From cf071f8b32bc0ff39190d4ef48d021e96e890062 Mon Sep 17 00:00:00 2001
From: Yuwei Xiao <xyw1105@126.com>
Date: Wed, 11 Mar 2020 00:25:17 +0800
Subject: [PATCH] ex1 update
---
1-0_earth/CMakeLists.txt | 43 +++++++++
1-0_earth/EarthSim.h | 93 +++++++++++++++++++
1-0_earth/main.cpp | 41 ++++++++
1-1_cannonball/CMakeLists.txt | 43 +++++++++
1-1_cannonball/CannonBallSim.cpp | 45 +++++++++
1-1_cannonball/CannonBallSim.h | 151 ++++++++++++++++++++++++++++++
1-1_cannonball/main.cpp | 96 +++++++++++++++++++
1-2_spring/CMakeLists.txt | 43 +++++++++
1-2_spring/SpringSim.cpp | 50 ++++++++++
1-2_spring/SpringSim.h | 154 +++++++++++++++++++++++++++++++
1-2_spring/main.cpp | 123 ++++++++++++++++++++++++
CMakeLists.txt | 5 +-
include/Simulation.h | 1 +
13 files changed, 887 insertions(+), 1 deletion(-)
create mode 100644 1-0_earth/CMakeLists.txt
create mode 100644 1-0_earth/EarthSim.h
create mode 100644 1-0_earth/main.cpp
create mode 100644 1-1_cannonball/CMakeLists.txt
create mode 100644 1-1_cannonball/CannonBallSim.cpp
create mode 100644 1-1_cannonball/CannonBallSim.h
create mode 100644 1-1_cannonball/main.cpp
create mode 100644 1-2_spring/CMakeLists.txt
create mode 100644 1-2_spring/SpringSim.cpp
create mode 100644 1-2_spring/SpringSim.h
create mode 100644 1-2_spring/main.cpp
diff --git a/1-0_earth/CMakeLists.txt b/1-0_earth/CMakeLists.txt
new file mode 100644
index 0000000..da74f69
--- /dev/null
+++ b/1-0_earth/CMakeLists.txt
@@ -0,0 +1,43 @@
+
+cmake_minimum_required(VERSION 3.1)
+project(1_earth)
+
+set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CMAKE_CURRENT_SOURCE_DIR}/../cmake)
+set(CMAKE_CXX_FLAGS "-Wall")
+
+# libigl
+option(LIBIGL_USE_STATIC_LIBRARY "Use libigl as static library" OFF)
+option(LIBIGL_WITH_ANTTWEAKBAR "Use AntTweakBar" OFF)
+option(LIBIGL_WITH_CGAL "Use CGAL" OFF)
+option(LIBIGL_WITH_COMISO "Use CoMiso" OFF)
+option(LIBIGL_WITH_CORK "Use Cork" OFF)
+option(LIBIGL_WITH_EMBREE "Use Embree" OFF)
+option(LIBIGL_WITH_LIM "Use LIM" OFF)
+option(LIBIGL_WITH_MATLAB "Use Matlab" OFF)
+option(LIBIGL_WITH_MOSEK "Use MOSEK" OFF)
+option(LIBIGL_WITH_OPENGL "Use OpenGL" ON)
+option(LIBIGL_WITH_OPENGL_GLFW "Use GLFW" ON)
+option(LIBIGL_WITH_OPENGL_GLFW_IMGUI "Use ImGui" ON)
+option(LIBIGL_WITH_PNG "Use PNG" OFF)
+option(LIBIGL_WITH_PYTHON "Use Python" OFF)
+option(LIBIGL_WITH_TETGEN "Use Tetgen" OFF)
+option(LIBIGL_WITH_TRIANGLE "Use Triangle" OFF)
+option(LIBIGL_WITH_VIEWER "Use OpenGL viewer" ON)
+option(LIBIGL_WITH_XML "Use XML" OFF)
+
+if (NOT LIBIGL_FOUND)
+ find_package(LIBIGL REQUIRED QUIET)
+endif()
+
+# Add default project files
+file(GLOB LIBFILES ${PROJECT_SOURCE_DIR}/../include/*.*)
+source_group("Library Files" FILES ${LIBFILES})
+include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../include)
+
+# Add your project files
+file(GLOB SRCFILES *.cpp)
+file(GLOB HFILES *.h)
+
