1 files changed, 97 insertions, 0 deletions
diff --git a/source/blender/blenkernel/BKE_surface_hook.h b/source/blender/blenkernel/BKE_surface_hook.h
new file mode 100644
index 00000000000..d1f7e19c674
--- /dev/null
+++ b/source/blender/blenkernel/BKE_surface_hook.h
@@ -0,0 +1,97 @@
+#ifndef __BKE_SURFACE_HOOK_H__
+#define __BKE_SURFACE_HOOK_H__
+
+#include "BLI_float3.h"
+#include "BLI_utildefines.h"
+
+#include "BKE_id_handle.h"
+
+namespace BKE {
+
+using BLI::float3;
+
+namespace SurfaceHookType {
+enum Enum {
+  None,
+  MeshObject,
+};
+}
+
+/**
+ * References a point on a surface. If the surface moves, the point moves with it.
+ */
+class SurfaceHook {
+ private:
+  SurfaceHookType::Enum m_type;
+
+  /**
+   * Used to identify the object if m_type is MeshObject.
+   */
+  ObjectIDHandle m_object_handle;
+
+  /* Index of the triangle that contains the referenced location. */
+  uint32_t m_triangle_index;
+
+  /* Barycentric coordinates of the referenced location inside the triangle. */
+  float3 m_bary_coords;
+
+ public:
+  SurfaceHook() : m_type(SurfaceHookType::None)
+  {
+  }
+
+  SurfaceHook(ObjectIDHandle object_handle, uint32_t triangle_index, float3 bary_coords)
+      : m_type(SurfaceHookType::MeshObject),
+        m_object_handle(object_handle),
+        m_triangle_index(triangle_index),
+        m_bary_coords(bary_coords)
+  {
+  }
+
+  SurfaceHookType::Enum type() const
+  {
+    return m_type;
+  }
+
+  bool is_valid() const
+  {
+    return m_type != SurfaceHookType::None;
+  }
+
+  ObjectIDHandle object_handle() const
+  {
+    BLI_assert(m_type == SurfaceHookType::MeshObject);
+    return m_object_handle;
+  }
+
+  uint32_t triangle_index() const
+  {
+    BLI_assert(m_type == SurfaceHookType::MeshObject);
+    return m_triangle_index;
+  }
+
+  float3 bary_coords() const
+  {
+    BLI_assert(m_type == SurfaceHookType::MeshObject);
+    return m_bary_coords;
+  }
+
+  static bool on_same_surface(const SurfaceHook &a, const SurfaceHook &b)
+  {
+    if (a.type() != b.type()) {
+      return false;
+    }
+    switch (a.type()) {
+      case BKE::SurfaceHookType::None:
+        return true;
+      case BKE::SurfaceHookType::MeshObject:
+        return a.object_handle() == b.object_handle();
+    }
+    BLI_assert(false);
+    return false;
+  }
+};
+
+}  // namespace BKE
+
+#endif /* __BKE_SURFACE_HOOK_H__ */