fix(export): Area light's range value is exported accurately in the E…

…ditor (as shown in the inspector). (atteneder#106)

* fix: Light.areaSize is not available in builds, so assume default values.

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Compiler errors when safe mode (`GLTFAST_SAFE` scripting define) is enabled.
 - Compiler error with High Definition Render Pipeline version 17 (2023.3)
 - Removed usage of obsolete APIs in High Definition Render Pipeline version 17 (2023.3)
+- (Export) Area light's range value is exported accurately (as shown in the inspector).
 
 ## [6.2.0] - 2024-01-29
 

Runtime/Scripts/Export/GltfWriter.cs

@@ -234,19 +234,16 @@ public bool AddLight(Light uLight, out int lightId)
                 name = uLight.name
             };
 
+            var renderPipeline = RenderPipelineUtils.RenderPipeline;
+
             var lightType = uLight.type;
 
-            var renderPipeline = RenderPipelineUtils.RenderPipeline;
 #if USING_HDRP
             HDAdditionalLightData lightHd = null;
+
             if (renderPipeline == RenderPipeline.HighDefinition) {
                 lightHd = uLight.gameObject.GetComponent<HDAdditionalLightData>();
-#if !UNITY_2023_2_OR_NEWER
-                // For newer HDRP versions, the generic `uLight.type` works just fine
-                if (lightHd!=null && lightHd.type == HDLightType.Area) {
-                    lightType = LightType.Rectangle;
-                }
-#endif
+                lightType = lightHd?.TryGetLightType() ?? lightType;
             }
 #endif
 
@@ -279,7 +276,7 @@ public bool AddLight(Light uLight, out int lightId)
             }
 
             light.LightColor = uLight.color.linear;
-            light.range = uLight.range;
+            light.range = GetLightRange(uLight, lightType);
 
             switch (renderPipeline)
             {
@@ -356,6 +353,48 @@ float GetIntensity(LightUnit unit) {
             return true;
         }
 
+        /// <summary>
+        /// Retrieves the light's range.
+        /// In Unity 2023.1 and older `Light.range` would return what now is <see cref="Light.dilatedRange"/>, which is
+        /// the range extended by a certain area light size factor. This method removes that addition in that case to
+        /// get the original value that's shown in the inspector.
+        /// </summary>
+        /// <param name="light">Unity Light</param>
+        /// <param name="lightType">Actual light type (might differ from light.type in HDRP).</param>
+        /// <returns>The light's range.</returns>
+        static float GetLightRange(Light light, LightType lightType)
+        {
+#if UNITY_2023_2_OR_NEWER
+            return light.range;
+#else
+            var range = light.range;
+            switch (lightType)
+            {
+#if !USING_HDRP // And, of course, it behaves correctly in the particular case HDRP+Rectangle.
+                case LightType.Rectangle:
+#if UNITY_EDITOR
+                    var longestSide = light.areaSize.magnitude;
+#else
+                    // At runtime, assume default magnitude(vec2(1,1))
+                    var longestSide = 1.4142135624f;
+#endif
+                    range -= longestSide * .5f;
+                    break;
+#endif // !USING_HDRP
+                case LightType.Disc:
+#if UNITY_EDITOR
+                    var radius = light.areaSize.x;
+#else
+                    // At runtime, assume default
+                    const float radius = 1f;
+#endif
+                    range -= radius * .5f;
+                    break;
+            }
+            return range;
+#endif
+        }
+
         /// <inheritdoc />
         public void AddCameraToNode(int nodeId, int cameraId)
         {

Runtime/Scripts/Export/HDAdditionalLightDataExtensions.cs

@@ -0,0 +1,39 @@
+// SPDX-FileCopyrightText: 2024 Unity Technologies and the glTFast authors
+// SPDX-License-Identifier: Apache-2.0
+
+#if USING_HDRP && !UNITY_2023_2_OR_NEWER
+
+using UnityEngine;
+using UnityEngine.Rendering.HighDefinition;
+
+namespace GLTFast.Export
+{
+    static class HDAdditionalLightDataExtensions
+    {
+        /// <summary>
+        /// In older HDRP versions Light.type may not reflect the actual light type.
+        /// To get the actual light type, the HDAdditionalLightData component has to be queried.
+        /// </summary>
+        /// <param name="lightHd">HDRP specific light component.</param>
+        /// <returns>The HDRP specific light type or null otherwise.</returns>
+        public static LightType? TryGetLightType(this HDAdditionalLightData lightHd)
+        {
+            switch (lightHd.type)
+            {
+                case HDLightType.Area:
+                    switch (lightHd.areaLightShape)
+                    {
+                        case AreaLightShape.Rectangle:
+                            return LightType.Rectangle;
+                        case AreaLightShape.Tube:
+                        case AreaLightShape.Disc:
+                        default:
+                            return LightType.Disc;
+                    }
+            }
+
+            return null;
+        }
+    }
+}
+#endif