+add_definitions(-DIGL_VIEWER_VIEWER_QUIET)
+add_executable(${PROJECT_NAME} ${SRCFILES} ${HFILES} ${LIBFILES} )
+target_link_libraries(${PROJECT_NAME} igl::core igl::opengl_glfw igl::opengl_glfw_imgui)
\ No newline at end of file
diff --git a/1-0_earth/EarthSim.h b/1-0_earth/EarthSim.h
new file mode 100644
index 0000000..f02088e
--- /dev/null
+++ b/1-0_earth/EarthSim.h
@@ -0,0 +1,93 @@
+#include "Simulation.h"
+
+using namespace std;
+
+
+class EarthSim : public Simulation {
+public:
+ EarthSim() : Simulation() {
+ init();
+ }
+
+ virtual void init() override {
+ std::string path = "sphere.off";
+ m_objects.clear();
+ m_objects.push_back(RigidObject(path));
+ m_objects.push_back(RigidObject(path));
+ p_earth = &m_objects[0];
+ p_moon = &m_objects[1];
+
+ m_dt = 5e-2;
+ m_radius = 10;
+
+ reset();
+ }
+
+ virtual void resetMembers() override {
+ p_earth->reset();
+ p_earth->setScale(0.3);
+ p_earth->setPosition(Eigen::Vector3d(0, 0, 0));
+
+ p_moon->reset();
+ p_moon->setScale(0.1);
+ p_moon->setPosition(Eigen::Vector3d(cos(getTime()), 0, sin(getTime())) * m_radius);
+ }
+
+ virtual void updateRenderGeometry() override {
+ for (size_t i = 0; i < m_objects.size(); i++) {
+ RigidObject &o = m_objects[i];
+ if (o.getID() < 0) { // negative id means newly created object, reverse memory for it
+ m_renderVs.emplace_back();
+ m_renderFs.emplace_back();
+ }
+
+ m_objects[i].getMesh(m_renderVs[i], m_renderFs[i]);
+ }
+ }
+
+ virtual bool advance() override {
+ // TODO update p_moon
+
+ // update m_time
+ // update m_step
+
+ return false;
+ }
+
+ virtual void renderRenderGeometry(igl::opengl::glfw::Viewer &viewer) override {
+ for (size_t i = 0; i < m_objects.size(); i++) {
+ RigidObject &o = m_objects[i];
+ if (o.getID() < 0) {
+ int new_id = 0;
+ if (i > 0) {
+ new_id = viewer.append_mesh();
+ o.setID(new_id);
+ } else {
+ o.setID(new_id);
+ }
+
+ size_t meshIndex = viewer.mesh_index(o.getID());
+ viewer.data_list[meshIndex].set_face_based(true);
+ viewer.data_list[meshIndex].point_size = 2.0f;
+ viewer.data_list[meshIndex].clear();
+ }
+ size_t meshIndex = viewer.mesh_index(o.getID());
+
+ viewer.data_list[meshIndex].set_mesh(m_renderVs[i], m_renderFs[i]);
+ viewer.data_list[meshIndex].compute_normals();
+
+ Eigen::MatrixXd color;
+ o.getColors(color);
+ viewer.data_list[meshIndex].set_colors(color);
+ }
+ }
+
+ void setRadius(float r) { m_radius = r; }
+
+private:
+ RigidObject *p_earth, *p_moon;
+ float m_radius;
+
+ std::vector<Eigen::MatrixXd> m_renderVs; // vertex positions for rendering
+ std::vector<Eigen::MatrixXi> m_renderFs; // face indices for rendering
+};
\ No newline at end of file
diff --git a/1-0_earth/main.cpp b/1-0_earth/main.cpp
new file mode 100644
index 0000000..c6a1c1b
--- /dev/null
+++ b/1-0_earth/main.cpp
@@ -0,0 +1,41 @@
+#include "EarthSim.h"
+#include "Gui.h"
+
+/*
+ * GUI for the earth simulation.
