _CameraFadeParams;
 half _Cutoff;
 
 #define SOFT_PARTICLE_NEAR_FADE _SoftParticleFadeParams.x
 #define SOFT_PARTICLE_INV_FADE_DISTANCE _SoftParticleFadeParams.y
 
 #define CAMERA_NEAR_FADE _CameraFadeParams.x
 #define CAMERA_INV_FADE_DISTANCE _CameraFadeParams.y
 
 #if _DISTORTION_ON
 sampler2D _GrabTexture;
 half _DistortionStrengthScaled;
 half _DistortionBlend;
 #endif
 
 #if defined (_COLORADDSUBDIFF_ON)
 half4 _ColorAddSubDiff;
 #endif
 
 #if defined(_COLORCOLOR_ON)
 half3 RGBtoHSV(half3 arg1)
 {
     half4 K = half4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
     half4 P = lerp(half4(arg1.bg, K.wz), half4(arg1.gb, K.xy), step(arg1.b, arg1.g));
     half4 Q = lerp(half4(P.xyw, arg1.r), half4(arg1.r, P.yzx), step(P.x, arg1.r));
     half D = Q.x - min(Q.w, Q.y);
     half E = 1e-4;
     return half3(abs(Q.z + (Q.w - Q.y) / (6.0 * D + E)), D / (Q.x + E), Q.x);
 }
 
 half3 HSVtoRGB(half3 arg1)
 {
     half4 K = half4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
     half3 P = abs(frac(arg1.xxx + K.xyz) * 6.0 - K.www);
     return arg1.z * lerp(K.xxx, saturate(P - K.xxx), arg1.y);
 }
 #endif
 
 // Color function
 #if defined(UNITY_PARTICLE_INSTANCING_ENABLED)
 #define vertColor(c) \
         vertInstancingColor(c);
 #else
 #define vertColor(c)
 #endif
 
 // Flipbook vertex function
 #if defined(UNITY_PARTICLE_INSTANCING_ENABLED)
     #if defined(_FLIPBOOK_BLENDING)
     #define vertTexcoord(v, o) \
         vertInstancingUVs(v.texcoords.xy, o.texcoord, o.texcoord2AndBlend);
     #else
     #define vertTexcoord(v, o) \
         vertInstancingUVs(v.texcoords.xy, o.texcoord); \
         o.texcoord = TRANSFORM_TEX(o.texcoord, _MainTex);
     #endif
 #else
     #if defined(_FLIPBOOK_BLENDING)
     #define vertTexcoord(v, o) \
         o.texcoord = v.texcoords.xy; \
         o.texcoord2AndBlend.xy = v.texcoords.zw; \
         o.texcoord2AndBlend.z = v.texcoordBlend;
     #else
     #define vertTexcoord(v, o) \
         o.texcoord = TRANSFORM_TEX(v.texcoords.xy, _MainTex);
     #endif
 #endif
 
 // Fading vertex function
 #if defined(SOFTPARTICLES_ON) || defined(_FADING_ON)
 #define vertFading(o) \
     o.projectedPosition = ComputeScreenPos (clipPosition); \
     COMPUTE_EYEDEPTH(o.projectedPosition.z);
 #else
 #define vertFading(o)
 #endif
 
 // Distortion vertex function
 #if _DISTORTION_ON
 #define vertDistortion(o) \
     o.grabPassPosition = ComputeGrabScreenPos (clipPosition);
 #else
 #define vertDistortion(o)
 #endif
 
