Render heightmap to layer

src/shape.h

@@ -125,7 +125,7 @@ public:
 class HeightmapPlane : public Shape
 {
 public:
-    bool create(float w, float h, const Image& img, float scale);
+    bool create(float w, float h, const Image& img, float scale, float height);
     bool create(float w, float h, int div);
 };