+ */
+class EarthGui : public Gui {
+ public:
+ // simulation parameters
+ float m_dt = 1e-2;
+ float m_radius = 10.0;
+
+ EarthSim *p_EarthSim = NULL;
+
+ EarthGui() {
+ // create a new Earth simulation, set it in the GUI, and start the GUI
+ p_EarthSim = new EarthSim();
+ setSimulation(p_EarthSim);
+
+ start();
+ }
+
+ virtual void updateSimulationParameters() override {
+ // change all parameters of the simulation to the values that are set in the GUI
+ p_EarthSim->setTimestep(m_dt);
+ p_EarthSim->setRadius(m_radius);
+ }
+
+
+ virtual void drawSimulationParameterMenu() override {
+ ImGui::InputFloat("Radius", &m_radius, 0, 0);
+ ImGui::InputFloat("dt", &m_dt, 0, 0);
+ }
+};
+
+int main(int argc, char *argv[]) {
+ // create a new instance of the GUI for the Earth simulation
+ new EarthGui();
+
+ return 0;
+}
\ No newline at end of file
diff --git a/1-1_cannonball/CMakeLists.txt b/1-1_cannonball/CMakeLists.txt
new file mode 100644
index 0000000..d91cc47
--- /dev/null
+++ b/1-1_cannonball/CMakeLists.txt
@@ -0,0 +1,43 @@
+
+cmake_minimum_required(VERSION 3.1)
+project(1-1_cannonball)
+
+set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CMAKE_CURRENT_SOURCE_DIR}/../cmake)
+set(CMAKE_CXX_FLAGS "-Wall")
+
+# libigl
+option(LIBIGL_USE_STATIC_LIBRARY "Use libigl as static library" OFF)
+option(LIBIGL_WITH_ANTTWEAKBAR "Use AntTweakBar" OFF)
+option(LIBIGL_WITH_CGAL "Use CGAL" OFF)
+option(LIBIGL_WITH_COMISO "Use CoMiso" OFF)
+option(LIBIGL_WITH_CORK "Use Cork" OFF)
+option(LIBIGL_WITH_EMBREE "Use Embree" OFF)
+option(LIBIGL_WITH_LIM "Use LIM" OFF)
+option(LIBIGL_WITH_MATLAB "Use Matlab" OFF)
+option(LIBIGL_WITH_MOSEK "Use MOSEK" OFF)
+option(LIBIGL_WITH_OPENGL "Use OpenGL" ON)
+option(LIBIGL_WITH_OPENGL_GLFW "Use GLFW" ON)
+option(LIBIGL_WITH_OPENGL_GLFW_IMGUI "Use ImGui" ON)
+option(LIBIGL_WITH_PNG "Use PNG" OFF)
+option(LIBIGL_WITH_PYTHON "Use Python" OFF)
+option(LIBIGL_WITH_TETGEN "Use Tetgen" OFF)
+option(LIBIGL_WITH_TRIANGLE "Use Triangle" OFF)
+option(LIBIGL_WITH_VIEWER "Use OpenGL viewer" ON)
+option(LIBIGL_WITH_XML "Use XML" OFF)
+
+if (NOT LIBIGL_FOUND)
+ find_package(LIBIGL REQUIRED QUIET)
+endif()
+
+# Add default project files
+file(GLOB LIBFILES ${PROJECT_SOURCE_DIR}/../include/*.*)
+source_group("Library Files" FILES ${LIBFILES})
+include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../include)
+
+# Add your project files
+file(GLOB SRCFILES *.cpp)
+file(GLOB HFILES *.h)
+
+add_definitions(-DIGL_VIEWER_VIEWER_QUIET)
+add_executable(${PROJECT_NAME} ${SRCFILES} ${HFILES} ${LIBFILES} )
+target_link_libraries(${PROJECT_NAME} igl::core igl::opengl_glfw igl::opengl_glfw_imgui)
\ No newline at end of file
diff --git a/1-1_cannonball/CannonBallSim.cpp b/1-1_cannonball/CannonBallSim.cpp
new file mode 100644
index 0000000..0eafcfa
--- /dev/null
+++ b/1-1_cannonball/CannonBallSim.cpp
@@ -0,0 +1,45 @@
+#include "CannonBallSim.h"
+
+
+bool CannonBallSim::advance() {
+ // perform time integration with different integrators
+
+ // use p_ball, m_dt, m_gravity
+ Eigen::Vector3d v = p_ball->getLinearVelocity();
+ Eigen::Vector3d p = p_ball->getPosition();
+
+ // TODO
+ switch (m_method) {
+ case 0:
+ // analytical solution
+ // v(t) = v_0*t + 0.5*a*t^2
+ break;
+
+ case 1:
+ // explicit euler
+ // p' = p + dt*v
+ // v' = v + dt*a
+ break;
+
+ case 2:
+ // symplectic euler
+ // v' = v + dt*a
+ // p' = p + dt*v'
+ break;
+
+ default:
+ std::cerr << m_method << " is not a valid integrator method."
+ << std::endl;
+ }
+
+ // advance time
+ m_time += m_dt;
+ m_step++;
+
+ // log
+ if ((m_step % m_log_frequency) == 0) {
+ m_trajectories.back().push_back(p_ball->getPosition());
+ }
+
+ return false;
+}
\ No newline at end of file
diff --git a/1-1_cannonball/CannonBallSim.h b/1-1_cannonball/CannonBallSim.h
new file mode 100644
index 0000000..4584f97
--- /dev/null
+++ b/1-1_cannonball/CannonBallSim.h
@@ -0,0 +1,151 @@
+#include "Simulation.h"
+
+using namespace std;
+
+/*
+ * Simulation that shoots a sphere in a given direction with a given force using
+ * several kinds of integrators.