 // Color blending fragment function
 #if defined(_COLOROVERLAY_ON)
 #define fragColorMode(i) \
     albedo.rgb = lerp(1 - 2 * (1 - albedo.rgb) * (1 - i.color.rgb), 2 * albedo.rgb * i.color.rgb, step(albedo.rgb, 0.5)); \
     albedo.a *= i.color.a;
 #elif defined(_COLORCOLOR_ON)
 #define fragColorMode(i) \
     half3 aHSL = RGBtoHSV(albedo.rgb); \
     half3 bHSL = RGBtoHSV(i.color.rgb); \
     half3 rHSL = fixed3(bHSL.x, bHSL.y, aHSL.z); \
     albedo = fixed4(HSVtoRGB(rHSL), albedo.a * i.color.a);
 #elif defined(_COLORADDSUBDIFF_ON)
 #define fragColorMode(i) \
     albedo.rgb = albedo.rgb + i.color.rgb * _ColorAddSubDiff.x; \
     albedo.rgb = lerp(albedo.rgb, abs(albedo.rgb), _ColorAddSubDiff.y); \
     albedo.a *= i.color.a;
 #else
 #define fragColorMode(i) \
     albedo *= i.color;
 #endif
 
 // Pre-multiplied alpha helper
 #if defined(_ALPHAPREMULTIPLY_ON)
 #define ALBEDO_MUL albedo
 #else
 #define ALBEDO_MUL albedo.a
 #endif
 
 // Soft particles fragment function
 #if defined(SOFTPARTICLES_ON) && defined(_FADING_ON)
 #define fragSoftParticles(i) \
     float softParticlesFade = 1.0f; \
     if (SOFT_PARTICLE_NEAR_FADE > 0.0 || SOFT_PARTICLE_INV_FADE_DISTANCE > 0.0) \
     { \
         float sceneZ = LinearEyeDepth (SAMPLE_DEPTH_TEXTURE_PROJ(_CameraDepthTexture, UNITY_PROJ_COORD(i.projectedPosition))); \
         softParticlesFade = saturate (SOFT_PARTICLE_INV_FADE_DISTANCE * ((sceneZ - SOFT_PARTICLE_NEAR_FADE) - i.projectedPosition.z)); \
         ALBEDO_MUL *= softParticlesFade; \
     }
 #else
 #define fragSoftParticles(i) \
     float softParticlesFade = 1.0f;
 #endif
 
 // Camera fading fragment function
 #if defined(_FADING_ON)
 #define fragCameraFading(i) \
     float cameraFade = saturate((i.projectedPosition.z - CAMERA_NEAR_FADE) * CAMERA_INV_FADE_DISTANCE); \
     ALBEDO_MUL *= cameraFade;
 #else
 #define fragCameraFading(i) \
     float cameraFade = 1.0f;
 #endif
 
 #if _DISTORTION_ON
 #define fragDistortion(i) \
     float4 grabPosUV = UNITY_PROJ_COORD(i.grabPassPosition); \
     grabPosUV.xy += normal.xy * _DistortionStrengthScaled * albedo.a; \
     half3 grabPass = tex2Dproj(_GrabTexture, grabPosUV).rgb; \
     albedo.rgb = lerp(grabPass, albedo.rgb, saturate(albedo.a - _DistortionBlend));
 #else
 #define fragDistortion(i)
 #endif
 
 void vert (inout appdata_particles v, out Input o)
 {
     UNITY_INITIALIZE_OUTPUT(Input, o);
     float4 clipPosition = UnityObjectToClipPos(v.vertex);
 
     vertColor(v.color);
     vertTexcoord(v, o);
     vertFading(o);
     vertDistortion(o);
 }
 
 void surf (Input IN, inout SurfaceOutputStandard o)
 {
     half4 albedo = readTexture (_MainTex, IN);
     albedo *= _Color;
 
     fragColorMode(IN);
     fragSoftParticles(IN);
     fragCameraFading(IN);
 
     #if defined(_METALLICGLOSSMAP)
     fixed2 metallicGloss = readTexture (_MetallicGlossMap, IN).ra * fixed2(1.0, _Glossiness);
     #else
     fixed2 metallicGloss = fixed2(_Metallic, _Glossiness);
     #endif
 
