diff --git a/src/viewport-three/viewport-view-modes.ts b/src/viewport-three/viewport-view-modes.ts
new file mode 100644
index 00000000..9cbc7a3a
--- /dev/null
+++ b/src/viewport-three/viewport-view-modes.ts
@@ -0,0 +1,114 @@
+import type { Vec3 } from "../core/vector";
+
+export type ViewportViewMode = "perspective" | "top" | "front" | "side";
+
+export const VIEWPORT_VIEW_MODES = ["perspective", "top", "front", "side"] as const;
+
+export type ViewportGridPlane = "xz" | "xy" | "yz";
+export type ViewportAxis = "x" | "y" | "z";
+
+export interface ViewportViewModeDefinition {
+  id: ViewportViewMode;
+  label: string;
+  cameraType: "perspective" | "orthographic";
+  cameraDirection: Vec3 | null;
+  cameraUp: Vec3;
+  gridPlane: ViewportGridPlane;
+  snapAxis: ViewportAxis;
+  controlHint: string;
+}
+
+const VIEWPORT_VIEW_MODE_DEFINITIONS: Record<ViewportViewMode, ViewportViewModeDefinition> = {
+  perspective: {
+    id: "perspective",
+    label: "Perspective",
+    cameraType: "perspective",
+    cameraDirection: null,
+    cameraUp: {
+      x: 0,
+      y: 1,
+      z: 0
+    },
+    gridPlane: "xz",
+    snapAxis: "y",
+    controlHint: "Middle-drag orbits, Shift + middle-drag pans, wheel zooms, and Numpad Comma frames the selection."
+  },
+  top: {
+    id: "top",
+    label: "Top",
+    cameraType: "orthographic",
+    cameraDirection: {
+      x: 0,
+      y: 1,
+      z: 0
+    },
+    cameraUp: {
+      x: 0,
+      y: 0,
+      z: -1
+    },
+    gridPlane: "xz",
+    snapAxis: "y",
+    controlHint: "Middle-drag pans, wheel zooms, and Numpad Comma frames the selection."
+  },
+  front: {
+    id: "front",
+    label: "Front",
+    cameraType: "orthographic",
+    cameraDirection: {
+      x: 0,
+      y: 0,
+      z: 1
+    },
+    cameraUp: {
+      x: 0,
+      y: 1,
+      z: 0
+    },
+    gridPlane: "xy",
+    snapAxis: "z",
+    controlHint: "Middle-drag pans, wheel zooms, and Numpad Comma frames the selection."
+  },
+  side: {
+    id: "side",
+    label: "Side",
+    cameraType: "orthographic",
+    cameraDirection: {
+      x: -1,
+      y: 0,
+      z: 0
+    },
+    cameraUp: {
+      x: 0,
+      y: 1,
+      z: 0
+    },
+    gridPlane: "yz",
+    snapAxis: "x",
+    controlHint: "Middle-drag pans, wheel zooms, and Numpad Comma frames the selection."
+  }
+};
+
+export function getViewportViewModeDefinition(viewMode: ViewportViewMode): ViewportViewModeDefinition {
+  return VIEWPORT_VIEW_MODE_DEFINITIONS[viewMode];
+}
+
+export function getViewportViewModeLabel(viewMode: ViewportViewMode): string {
+  return VIEWPORT_VIEW_MODE_DEFINITIONS[viewMode].label;
+}
+
+export function getViewportViewModeGridPlaneLabel(viewMode: ViewportViewMode): string {
+  return VIEWPORT_VIEW_MODE_DEFINITIONS[viewMode].gridPlane.toUpperCase();
+}
+
+export function getViewportViewModeControlHint(viewMode: ViewportViewMode): string {
+  return VIEWPORT_VIEW_MODE_DEFINITIONS[viewMode].controlHint;
+}
+
+export function getViewportViewModeSnapAxis(viewMode: ViewportViewMode): ViewportAxis {
+  return VIEWPORT_VIEW_MODE_DEFINITIONS[viewMode].snapAxis;
+}
+
+export function isOrthographicViewportViewMode(viewMode: ViewportViewMode): boolean {
+  return viewMode !== "perspective";
+}