+ */
+class CannonBallSim : public Simulation {
+public:
+ CannonBallSim() : Simulation() {
+ init();
+ m_trajectories.clear();
+ m_trajectoryColors.clear();
+ }
+
+ virtual void init() override {
+ std::string path = "sphere.off";
+ m_objects.clear();
+ m_objects.push_back(RigidObject(path));
+ p_ball = &m_objects.back();
+
+ m_dt = 5e-2;
+ m_mass = 1.0;
+ m_log_frequency = 5;
+ m_method = 0;
+ m_gravity << 0, -9.81, 0;
+
+ reset();
+ }
+
+ virtual void resetMembers() override {
+ p_ball->reset();
+ p_ball->setScale(0.1);
+ p_ball->setPosition(Eigen::Vector3d(0, 0, 0));
+ p_ball->setMass(m_mass);
+ updateVars();
+
+ if (m_trajectories.size() == 0 || m_trajectories.back().size() > 1) {
+ m_trajectories.push_back(vector<Eigen::Vector3d>());
+ m_trajectoryColors.push_back(m_color);
+ } else {
+ m_trajectoryColors.back() = m_color;
+ }
+
+ setMethod(m_method);
+ }
+
+ virtual void updateRenderGeometry() override {
+ p_ball->getMesh(m_renderV, m_renderF);
+ }
+
+ virtual bool advance() override;
+
+ virtual void renderRenderGeometry(
+ igl::opengl::glfw::Viewer &viewer) override {
+ viewer.data().set_mesh(m_renderV, m_renderF);
+
+ for (size_t trajectory = 0; trajectory < m_trajectories.size();
+ trajectory++) {
+ for (size_t point = 0; point < m_trajectories[trajectory].size();
+ point++) {
+ viewer.data().add_points(
+ m_trajectories[trajectory][point].transpose(),
+ m_trajectoryColors[trajectory]);
+ }
+ }
+ }
+
+ void clearTrajectories() {
+ m_trajectories.clear();
+ m_trajectories.push_back(vector<Eigen::Vector3d>());
+ m_trajectoryColors.clear();
+ m_trajectoryColors.push_back(m_color);
+ }
+
+#pragma region SettersAndGetters
+ /*
+ * Compute magnitude and direction of momentum and apply it to ball
+ */
+ void updateVars() {
+ Eigen::Vector3d momentum;
+ momentum << std::cos(m_angle), std::sin(m_angle), 0;
+ momentum *= m_force;
+ p_ball->setLinearVelocity(momentum / p_ball->getMass());
+ }
+
+ void setAngle(double a) {
+ m_angle = a;
+ updateVars();
+ }
+
+ void setForce(double f) {
+ m_force = f;
+ updateVars();
+ }
+
+ void setMass(double m) { m_mass = m; }
+
+ void setMethod(int m) {
+ m_method = m;
+ switch (m_method) {
+ case 0:
+ m_color = Eigen::RowVector3d(1.0, 0.0, 0.0);
+ break;
+ case 1:
+ m_color = Eigen::RowVector3d(0.0, 1.0, 0.0);
+ break;
+ case 2:
+ m_color = Eigen::RowVector3d(0.0, 0.0, 1.0);
+ break;
+ default:
+ std::cerr << m_method << " is not a valid integrator method."
+ << std::endl;
+ }
+ if (m_step == 0) {
+ m_trajectoryColors.back() = m_color;
+ }
+ }
+
+ void setLogFrequency(int f) { m_log_frequency = f; }
+
+ void getTrajectories(int index, Eigen::MatrixX3d &mat) const {
+ int num_points = m_trajectories[index].size();
+ mat.resize(num_points, 3);
+ for (int i = 0; i < num_points; i++) {
+ mat.row(i) = m_trajectories[index][i];
+ }
+ }
+
+ int getNumTrajectories() const { return m_trajectories.size(); }
+#pragma endregion SettersAndGetters
+
+private:
+ int m_method; // id of integrator to be used (0: analytical, 1: explicit euler, 2: semi-implicit euler)
+ double m_angle;
+ double m_force;
+ double m_mass;
+
+ Eigen::Vector3d m_gravity;
+
+ RigidObject *p_ball;
+
+ Eigen::MatrixXd m_renderV; // vertex positions for rendering
+ Eigen::MatrixXi m_renderF; // face indices for rendering
+
+ int m_log_frequency; // how often should we log the COM in the GUI
+ vector<vector<Eigen::Vector3d> > m_trajectories;
+ Eigen::RowVector3d m_color;
+ vector<Eigen::RowVector3d> m_trajectoryColors;
+};
\ No newline at end of file
diff --git a/1-1_cannonball/main.cpp b/1-1_cannonball/main.cpp
new file mode 100644
index 0000000..eeba893
--- /dev/null
+++ b/1-1_cannonball/main.cpp
@@ -0,0 +1,96 @@
+#include <igl/writeOFF.h>
+#include "CannonBallSim.h"
+#include "Gui.h"
+
+/*
+ * GUI for the cannonball simulation. This time we need additional paramters,
+ * e.g. which integrator to use for the simulation and the force applied to the
+ * cannonball, and we also add some more visualizations (trajectories).
