From 3a618bb1122104692d0251639fd653b8a92102f6 Mon Sep 17 00:00:00 2001
From: Harvey Fong <harvey@oomer.org>
Date: Fri, 1 Aug 2025 08:13:43 -0600
Subject: [PATCH] added best bbox calc using instance world space xforms to do
 zoomextents

---
 vmax2bella.cpp | 44 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

diff --git a/vmax2bella.cpp b/vmax2bella.cpp
index 4ec0ef7..1331971 100644
--- a/vmax2bella.cpp
+++ b/vmax2bella.cpp
@@ -171,6 +171,7 @@ The 't' field in the snapshot's 's.id' dictionary indicates the type of snapshot
 */
 
 #include <iostream> // For input/output operations (cout, cin, etc.)
+#include <limits>   // For std::numeric_limits
 
 // Bella SDK includes - external libraries for 3D rendering
 #include "../bella_engine_sdk/src/bella_sdk/bella_scene.h" // For creating and manipulating 3D scenes in Bella
@@ -352,7 +353,7 @@ int DL_main(dl::Args& args) {
         std::vector<std::vector<oom::vmax::RGBA>> vmaxPalettes; // one palette per model
         std::vector<std::array<oom::vmax::Material, 8>> vmaxMaterials; // one material per model
 
-        oom::bella::defaultScene2025(belScene); // create the basic scene elements in Bella
+        //oom::bella::defaultScene2025(belScene); // create the basic scene elements in Bella
         
         // Loop over each model defined in scene.json and process the first instance 
         // This will be out canonical models, not instances
@@ -483,6 +484,47 @@ int DL_main(dl::Args& args) {
             }
         }
 
+        // Initialize bbox to "inverted infinity" so first point will always expand it
+        dl::Aabb sceneBbox;
+        sceneBbox.min = dl::Pos3::make(std::numeric_limits<double>::max(), 
+                                       std::numeric_limits<double>::max(), 
+                                       std::numeric_limits<double>::max());
+        sceneBbox.max = dl::Pos3::make(std::numeric_limits<double>::lowest(), 
+                                       std::numeric_limits<double>::lowest(), 
+                                       std::numeric_limits<double>::lowest());
+        int voxelCount = 0;
+
+        //  
+        auto worldPaths = belScene.world().paths(); // Scene Tree Loop
+        for ( auto eachPath : worldPaths )
+        {
+            auto eachLeaf = eachPath.leaf();  
+            if ( !eachLeaf.isTypeOf( "instancer" ) )
+                continue;            
+            voxelCount++;
+
+            auto instances = eachLeaf["steps"][0]["instances"].asBufferT<dl::Mat4f>(); // just need count
+            for (dl::UInt i = 0; i < instances.count; ++i) {
+                // Since we are dealing with 1x1x1 voxels
+                // approximate by using center of voxel instance instead of 8 corners
+                // for bbox calculation
+                auto instanceXform = eachPath.transform(0.0,i); // feed InstanceIdx
+                auto instancePos = dl::math::translation(instanceXform); // Extract translation directly
+                
+                // No branch - always expand (faster for large instance counts)
+                if (instancePos.x < sceneBbox.min.x) sceneBbox.min.x = instancePos.x;
+                if (instancePos.y < sceneBbox.min.y) sceneBbox.min.y = instancePos.y;
+                if (instancePos.z < sceneBbox.min.z) sceneBbox.min.z = instancePos.z;
+                if (instancePos.x > sceneBbox.max.x) sceneBbox.max.x = instancePos.x;
+                if (instancePos.y > sceneBbox.max.y) sceneBbox.max.y = instancePos.y;
+                if (instancePos.z > sceneBbox.max.z) sceneBbox.max.z = instancePos.z;
+            }
+        }
+
+        auto center = ( sceneBbox.min.v3 + sceneBbox.max.v3 ) * 0.5;
+        auto radius =dl::math::norm( sceneBbox.max - sceneBbox.min ) * 0.5;
+        dl::bella_sdk::zoomExtents(belScene.cameraPath(), dl::Vec3{center.x, center.y, center.z}, radius);
+
         // Write Bella File .bsz=compressed .bsa=ascii .bsx=binary
         belScene.write(bszName.buf());
     }