diff --git a/libs/yocto/yocto_scene.cpp b/libs/yocto/yocto_scene.cpp
index 06e720037..385e72807 100644
--- a/libs/yocto/yocto_scene.cpp
+++ b/libs/yocto/yocto_scene.cpp
@@ -106,56 +106,6 @@ ray3f eval_camera(const camera_data& camera, vec2f image_uv, vec2f lens_uv) {
 
 }  // namespace yocto
 
-// -----------------------------------------------------------------------------
-// SHAPE FUNCTIONS
-// -----------------------------------------------------------------------------
-namespace yocto {
-
-// Shape creation
-template <typename PFunc, typename TFunc>
-inline shape_data make_lines(int steps, PFunc&& position, TFunc&& tangent) {
-  auto shape      = shape_data{};
-  shape.positions = vector<vec3f>(steps + 1);
-  shape.normals   = vector<vec3f>(steps + 1);
-  shape.texcoords = vector<vec2f>(steps + 1);
-  for (auto idx : range(steps + 1)) {
-    auto u               = (float)idx / (float)steps;
-    shape.positions[idx] = position(u);
-    shape.normals[idx]   = tangent(u);
-    shape.texcoords[idx] = {u, 0};
-  }
-  shape.lines = vector<vec2i>(steps);
-  for (auto idx : range(steps)) shape.lines[idx] = {idx, idx + 1};
-  return shape;
-}
-template <typename PFunc, typename NFunc>
-inline shape_data make_quads(vec2i steps, PFunc&& position, NFunc&& normal) {
-  auto shape      = shape_data{};
-  shape.positions = vector<vec3f>((steps.x + 1) * (steps.y + 1));
-  shape.normals   = vector<vec3f>((steps.x + 1) * (steps.y + 1));
-  shape.texcoords = vector<vec2f>((steps.x + 1) * (steps.y + 1));
-  for (auto j : range(steps.y + 1)) {
-    for (auto i : range(steps.x + 1)) {
-      auto uv              = vec2f{i / (float)steps.x, j / (float)steps.y};
-      auto idx             = j * (steps.x + 1) + i;
-      shape.positions[idx] = position(uv);
-      shape.normals[idx]   = normal(uv);
-      shape.texcoords[idx] = uv;
-    }
-  }
-  shape.quads = vector<vec4i>(steps.x * steps.y);
-  for (auto j : range(steps.y)) {
-    for (auto i : range(steps.x)) {
-      auto idx         = j * steps.x + i;
-      shape.quads[idx] = {j * (steps.x + 1) + i, j * (steps.x + 1) + i + 1,
-          (j + 1) * (steps.x + 1) + i + 1, (j + 1) * (steps.x + 1) + i};
-    }
-  }
-  return shape;
-}
-
-}  // namespace yocto
-
 // -----------------------------------------------------------------------------
 // IMPLEMENTATION FO SHAPE PROPERTIES
 // -----------------------------------------------------------------------------
diff --git a/libs/yocto/yocto_scene.h b/libs/yocto/yocto_scene.h
index 63b2ccc55..96994d35f 100644
--- a/libs/yocto/yocto_scene.h
+++ b/libs/yocto/yocto_scene.h
@@ -323,9 +323,9 @@ shape_data subdivide_shape(
 
 // Shape displacement
 shape_data displace_shape(const shape_data& shape,
-    const image_t<float>& displacement, float height, float offset);
+    const image_t<float>& displacement, float height = 1, float offset = 0.5f);
 shape_data displace_shape(const shape_data& shape,
-    const image_t<vec4f>& displacement, float height, float offset);
+    const image_t<vec4f>& displacement, float height = 1, float offset = 0.5f);
 
 // Shape sampling
 vector<float>    sample_shape_cdf(const shape_data& shape);
@@ -748,4 +748,62 @@ scene_data make_cornellbox();
 
 }  // namespace yocto
 
+// -----------------------------------------------------------------------------
+//
+//
+// IMPLEMENTATION
+//
+//
+// -----------------------------------------------------------------------------
+
+// -----------------------------------------------------------------------------
+// SHAPE FUNCTIONS
+// -----------------------------------------------------------------------------
+namespace yocto {
+
+// Shape creation
+template <typename PFunc, typename TFunc>
+inline shape_data make_lines(int steps, PFunc&& position, TFunc&& tangent) {
+  auto shape      = shape_data{};
+  shape.positions = vector<vec3f>(steps + 1);
+  shape.normals   = vector<vec3f>(steps + 1);
+  shape.texcoords = vector<vec2f>(steps + 1);
+  for (auto idx : range(steps + 1)) {
+    auto u               = (float)idx / (float)steps;
+    shape.positions[idx] = position(u);
+    shape.normals[idx]   = tangent(u);
+    shape.texcoords[idx] = {u, 0};
+  }
+  shape.lines = vector<vec2i>(steps);
+  for (auto idx : range(steps)) shape.lines[idx] = {idx, idx + 1};
+  return shape;
+}
+template <typename PFunc, typename NFunc>
+inline shape_data make_quads(vec2i steps, PFunc&& position, NFunc&& normal) {
+  auto shape      = shape_data{};
+  shape.positions = vector<vec3f>((steps.x + 1) * (steps.y + 1));
+  shape.normals   = vector<vec3f>((steps.x + 1) * (steps.y + 1));
+  shape.texcoords = vector<vec2f>((steps.x + 1) * (steps.y + 1));
+  for (auto j : range(steps.y + 1)) {
+    for (auto i : range(steps.x + 1)) {
+      auto uv              = vec2f{i / (float)steps.x, j / (float)steps.y};
+      auto idx             = j * (steps.x + 1) + i;
+      shape.positions[idx] = position(uv);
+      shape.normals[idx]   = normal(uv);
+      shape.texcoords[idx] = uv;
+    }
+  }
+  shape.quads = vector<vec4i>(steps.x * steps.y);
+  for (auto j : range(steps.y)) {
+    for (auto i : range(steps.x)) {
+      auto idx         = j * steps.x + i;
+      shape.quads[idx] = {j * (steps.x + 1) + i, j * (steps.x + 1) + i + 1,
+          (j + 1) * (steps.x + 1) + i + 1, (j + 1) * (steps.x + 1) + i};
+    }
+  }
+  return shape;
+}
+
+}  // namespace yocto
+
 #endif