+ */
+class CannonBallGui : public Gui {
+ public:
+ // simulation parameters
+ float m_angle = 1.047f;
+ float m_force = 30.0f;
+ float m_dt = 1e-2;
+ float m_mass = 1.0;
+ int m_log_frequency = 30;
+
+ CannonBallSim *p_cannonBallSim = NULL;
+
+ const vector<char const *> m_integrators = {"Analytic", "Explicit Euler",
+ "Symplectic Euler"};
+ int m_selected_integrator = 0;
+
+ CannonBallGui() {
+ // create a new cannonball simulation, set it in the GUI,
+ // and start the GUI
+ p_cannonBallSim = new CannonBallSim();
+ setSimulation(p_cannonBallSim);
+
+ // show vertex velocity instead of normal
+ callback_clicked_vertex = [&](int clickedVertexIndex,
+ int clickedObjectIndex,
+ Eigen::Vector3d &pos,
+ Eigen::Vector3d &dir) {
+ RigidObject &o = p_cannonBallSim->getObjects()[clickedObjectIndex];
+ pos = o.getVertexPosition(clickedVertexIndex);
+ dir = o.getVelocity(pos);
+ };
+ start();
+ }
+
+ virtual void updateSimulationParameters() override {
+ // change all parameters of the simulation to the values that are set in
+ // the GUI
+ p_cannonBallSim->setForce(m_force);
+ p_cannonBallSim->setAngle(m_angle);
+ p_cannonBallSim->setTimestep(m_dt);
+ p_cannonBallSim->setMass(m_mass);
+ p_cannonBallSim->setMethod(m_selected_integrator);
+ p_cannonBallSim->setLogFrequency(m_log_frequency);
+ }
+
+ virtual void clearSimulation() override {
+ p_cannonBallSim->clearTrajectories();
+ }
+
+ /*
+ * Writes each trajectory to an individual off-file.
+ */
+ void exportTrajectories() {
+ Eigen::MatrixX3d mat;
+ for (int i = 0; i < p_cannonBallSim->getNumTrajectories(); i++) {
+ string filename = "trajectory" + to_string(i) + ".off";
+ p_cannonBallSim->getTrajectories(i, mat);
+ if (mat.rows() <= 1) {
+ continue;
+ }
+ if (igl::writeOFF(filename, mat, Eigen::MatrixXi())) {
+ cout << "Wrote trajectory to " << filename << endl;
+ } else {
+ cout << "Failed to write trajectory to " << filename << endl;
+ }
+ }
+ }
+
+ virtual void drawSimulationParameterMenu() override {
+ if (ImGui::Button("Export Trajectories", ImVec2(-1, 0))) {
+ exportTrajectories();
+ }
+ ImGui::SliderAngle("Angle", &m_angle, -180.0f, 180.0f);
+ ImGui::InputFloat("Force", &m_force, 0, 0);
+ ImGui::InputFloat("Mass", &m_mass, 0, 0);
+ ImGui::InputFloat("dt", &m_dt, 0, 0);
+ ImGui::Combo("Integrator", &m_selected_integrator, m_integrators.data(),
+ m_integrators.size());
+ ImGui::InputInt("Log Frequency", &m_log_frequency, 0, 0);
+ }
+};
+
+int main(int argc, char *argv[]) {
+ // create a new instance of the GUI for the cannonball simulation
+ new CannonBallGui();
+
+ return 0;
+}
\ No newline at end of file
diff --git a/1-2_spring/CMakeLists.txt b/1-2_spring/CMakeLists.txt
new file mode 100644
index 0000000..6050d05
--- /dev/null
+++ b/1-2_spring/CMakeLists.txt
@@ -0,0 +1,43 @@
+
+cmake_minimum_required(VERSION 3.1)
+project(1-2_spring)
+
+set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CMAKE_CURRENT_SOURCE_DIR}/../cmake)
+set(CMAKE_CXX_FLAGS "-Wall")
