Reduce default heightmap sampling from 2 to 1 (#459)

Signed-off-by: Louise Poubel <louise@openrobotics.org>

Migration.md

@@ -43,6 +43,8 @@ but with improved human-readability..
     + bool JointNameExists(const std::string &) const
     + bool LinkNameExists(const std::string &) const
 
+1. **sdf/Heightmap.hh**: sampling now defaults to 1 instead of 2.
+
 ### Deprecations
 
 1. **src/Root.hh**: The following methods have been deprecated in favor of the
@@ -308,6 +310,8 @@ but with improved human-readability..
 1. **joint.sdf** `child` and `parent` elements accept frame names instead of only link names
     * [Issue 204](https://github.com/osrf/sdformat/issues/204)
 
+1. **heightmap.sdf**: sampling now defaults to 1 instead of 2.
+
 ### Deprecations
 
 1. **joint.sdf** `initial_position` element in `<joint><axis>` and `<joint><axis2>` is deprecated

include/sdf/Heightmap.hh

@@ -242,7 +242,7 @@ namespace sdf
     /// \return The heightmap's sampling.
     public: unsigned int Sampling() const;
 
-    /// \brief Set the heightmap's sampling. Defaults to 2.
+    /// \brief Set the heightmap's sampling. Defaults to 1.
     /// \param[in] _sampling The heightmap's sampling per datum.
     public: void SetSampling(unsigned int _sampling);
 

sdf/1.8/heightmap_shape.sdf

@@ -37,8 +37,8 @@
   <element name="use_terrain_paging" type="bool" default="false" required="0">
     <description>Set if the rendering engine will use terrain paging</description>
   </element>
-  <element name="sampling" type="unsigned int" default="2" required="0">
-    <description>Samples per heightmap datum. For rasterized heightmaps, this indicates the number of samples to take per pixel. Using a lower value, e.g. 1, will generally improve the performance of the heightmap but lower the heightmap quality.
+  <element name="sampling" type="unsigned int" default="1" required="0">
+    <description>Samples per heightmap datum. For rasterized heightmaps, this indicates the number of samples to take per pixel. Using a higher value, e.g. 2, will generally improve the quality of the heightmap but lower performance.
     </description>
   </element>
 </element>

src/Heightmap.cc

@@ -70,7 +70,7 @@ class sdf::HeightmapPrivate
   public: bool useTerrainPaging{false};
 
   /// \brief Sampling per datum.
-  public: unsigned int sampling{2u};
+  public: unsigned int sampling{1u};
 
   /// \brief Textures in order
   public: std::vector<HeightmapTexture> textures;

src/Heightmap_TEST.cc

@@ -29,7 +29,7 @@ TEST(DOMHeightmap, Construction)
   EXPECT_EQ(ignition::math::Vector3d(1, 1, 1), heightmap.Size());
   EXPECT_EQ(ignition::math::Vector3d::Zero, heightmap.Position());
   EXPECT_FALSE(heightmap.UseTerrainPaging());
-  EXPECT_EQ(2u, heightmap.Sampling());
+  EXPECT_EQ(1u, heightmap.Sampling());
   EXPECT_EQ(0u, heightmap.TextureCount());
   EXPECT_EQ(0u, heightmap.BlendCount());
   EXPECT_EQ(nullptr, heightmap.TextureByIndex(0u));
@@ -304,7 +304,7 @@ TEST(DOMHeightmap, Set)
   heightmap.SetUseTerrainPaging(true);
   EXPECT_TRUE(heightmap.UseTerrainPaging());
 
-  EXPECT_EQ(2u, heightmap.Sampling());
+  EXPECT_EQ(1u, heightmap.Sampling());
   heightmap.SetSampling(12u);
   EXPECT_EQ(12u, heightmap.Sampling());