Add CreationState to fill in lightdef lookup start.

src/ObjLoading/Game/IW4/LightDef/LightDefAssetCreationStateIW4.cpp

@@ -0,0 +1,37 @@
+#include "LightDefAssetCreationStateIW4.h"
+
+#include "Utils/Logging/Log.h"
+
+using namespace IW4;
+
+LightDefAssetCreationState::LightDefAssetCreationState()
+    : m_lmap_pixels_used_for_falloff(0)
+{
+}
+
+void LightDefAssetCreationState::SetLightDefLookupStart(GfxLightDef* lightDef, AssetCreationContext& context)
+{
+    const auto* image = lightDef->attenuation.image;
+    if (!image)
+        return;
+
+    // We need the actual image to determine the width, so force load it, if it is a reference
+    if (image->name && image->name[0] == ',')
+    {
+        const auto forceLoadedImage = context.ForceLoadDependency<AssetImage>(&image->name[1]);
+        if (!forceLoadedImage)
+            return;
+
+        image = forceLoadedImage->Asset();
+    }
+
+    const int newLmapUsage = image->width + 2;
+    if (m_lmap_pixels_used_for_falloff + newLmapUsage > MAX_LMAP_USAGE)
+    {
+        con::error(
+            "Total pixel width of all attenuation textures plus 2 border pixels is {} > {}", m_lmap_pixels_used_for_falloff + newLmapUsage, MAX_LMAP_USAGE);
+    }
+
+    lightDef->lmapLookupStart = m_lmap_pixels_used_for_falloff + 1;
+    m_lmap_pixels_used_for_falloff += newLmapUsage;
+}