+
+# libigl
+option(LIBIGL_USE_STATIC_LIBRARY "Use libigl as static library" OFF)
+option(LIBIGL_WITH_ANTTWEAKBAR "Use AntTweakBar" OFF)
+option(LIBIGL_WITH_CGAL "Use CGAL" OFF)
+option(LIBIGL_WITH_COMISO "Use CoMiso" OFF)
+option(LIBIGL_WITH_CORK "Use Cork" OFF)
+option(LIBIGL_WITH_EMBREE "Use Embree" OFF)
+option(LIBIGL_WITH_LIM "Use LIM" OFF)
+option(LIBIGL_WITH_MATLAB "Use Matlab" OFF)
+option(LIBIGL_WITH_MOSEK "Use MOSEK" OFF)
+option(LIBIGL_WITH_OPENGL "Use OpenGL" ON)
+option(LIBIGL_WITH_OPENGL_GLFW "Use GLFW" ON)
+option(LIBIGL_WITH_OPENGL_GLFW_IMGUI "Use ImGui" ON)
+option(LIBIGL_WITH_PNG "Use PNG" OFF)
+option(LIBIGL_WITH_PYTHON "Use Python" OFF)
+option(LIBIGL_WITH_TETGEN "Use Tetgen" OFF)
+option(LIBIGL_WITH_TRIANGLE "Use Triangle" OFF)
+option(LIBIGL_WITH_VIEWER "Use OpenGL viewer" ON)
+option(LIBIGL_WITH_XML "Use XML" OFF)
+
+if (NOT LIBIGL_FOUND)
+ find_package(LIBIGL REQUIRED QUIET)
+endif()
+
+# Add default project files
+file(GLOB LIBFILES ${PROJECT_SOURCE_DIR}/../include/*.*)
+source_group("Library Files" FILES ${LIBFILES})
+include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../include)
+
+# Add your project files
+file(GLOB SRCFILES *.cpp)
+file(GLOB HFILES *.h)
+
+add_definitions(-DIGL_VIEWER_VIEWER_QUIET)
+add_executable(${PROJECT_NAME} ${SRCFILES} ${HFILES} ${LIBFILES} )
+target_link_libraries(${PROJECT_NAME} igl::core igl::opengl_glfw igl::opengl_glfw_imgui)
\ No newline at end of file
diff --git a/1-2_spring/SpringSim.cpp b/1-2_spring/SpringSim.cpp
new file mode 100644
index 0000000..9219f8b
--- /dev/null
+++ b/1-2_spring/SpringSim.cpp
@@ -0,0 +1,50 @@
+#include "SpringSim.h"
+
+bool SpringSim::advance() {
+ // perform time integration with different integrators
+
+ // use p_cube, m_spring, m_dt, m_gravity
+
+ Eigen::Vector3d v = p_cube->getLinearVelocity();
+ Eigen::Vector3d p = p_cube->getPosition();
+
+ // TODO
+
+ // note that it is required to update both m_sptring.end and p_cube's position
+ switch (m_method) {
+ case 0: // analytical solution
+ {
+ break;
+ }
+ case 1: // explicit euler
+
+ break;
+
+ case 2: // symplectic euler
+
+ break;
+
+ case 3: // midpoint
+
+ break;
+
+ default:
+ std::cerr << m_method << " is not a valid integrator method."
+ << std::endl;
+ }
+
+ // update spring end position
+ m_spring.end = p_cube->getPosition();
+
+
+ // advance m_time
+ m_time += m_dt;
+ m_step++;
+
+ // log
+ if ((m_step % m_log_frequency) == 0) {
+ m_trajectories.back().push_back(p_cube->getPosition());
+ }
+
+ return false;
+}
\ No newline at end of file
diff --git a/1-2_spring/SpringSim.h b/1-2_spring/SpringSim.h
new file mode 100644
index 0000000..b487980
--- /dev/null
+++ b/1-2_spring/SpringSim.h
@@ -0,0 +1,154 @@
+#include "Simulation.h"
+
+using namespace std;
+
+struct Spring {
+ public:
+ float stiffness;
+ float length;
+ float damping;
+ Eigen::Vector3d start;
+ Eigen::Vector3d end;
+};
+
+/*
+ * Simulation of a string with an attached mass.
