perf(render): instance block geometry

Share source buffers across block placements and render nested content with GPU instance transforms.\n\nChunk silhouettes and compact mesh material data so large drawings stay under device buffer limits and remain responsive.

src/scene/entity.rs

@@ -1099,6 +1099,7 @@ impl Scene {
         .with_viewport(viewport);
         let mut hatch_block_memo = std::collections::HashMap::new();
         let mut models = Vec::new();
+        let mut hatch_sources = rustc_hash::FxHashMap::default();
         graph.walk_root(
             self.render_scene_root(layout_block),
             |entity, context| {
@@ -1185,6 +1186,35 @@ impl Scene {
                 if tint_selected && self.selected.contains(&context.root_handle) {
                     model.color = [0.15, 0.55, 1.00, model.color[3]];
                 }
+                let matrix = &context.transform.matrix.m;
+                let linear = [
+                    matrix[0][0].to_bits(), matrix[0][1].to_bits(), matrix[0][2].to_bits(),
+                    matrix[1][0].to_bits(), matrix[1][1].to_bits(), matrix[1][2].to_bits(),
+                    matrix[2][0].to_bits(), matrix[2][1].to_bits(), matrix[2][2].to_bits(),
+                ];
+                let key = (
+                    source_hatch.common.handle.value(),
+                    linear,
+                    model
+                        .boundary
+                        .iter()
+                        .flat_map(|point| point.map(f32::to_bits))
+                        .collect::<Vec<_>>(),
+                    model.color.map(f32::to_bits),
+                    model.angle_offset.to_bits(),
+                    model.scale.to_bits(),
+                    model.line_weight_px.to_bits(),
+                    model.aci,
+                );
+                let source_id = *hatch_sources
+                    .entry(key)
+                    .or_insert_with(crate::scene::model::instance_model::next_source_id);
+                model.render_instance = Some(
+                    crate::scene::model::instance_model::RenderInstance {
+                        source_id,
+                        translation: [matrix[0][3], matrix[1][3], matrix[2][3]],
+                    },
+                );
                 models.push(model);
             },
         );
@@ -1233,6 +1263,7 @@ impl Scene {
             depth_map.as_ref(),
         );
         let mut models = Vec::new();
+        let mut wipeout_sources = rustc_hash::FxHashMap::default();
         graph.walk_root(
             self.render_scene_root(target_block),
             |entity, context| {
@@ -1279,7 +1310,34 @@ impl Scene {
                 } else {
                     bg_color
                 };
+                let render_instance = if context.is_instanced() {
+                    let matrix = &context.transform.matrix.m;
+                    let linear = [
+                        matrix[0][0].to_bits(), matrix[0][1].to_bits(), matrix[0][2].to_bits(),
+                        matrix[1][0].to_bits(), matrix[1][1].to_bits(), matrix[1][2].to_bits(),
+                        matrix[2][0].to_bits(), matrix[2][1].to_bits(), matrix[2][2].to_bits(),
+                    ];
+                    let key = (
+                        source.common.handle.value(),
+                        linear,
+                        boundary
+                            .iter()
+                            .flat_map(|point| point.map(f32::to_bits))
+                            .collect::<Vec<_>>(),
+                        color.map(f32::to_bits),
+                    );
+                    let source_id = *wipeout_sources.entry(key).or_insert_with(
+                        crate::scene::model::instance_model::next_source_id,
+                    );
+                    Some(crate::scene::model::instance_model::RenderInstance {
+                        source_id,
+                        translation: [matrix[0][3], matrix[1][3], matrix[2][3]],
+                    })
+                } else {
+                    None
+                };
                 models.push(HatchModel {
+                    render_instance,
                     boundary: Arc::new(boundary),
                     boundary_wcs: None,
                     pattern: model::hatch_model::HatchPattern::Solid,
@@ -1622,6 +1680,7 @@ impl Scene {
             .collect();
 
         Some(HatchModel {
+            render_instance: None,
             boundary: std::sync::Arc::new(boundary_f32),
             boundary_wcs: None,
             pattern,
@@ -1926,6 +1985,7 @@ impl Scene {
             })
             .collect();
         HatchModel {
+            render_instance: None,
             boundary: std::sync::Arc::new(boundary),
             boundary_wcs: None,
             pattern: model::hatch_model::HatchPattern::Solid,