     #if defined(_NORMALMAP)
     float3 normal = normalize (UnpackScaleNormal (readTexture (_BumpMap, IN), _BumpScale));
     #else
     float3 normal = float3(0,0,1);
     #endif
 
     #if defined(_EMISSION)
     half3 emission = readTexture (_EmissionMap, IN).rgb * cameraFade * softParticlesFade;
     #else
     half3 emission = 0;
     #endif
 
     fragDistortion(IN);
 
     o.Albedo = albedo.rgb;
     #if defined(_NORMALMAP)
     o.Normal = normal;
     #endif
     o.Emission = emission * _EmissionColor;
     o.Metallic = metallicGloss.r;
     o.Smoothness = metallicGloss.g;
 
     #if defined(_ALPHABLEND_ON) || defined(_ALPHAPREMULTIPLY_ON) || defined(_ALPHAOVERLAY_ON)
     o.Alpha = albedo.a;
     #else
     o.Alpha = 1;
     #endif
 
     #if defined(_ALPHAMODULATE_ON)
     o.Albedo = lerp(half3(1.0, 1.0, 1.0), albedo.rgb, albedo.a);
     #endif
 
     #if defined(_ALPHATEST_ON)
     clip (albedo.a - _Cutoff + 0.0001);
     #endif
 }
 
 void vertParticleUnlit (appdata_particles v, out VertexOutput o)
 {
     UNITY_SETUP_INSTANCE_ID(v);
 
     UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
 
     float4 clipPosition = UnityObjectToClipPos(v.vertex);
     o.vertex = clipPosition;
     o.color = v.color;
 
     vertColor(o.color);
     vertTexcoord(v, o);
     vertFading(o);
     vertDistortion(o);
 
     UNITY_TRANSFER_FOG(o, o.vertex);
 }
 
 half4 fragParticleUnlit (VertexOutput IN) : SV_Target
 {
     half4 albedo = readTexture (_MainTex, IN);
     albedo *= _Color;
 
     fragColorMode(IN);
     fragSoftParticles(IN);
     fragCameraFading(IN);
 
     #if defined(_NORMALMAP)
     float3 normal = normalize (UnpackScaleNormal (readTexture (_BumpMap, IN), _BumpScale));
     #else
     float3 normal = float3(0,0,1);
     #endif
 
     #if defined(_EMISSION)
     half3 emission = readTexture (_EmissionMap, IN).rgb;
     #else
     half3 emission = 0;
     #endif
 
     fragDistortion(IN);
 
     half4 result = albedo;
 
     #if defined(_ALPHAMODULATE_ON)
     result.rgb = lerp(half3(1.0, 1.0, 1.0), albedo.rgb, albedo.a);
     #endif
 
     result.rgb += emission * _EmissionColor * cameraFade * softParticlesFade;
 
     #if !defined(_ALPHABLEND_ON) && !defined(_ALPHAPREMULTIPLY_ON) && !defined(_ALPHAOVERLAY_ON)
     result.a = 1;
     #endif
 
     #if defined(_ALPHATEST_ON)
     clip (albedo.a - _Cutoff + 0.0001);
     #endif
 
     //UNITY_APPLY_FOG_COLOR(IN.fogCoord, result, fixed4(0,0,0,0));
     return result;
 }
 
 #endif // UNITY_STANDARD_PARTICLES_INCLUDED
                 ENDCG
             }
         }
     }
 
     Fallback "VertexLit"
     CustomEditor "StandardParticlesShaderGUI"
 }

Answer 3

Answer by angelonit · Jan 18 at 04:30 PM

changed this-> UNITY_APPLY_FOG_COLOR(IN.fogCoord, result, fixed4(0, 0, 0, 0));

for this -> UNITY_APPLY_FOG_COLOR(IN.fogCoord, result, unity_FogColor);

The particles should become the color of the environmental fog (unity_FogColor) you have set in lighting tab instead of the default black (my particles are in "Fade" mode)

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Particles not rendering correctly when fog is enabled.

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