+ */
+class SpringSim : public Simulation {
+public:
+ SpringSim() : Simulation() {
+ init();
+ m_trajectories.clear();
+ m_trajectoryColors.clear();
+ }
+
+ virtual void init() override {
+ std::string path = "cube.off";
+ m_objects.clear();
+ m_objects.push_back(RigidObject(path));
+ p_cube = &m_objects.back();
+
+ m_dt = 1e-2;
+ m_mass = 1.0;
+ m_log_frequency = 30;
+ m_method = 0;
+ m_gravity << 0, -9.81, 0;
+
+ reset();
+ }
+
+ virtual void resetMembers() override {
+ p_cube->reset();
+ m_spring.end = m_spring.start - m_spring.length * Eigen::Vector3d(0, 1, 0);
+ p_cube->setPosition(m_spring.end);
+ p_cube->setMass(m_mass);
+
+ if (m_trajectories.size() == 0 || m_trajectories.back().size() > 1) {
+ m_trajectories.push_back(vector<Eigen::Vector3d>());
+ m_trajectoryColors.push_back(m_color);
+ } else {
+ m_trajectoryColors.back() = m_color;
+ }
+
+ setMethod(m_method);
+ }
+
+ virtual void updateRenderGeometry() override {
+ p_cube->getMesh(m_renderV, m_renderF);
+ }
+
+ virtual bool advance() override;
+
+ virtual void renderRenderGeometry(
+ igl::opengl::glfw::Viewer &viewer) override {
+ viewer.data().set_mesh(m_renderV, m_renderF);
+
+ for (size_t trajectory = 0; trajectory < m_trajectories.size();
+ trajectory++) {
+ for (size_t point = 0; point < m_trajectories[trajectory].size();
+ point++) {
+ viewer.data().add_points(
+ m_trajectories[trajectory][point].transpose(),
+ m_trajectoryColors[trajectory]);
+ }
+ }
+
+ // draw the spring
+ for (int i = 0; i < 20; ++i) {
+ double w = i / 20.0;
+ Eigen::RowVector3d p = m_spring.start * w + m_spring.end * (1 - w);
+ viewer.data().add_points(p, Eigen::RowVector3d(0, 0, 0));
+ }
+ }
+
+ void clearTrajectories() {
+ m_trajectories.clear();
+ m_trajectories.push_back(vector<Eigen::Vector3d>());
+ m_trajectoryColors.clear();
+ m_trajectoryColors.push_back(m_color);
+ }
+
+#pragma region SettersAndGetters
+ void setMass(double m) { m_mass = m; }
+
+ void setSpring(const Spring &s) {
+ m_spring = s;
+ m_spring.end =
+ m_spring.start - m_spring.length * Eigen::Vector3d(0, 1, 0);
+ p_cube->setPosition(m_spring.end);
+ }
+
+ void setMethod(int m) {
+ m_method = m;
+ switch (m_method) {
+ case 0:
+ m_color = Eigen::RowVector3d(1.0, 0.0, 0.0);
+ break;
+ case 1:
+ m_color = Eigen::RowVector3d(0.0, 1.0, 0.0);
+ break;
+ case 2:
+ m_color = Eigen::RowVector3d(0.0, 0.0, 1.0);
+ break;
+ case 3:
+ m_color = Eigen::RowVector3d(1.0, 1.0, 0.0);
+ break;
+ default:
+ std::cerr << m_method << " is not a valid integrator method."
+ << std::endl;
+ }
+ if (m_step == 0) {
+ m_trajectoryColors.back() = m_color;
+ }
+ }
+
+ void setLogFrequency(int f) { m_log_frequency = f; }
+
+ void getTrajectories(int index, Eigen::MatrixX3d &mat) const {
+ int num_points = m_trajectories[index].size();
+ mat.resize(num_points, 3);
+ for (int i = 0; i < num_points; i++) {
+ mat.row(i) = m_trajectories[index][i];
+ }
+ }
+
+ int getNumTrajectories() const { return m_trajectories.size(); }
+#pragma endregion SettersAndGetters
+
+private:
+ int m_method; // id of integrator to be used (0: analytical, 1: explicit euler, 2: semi-implicit euler, 3: midpoint)
+ double m_mass;
+
+ Eigen::Vector3d m_gravity;
+
+ Spring m_spring;
+ RigidObject *p_cube;
+
+ Eigen::MatrixXd m_renderV; // vertex positions for rendering
+ Eigen::MatrixXi m_renderF; // face indices for rendering
+
+ int m_log_frequency; // how often should we log the COM in the GUI
+ vector<vector<Eigen::Vector3d>> m_trajectories;
+ Eigen::RowVector3d m_color;
+ vector<Eigen::RowVector3d> m_trajectoryColors;
+};
\ No newline at end of file
diff --git a/1-2_spring/main.cpp b/1-2_spring/main.cpp
new file mode 100644
index 0000000..10699bc
--- /dev/null
+++ b/1-2_spring/main.cpp
@@ -0,0 +1,123 @@
+#include <igl/writeOFF.h>
+#include <thread>
+#include "Gui.h"
+#include "Simulator.h"
+#include "SpringSim.h"
+
+/*
+ * GUI for the spring simulation. This time we need additional paramters,
+ * e.g. which integrator to use for the simulation and the force applied to the
+ * cube, and we also add some more visualizations (trajectories).
