From ea2927fb8c52751d23b6dc540a65ba1de42cb8e2 Mon Sep 17 00:00:00 2001
From: Victor Giers <mail@victorgiers.com>
Date: Tue, 31 Mar 2026 04:23:06 +0200
Subject: [PATCH] Add viewport focus logic

---
 src/viewport-three/viewport-focus.ts | 170 +++++++++++++++++++++++++++
 1 file changed, 170 insertions(+)
 create mode 100644 src/viewport-three/viewport-focus.ts

diff --git a/src/viewport-three/viewport-focus.ts b/src/viewport-three/viewport-focus.ts
new file mode 100644
index 00000000..9167883e
--- /dev/null
+++ b/src/viewport-three/viewport-focus.ts
@@ -0,0 +1,170 @@
+import { getSingleSelectedBrushId, getSingleSelectedEntityId, type EditorSelection } from "../core/selection";
+import type { Vec3 } from "../core/vector";
+import type { BoxBrush } from "../document/brushes";
+import type { SceneDocument } from "../document/scene-document";
+
+const PLAYER_START_FOCUS_HALF_EXTENTS: Vec3 = {
+  x: 0.35,
+  y: 0.3,
+  z: 0.55
+};
+
+interface FocusBoundsAccumulator {
+  min: Vec3;
+  max: Vec3;
+}
+
+export interface ViewportFocusTarget {
+  center: Vec3;
+  radius: number;
+}
+
+function createEmptyBoundsAccumulator(): FocusBoundsAccumulator {
+  return {
+    min: {
+      x: Number.POSITIVE_INFINITY,
+      y: Number.POSITIVE_INFINITY,
+      z: Number.POSITIVE_INFINITY
+    },
+    max: {
+      x: Number.NEGATIVE_INFINITY,
+      y: Number.NEGATIVE_INFINITY,
+      z: Number.NEGATIVE_INFINITY
+    }
+  };
+}
+
+function includeBounds(bounds: FocusBoundsAccumulator, min: Vec3, max: Vec3) {
+  bounds.min.x = Math.min(bounds.min.x, min.x);
+  bounds.min.y = Math.min(bounds.min.y, min.y);
+  bounds.min.z = Math.min(bounds.min.z, min.z);
+  bounds.max.x = Math.max(bounds.max.x, max.x);
+  bounds.max.y = Math.max(bounds.max.y, max.y);
+  bounds.max.z = Math.max(bounds.max.z, max.z);
+}
+
+function finishBounds(bounds: FocusBoundsAccumulator): ViewportFocusTarget | null {
+  if (!Number.isFinite(bounds.min.x) || !Number.isFinite(bounds.max.x)) {
+    return null;
+  }
+
+  const center = {
+    x: (bounds.min.x + bounds.max.x) * 0.5,
+    y: (bounds.min.y + bounds.max.y) * 0.5,
+    z: (bounds.min.z + bounds.max.z) * 0.5
+  };
+  const radius = Math.max(
+    0.5,
+    Math.hypot(bounds.max.x - bounds.min.x, bounds.max.y - bounds.min.y, bounds.max.z - bounds.min.z) * 0.5
+  );
+
+  return {
+    center,
+    radius
+  };
+}
+
+function createBrushFocusTarget(brush: BoxBrush): ViewportFocusTarget {
+  return {
+    center: {
+      ...brush.center
+    },
+    radius: Math.max(0.5, Math.hypot(brush.size.x, brush.size.y, brush.size.z) * 0.5)
+  };
+}
+
+function createPlayerStartFocusTarget(position: Vec3): ViewportFocusTarget {
+  return {
+    center: {
+      x: position.x,
+      y: position.y + PLAYER_START_FOCUS_HALF_EXTENTS.y,
+      z: position.z
+    },
+    radius: Math.max(
+      0.45,
+      Math.hypot(
+        PLAYER_START_FOCUS_HALF_EXTENTS.x,
+        PLAYER_START_FOCUS_HALF_EXTENTS.y,
+        PLAYER_START_FOCUS_HALF_EXTENTS.z
+      )
+    )
+  };
+}
+
+function includeBrush(bounds: FocusBoundsAccumulator, brush: BoxBrush) {
+  const halfSize = {
+    x: brush.size.x * 0.5,
+    y: brush.size.y * 0.5,
+    z: brush.size.z * 0.5
+  };
+
+  includeBounds(
+    bounds,
+    {
+      x: brush.center.x - halfSize.x,
+      y: brush.center.y - halfSize.y,
+      z: brush.center.z - halfSize.z
+    },
+    {
+      x: brush.center.x + halfSize.x,
+      y: brush.center.y + halfSize.y,
+      z: brush.center.z + halfSize.z
+    }
+  );
+}
+
+function includePlayerStart(bounds: FocusBoundsAccumulator, position: Vec3) {
+  includeBounds(
+    bounds,
+    {
+      x: position.x - PLAYER_START_FOCUS_HALF_EXTENTS.x,
+      y: position.y,
+      z: position.z - PLAYER_START_FOCUS_HALF_EXTENTS.z
+    },
+    {
+      x: position.x + PLAYER_START_FOCUS_HALF_EXTENTS.x,
+      y: position.y + PLAYER_START_FOCUS_HALF_EXTENTS.y * 2,
+      z: position.z + PLAYER_START_FOCUS_HALF_EXTENTS.z
+    }
+  );
+}
+
+function getSceneFocusTarget(document: SceneDocument): ViewportFocusTarget | null {
+  const bounds = createEmptyBoundsAccumulator();
+
+  for (const brush of Object.values(document.brushes)) {
+    includeBrush(bounds, brush);
+  }
+
+  for (const entity of Object.values(document.entities)) {
+    if (entity.kind === "playerStart") {
+      includePlayerStart(bounds, entity.position);
+    }
+  }
+
+  return finishBounds(bounds);
+}
+
+export function resolveViewportFocusTarget(document: SceneDocument, selection: EditorSelection): ViewportFocusTarget | null {
+  const selectedBrushId = getSingleSelectedBrushId(selection);
+
+  if (selectedBrushId !== null) {
+    const brush = document.brushes[selectedBrushId];
+
+    if (brush !== undefined && brush.kind === "box") {
+      return createBrushFocusTarget(brush);
+    }
+  }
+
+  const selectedEntityId = getSingleSelectedEntityId(selection);
+
+  if (selectedEntityId !== null) {
+    const entity = document.entities[selectedEntityId];
+
+    if (entity?.kind === "playerStart") {
+      return createPlayerStartFocusTarget(entity.position);
+    }
+  }
+
+  return getSceneFocusTarget(document);
+}