[VFX] Add shader formatting for Infinity and NaN in floats #259

Author: gabrieldelacruz

com.unity.render-pipelines.high-definition/Runtime/VFXGraph/Shaders/VFXDefines.hlsl

@@ -39,4 +39,7 @@
 // this is only necessary for the old VFXTarget pathway
 // it defines the macro used to access hybrid instanced properties
 // (new HDRP/URP Target pathway overrides the type so this is never used)
+#define VFX_INFINITY  (1.0f/0.0f)
+#define VFX_NAN       asfloat(~0u)
+
 #define UNITY_ACCESS_HYBRID_INSTANCED_PROP(name, type) name

com.unity.visualeffectgraph/Editor/Compiler/VFXShaderWriter.cs

@@ -61,30 +61,40 @@ public static string GetValueString(VFXValueType type, object value)
                     value = value.ToString().ToLower();
                     break;
                 case VFXValueType.Float:
-                    value = ((float)value).ToString("G9", CultureInfo.InvariantCulture);
+                    value = FormatFloat((float)value);
                     break;
                 case VFXValueType.Float2:
-                    value = $"({((Vector2)value).x.ToString("G9", CultureInfo.InvariantCulture)}, {((Vector2)value).y.ToString("G9", CultureInfo.InvariantCulture)})";
+                    value = $"({FormatFloat(((Vector2)value).x)}, {FormatFloat(((Vector2)value).y)})";
                     break;
                 case VFXValueType.Float3:
-                    value = $"({((Vector3)value).x.ToString("G9", CultureInfo.InvariantCulture)}, {((Vector3)value).y.ToString("G9", CultureInfo.InvariantCulture)}, {((Vector3)value).z.ToString("G9", CultureInfo.InvariantCulture)})";
+                    value = $"({FormatFloat(((Vector3)value).x)}, {FormatFloat(((Vector3)value).y)}, {FormatFloat(((Vector3)value).z)})";
                     break;
                 case VFXValueType.Float4:
-                    value = $"({((Vector4)value).x.ToString("G9", CultureInfo.InvariantCulture)}, {((Vector4)value).y.ToString("G9", CultureInfo.InvariantCulture)}, {((Vector4)value).z.ToString("G9", CultureInfo.InvariantCulture)}, {((Vector4)value).w.ToString("G9", CultureInfo.InvariantCulture)})";
+                    value = $"({FormatFloat(((Vector4)value).x)}, {FormatFloat(((Vector4)value).y)}, {FormatFloat(((Vector4)value).z)}, {FormatFloat(((Vector4)value).w)})";
                     break;
                 case VFXValueType.Matrix4x4:
                 {
                     var matrix = ((Matrix4x4)value).transpose;
                     value = "(";
                     for (int i = 0; i < 16; ++i)
-                        value += string.Format(CultureInfo.InvariantCulture, i == 15 ? "{0}" : "{0},", matrix[i].ToString("G9", CultureInfo.InvariantCulture));
+                        value += string.Format(CultureInfo.InvariantCulture, i == 15 ? "{0}" : "{0},", FormatFloat(matrix[i]));
                     value += ")";
                 }
                 break;
             }
             return string.Format(CultureInfo.InvariantCulture, format, VFXExpression.TypeToCode(type), value);
         }
 
+        private static string FormatFloat(float f)
+        {
+            if (float.IsInfinity(f))
+                return f > 0.0f ? "VFX_INFINITY" : "-VFX_INFINITY";
+            else if (float.IsNaN(f))
+                return "VFX_NAN";
+            else
+                return f.ToString("G9", CultureInfo.InvariantCulture);
+        }
+
         public static string GetMultilineWithPrefix(string str, string linePrefix)
         {
             if (linePrefix.Length == 0)

com.unity.visualeffectgraph/Editor/Models/Blocks/Implementations/Attribute/AttributeFromCurve.cs

@@ -387,10 +387,9 @@ public override IEnumerable<VFXNamedExpression> parameters
                 if (SampleMode == CurveSampleMode.BySpeed)
                 {
                     var speedRangeComponents = VFXOperatorUtility.ExtractComponents(speedRange).ToArray();
-                    // speedRange.y = 1 / (sign(speedRange.y - speedRange.y) * max(epsilon, abs(speedRange.y - speedRange.y))
+                    // speedRange.y = 1 / (speedRange.y - speedRange.x)
                     var speedRangeDelta = speedRangeComponents[1] - speedRangeComponents[0];
-                    var denom = new VFXExpressionSign(speedRangeDelta) * new VFXExpressionMax(VFXOperatorUtility.EpsilonExpression[VFXValueType.Float], new VFXExpressionAbs(speedRangeDelta));
-                    speedRangeComponents[1] = VFXOperatorUtility.OneExpression[VFXValueType.Float] / denom;
+                    speedRangeComponents[1] = VFXOperatorUtility.OneExpression[VFXValueType.Float] / speedRangeDelta;
                     yield return new VFXNamedExpression(new VFXExpressionCombine(speedRangeComponents), "SpeedRange");
                 }
             }

com.unity.visualeffectgraph/Shaders/ParticlePoints/Pass.template

@@ -25,7 +25,10 @@ VFX_VARYING_PS_INPUTS vert(uint id : SV_VertexID, vs_input i)
 	${VFXProcessBlocks}
 
 	if (!attributes.alive)
+	{
+		o.pos.x = VFX_NAN;
 		return o;
+	}
 
 	float3 vPos = attributes.position;
 	o.VFX_VARYING_POSCS = TransformPositionVFXToClip(vPos);

com.unity.visualeffectgraph/Shaders/VFXParticleCommon.template

@@ -75,6 +75,7 @@ if (index >= asuint(nbMax) - deadCount)
 #if USE_GEOMETRY_SHADER
 	return; // cull
 #else
+	o.pos.x = VFX_NAN;
 	return o; // cull
 #endif
 
@@ -88,7 +89,10 @@ ${VFXLoadAttributes}
 ${VFXLoadAttributes:{alive}}
 #if !HAS_STRIPS
 if (!attributes.alive)
+{
+	o.pos.x = VFX_NAN;
 	return o;
+}
 #endif
 
 ${VFXLoadAttributes:{(?!(alive))(\b\w)}}