+ */
+class SpringGui : public Gui {
+ public:
+ // simulation parameters
+ float m_dt = 1e-2;
+ float m_mass = 1.0;
+ int m_log_frequency = 30;
+
+ Spring m_spring; // stores properties of a spring
+
+ SpringSim *p_springSim = NULL;
+
+ const vector<char const *> m_integrators = {"Analytic", "Explicit Euler", "Symplectic Euler", "Midpoint"};
+ int m_selected_integrator = 0;
+
+ SpringGui() {
+ // initialize the spring to be used
+ m_spring.length = 5.0;
+ m_spring.stiffness = 5.0;
+ m_spring.damping = 0.1;
+ m_spring.start = m_spring.end = Eigen::Vector3d::Zero();
+
+ p_springSim = new SpringSim();
+ p_springSim->setSpring(m_spring);
+ setSimulation(p_springSim);
+
+ // show vertex velocity instead of normal
+ callback_clicked_vertex =
+ [&](int clickedVertexIndex, int clickedObjectIndex,
+ Eigen::Vector3d &pos, Eigen::Vector3d &dir) {
+ RigidObject &o = p_springSim->getObjects()[clickedObjectIndex];
+ pos = o.getVertexPosition(clickedVertexIndex);
+ dir = o.getVelocity(pos);
+ };
+ start();
+ }
+
+ virtual void updateSimulationParameters() override {
+ // change all parameters of the simulation to the values that are set in
+ // the GUI
+ p_springSim->setTimestep(m_dt);
+ p_springSim->setMethod(m_selected_integrator);
+ p_springSim->setLogFrequency(m_log_frequency);
+ p_springSim->setMass(m_mass);
+ p_springSim->setSpring(m_spring);
+ }
+
+ virtual void clearSimulation() override {
+ p_springSim->clearTrajectories();
+ }
+
+ /*
+ * Writes each trajectory to an individual off-file.
+ */
+ void exportTrajectories() {
+ Eigen::MatrixX3d mat;
+ for (int i = 0; i < p_springSim->getNumTrajectories(); i++) {
+ string filename = "trajectory" + to_string(i) + ".off";
+ p_springSim->getTrajectories(i, mat);
+ if (mat.rows() <= 1) {
+ continue;
+ }
+ if (igl::writeOFF(filename, mat, Eigen::MatrixXi())) {
+ cout << "Wrote trajectory to " << filename << endl;
+ } else {
+ cout << "Failed to write trajectory to " << filename << endl;
+ }
+ }
+ }
+
+ virtual bool childKeyCallback(igl::opengl::glfw::Viewer &viewer,
+ unsigned int key, int modifiers) override {
+ switch (key) {
+ case 'e':
+ case 'E':
+ exportTrajectories();
+ return true;
+ // cicle through different integrators
+ case '>':
+ m_selected_integrator++;
+ m_selected_integrator %= m_integrators.size();
+ return true;
+ case '<':
+ m_selected_integrator--;
+ m_selected_integrator =
+ (m_integrators.size() + m_selected_integrator) %
+ m_integrators.size();
+ return true;
+ }
+ return false;
+ }
+
+ virtual void drawSimulationParameterMenu() override {
+ if (ImGui::Button("Export Trajectories", ImVec2(-1, 0))) {
+ exportTrajectories();
+ }
+ ImGui::InputFloat("Spring Stiffness", &m_spring.stiffness, 0, 0);
+ ImGui::InputFloat("Spring Length", &m_spring.length, 0, 0);
+ ImGui::InputFloat("Mass", &m_mass, 0, 0);
+ ImGui::InputFloat("Damping", &m_spring.damping, 0, 0);
+ ImGui::InputFloat("dt", &m_dt, 0, 0);
+ ImGui::Combo("Integrator", &m_selected_integrator, m_integrators.data(),
+ m_integrators.size());
+ ImGui::InputInt("Log Frequency", &m_log_frequency, 0, 0);
+ }
+};
+
+int main(int argc, char *argv[]) {
+ // create a new instance of the GUI for the spring simulation
+ new SpringGui();
+
+ return 0;
+}
\ No newline at end of file
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 84afcec..54f8925 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -27,4 +27,7 @@ if (NOT LIBIGL_FOUND)
find_package(LIBIGL REQUIRED QUIET)
endif()
-add_subdirectory(0_dummy)
\ No newline at end of file
+# add_subdirectory(0_dummy)
+add_subdirectory(1-0_earth)
+add_subdirectory(1-1_cannonball)
+add_subdirectory(1-2_spring)
\ No newline at end of file
diff --git a/include/Simulation.h b/include/Simulation.h
index 04e80ac..bb839c3 100644
--- a/include/Simulation.h
+++ b/include/Simulation.h
@@ -43,6 +43,7 @@ public:
* touch any rendering data structures at all). You have to update the time
* variables at the end of each step if they are necessary for your
* simulation.
+ * Return true means the simulation is finished.
*/
virtual bool advance() = 0;
--
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