From b8ce7b7639a019dc2b48795f4791224782eb343a Mon Sep 17 00:00:00 2001
From: Jeongseok Lee <jslee02@gmail.com>
Date: Mon, 25 Mar 2024 18:22:37 -0700
Subject: [PATCH] [example] Update hello world

---
 examples/hello_world/main.cpp | 42 +++++++++++++++++++++++++++++------
 pixi.toml                     |  3 +++
 2 files changed, 38 insertions(+), 7 deletions(-)

diff --git a/examples/hello_world/main.cpp b/examples/hello_world/main.cpp
index b58b25a948dbf..20a64bb0aabac 100644
--- a/examples/hello_world/main.cpp
+++ b/examples/hello_world/main.cpp
@@ -34,26 +34,45 @@
 
 #include <dart/dart.hpp>
 
+#include <osgShadow/ShadowMap>
+
 using namespace dart;
 
 int main()
 {
-  auto shape
-      = std::make_shared<dynamics::BoxShape>(Eigen::Vector3d(0.3, 0.3, 0.3));
-
   // Create a box-shaped rigid body
   auto skeleton = dynamics::Skeleton::create();
   auto jointAndBody
       = skeleton->createJointAndBodyNodePair<dynamics::FreeJoint>();
   auto body = jointAndBody.second;
-  body->createShapeNodeWith<
+  Eigen::Isometry3d tf = Eigen::Isometry3d::Identity();
+  tf.translation() << 0, 0, 1;
+  tf.linear() = math::expMapRot(Eigen::Vector3d::Random());
+  body->getParentJoint()->setTransformFromParentBodyNode(tf);
+  auto shapeNode = body->createShapeNodeWith<
+      dynamics::VisualAspect,
+      dynamics::CollisionAspect,
+      dynamics::DynamicsAspect>(
+      std::make_shared<dynamics::BoxShape>(Eigen::Vector3d(0.3, 0.3, 0.3)));
+  body->setInertia(dynamics::Inertia(
+      1, Eigen::Vector3d::Zero(), shapeNode->getShape()->computeInertia(1.0)));
+  shapeNode->getVisualAspect()->setColor(dart::Color::Blue());
+
+  // Create ground
+  auto ground = dynamics::Skeleton::create("ground");
+  auto groundBody
+      = ground->createJointAndBodyNodePair<dynamics::WeldJoint>().second;
+  auto groundShapeNode = groundBody->createShapeNodeWith<
       dynamics::VisualAspect,
       dynamics::CollisionAspect,
-      dynamics::DynamicsAspect>(shape);
+      dynamics::DynamicsAspect>(
+      std::make_shared<dynamics::BoxShape>(Eigen::Vector3d(10.0, 10.0, 0.1)));
+  groundShapeNode->getVisualAspect()->setColor(dart::Color::LightGray());
 
-  // Create a world and add the rigid body
+  // Create a world and add the rigid body and ground to the world
   auto world = simulation::World::create();
   world->addSkeleton(skeleton);
+  world->addSkeleton(ground);
 
   // Wrap a WorldNode around it
   ::osg::ref_ptr<gui::osg::RealTimeWorldNode> node
@@ -63,6 +82,15 @@ int main()
   auto viewer = gui::osg::Viewer();
   viewer.addWorldNode(node);
 
+  // Enable shadow
+  auto shadow
+      = dart::gui::osg::WorldNode::createDefaultShadowTechnique(&viewer);
+  if (auto sm = dynamic_cast<::osgShadow::ShadowMap*>(shadow.get())) {
+    auto mapResolution = static_cast<short>(std::pow(2, 12));
+    sm->setTextureSize(::osg::Vec2s(mapResolution, mapResolution));
+  }
+  node->setShadowTechnique(shadow);
+
   viewer.addInstructionText("Press space to start free falling the box.\n");
   std::cout << viewer.getInstructions() << std::endl;
 
@@ -72,7 +100,7 @@ int main()
   // Adjust the viewpoint of the Viewer
   viewer.getCameraManipulator()->setHomePosition(
       ::osg::Vec3(2.57f, 3.14f, 1.64f),
-      ::osg::Vec3(0.00f, 0.00f, 0.00f),
+      ::osg::Vec3(0.00f, 0.00f, 0.50f),
       ::osg::Vec3(-0.24f, -0.25f, 0.94f));
 
   // We need to re-dirty the CameraManipulator by passing it into the viewer
diff --git a/pixi.toml b/pixi.toml
index 07c625269c2cf..68663b9ae38cd 100644
--- a/pixi.toml
+++ b/pixi.toml
@@ -13,6 +13,9 @@ install-local = { cmd = "cmake --install build --prefix $CONDA_PREFIX", depends_
     "configure_local",
     "build",
 ] }
+example-hello-world = { cmd = "cmake --build build --target hello_world --parallel && ./build/bin/hello_world", depends_on = [
+    "configure",
+] }
 example-atlas-puppet = { cmd = "cmake --build build --target atlas_puppet --parallel && ./build/bin/atlas_puppet", depends_on = [
     "configure",
 ] }