Here is what I typed:

$ mkdir build
$ cd build
$ cmake -DCMAKE_BUILD_TYPE=Release ..
-- GCC >= 4.9 detected, enabling colored diagnostics
-- Third-party: creating target 'Eigen3::Eigen'
-- Third-party: creating target 'igl::core'
-- Creating target: igl::core (igl)
-- Creating target: igl::opengl (igl_opengl)
-- Creating target: igl::opengl_glfw (igl_opengl_glfw)
-- Using X11 for window creation
-- Creating target: igl::opengl_glfw_imgui (igl_opengl_glfw_imgui)
-- Creating target: igl::png (igl_png)
-- Creating target: igl::predicates (igl_predicates)
-- Third-party: creating target 'nlohmann::json'
-- Third-party: creating target 'spdlog::spdlog'
-- Build spdlog: 1.9.0
-- Build type: Release
-- Generating install
-- Third-party: creating target 'finitediff::finitediff'
-- Third-party: creating targets 'Boost::boost'
-- Fetching Boost
-- Fetching Boost - done
-- Boost found: 1.71.0 /home/glenn/src/github.com/ipc-sim/rigid-ipc/build/_deps/boost-src
-- Found the following ICU libraries:
--   uc (required)
--   dt (required)
--   i18n (required)
-- Third-party: creating target 'TBB::tbb'
-- Third-party: creating target 'tight_inclusion::tight_inclusion'
-- Tight-Inclusion CCD bottom-level project
-- GCC >= 4.9 detected, enabling colored diagnostics
-- Searching for AVX...
-- Using CPU native flags for AVX optimization:  -march=native
--   Found AVX 2.0 extensions, using flags:  -march=native -mavx2 -mno-avx512f -mno-avx512pf -mno-avx512er -mno-avx512cd
-- Using Double Precision Floating Points
-- Third-party: creating target 'PolyFEM::polysolve'
[ 11%] Performing download step (git clone) for 'polysolve-populate'
Cloning into 'polysolve-src'...
fatal: reference is not a tree: a94e9b8ed8302d4b479533c67419f31addb1e987
CMake Error at polysolve-subbuild/polysolve-populate-prefix/tmp/polysolve-populate-gitclone.cmake:40 (message):
  Failed to checkout tag: 'a94e9b8ed8302d4b479533c67419f31addb1e987'


CMakeFiles/polysolve-populate.dir/build.make:110: recipe for target 'polysolve-populate-prefix/src/polysolve-populate-stamp/polysolve-populate-download' failed
make[2]: *** [polysolve-populate-prefix/src/polysolve-populate-stamp/polysolve-populate-download] Error 1
CMakeFiles/Makefile2:94: recipe for target 'CMakeFiles/polysolve-populate.dir/all' failed
make[1]: *** [CMakeFiles/polysolve-populate.dir/all] Error 2
Makefile:102: recipe for target 'all' failed
make: *** [all] Error 2

CMake Error at /usr/local/cmake-3.18.2-Linux-x86_64/share/cmake-3.18/Modules/FetchContent.cmake:987 (message):
  Build step for polysolve failed: 2
Call Stack (most recent call first):
  /usr/local/cmake-3.18.2-Linux-x86_64/share/cmake-3.18/Modules/FetchContent.cmake:1082:EVAL:2 (__FetchContent_directPopulate)
  /usr/local/cmake-3.18.2-Linux-x86_64/share/cmake-3.18/Modules/FetchContent.cmake:1082 (cmake_language)
  /usr/local/cmake-3.18.2-Linux-x86_64/share/cmake-3.18/Modules/FetchContent.cmake:1125 (FetchContent_Populate)
  cmake/recipes/polysolve.cmake:14 (FetchContent_MakeAvailable)
  CMakeLists.txt:225 (include)


-- Configuring incomplete, errors occurred!
See also "/home/glenn/src/github.com/ipc-sim/rigid-ipc/build/CMakeFiles/CMakeOutput.log".
See also "/home/glenn/src/github.com/ipc-sim/rigid-ipc/build/CMakeFiles/CMakeError.log".

Any ideas how to fix this? It looks like a bad git reference in polysolve-src, possibly.

Thank you!

I tried some of the examples in the "fixtures" directory, and the simulator works great! Nice work!

However, I discovered that there are some examples that don't run either because their mesh files don't exist in the repo or because of some other problem.

For example, this example is missing its meshes: https://github.com/ipc-sim/rigid-ipc/blob/main/fixtures/3D/mechanisms/expanding-lock-box.json#L11-L57

This example says [2021-09-30 19:57:28.039] [error] Invalid Json file: https://github.com/ipc-sim/rigid-ipc/blob/main/fixtures/2D/compactor.json

Updated clang-format so long chains of parameters are shown one on each line (don't hate me)

IO

• Added rigid-body fixtures (NEW FORMAT!)
  • Added rigid-body reader
• Added json/eigen helper to read/write matrices

OPT

• Added is_barrier method (and get/set epsilon) to CollisionConstraint so we don't need to pass the BarrierConstraint to the solver
  • Updated barrier constraint to use them
• Added accessors on OptimizationProblem for barrier case
  • updated ad-hoc problem too since it was used on unit-tests

PHYSICS

• updated RigidBody class to

  • include theta: position is now length 3 (x, y, theta)
  • compute mass and moment of intertia (needed for forces)
  • added position of previous step
  • added differentiable world vertices, and flag to obtain the vertices of the current or previous step.
  • TODO: remove world_displacements, we should use world_vertices instead!

• Added RigidBodyAssembler (to replace RigidBodyAssembler once finished)

  • init method only computes inmmutable information
  • other methods compute assembly on call

SIMULATION

• Added new main file for simulation
• Added UISimSate and UIMenu for the simulation UI
• TODO: merge with collision-debugging UI or add export of single problematic step

I updated the Newton solver to fail to gradient descent if the line search fails. This helps the optimization make progress even when the Hessian is ill-conditioned. The next step after this pull request is merged is to add a quasi-Newton solver (e.g. BFGS).

• Exposed initialization of barrier epsilon in the UI.
• Separated line search into its own file.
• Newton method now fails to gradient descent.

Refactor structure of project. Now we have only 4 problems

• Rigid Body Physics + Distance Barrier Constraint + Barrier Solver

• Particles Physics + Distance Barrier Constraint + Barrier Solver

• Rigid Body Physics + Volume Constraint + NCP Solver

• Particles Physics + Volume Constraint + NCP Solver

• Remove some base classes that were forcing us to write more functions than neccesary

  • Base OptimizationProblem is gone, now we have some interfaces for the different problems
  • Base CollisionConstraint remainds but implements few methods.

• Removed exmplicit template instantiation and instead created .tpp files to keep template implementations

• Exposed broad-phase in order to get the candidate collisions
• Modified DistanceBarrier::detectCollisions to first build a common collision candidate set
• Using this set run the narrow-phase of both the barrier and the CCD
• TODO: Expose the ev_candidates as a member variable.
• TODO: Add a is_collision_candidates_frozen flag to cause detectCollisions to not run the broad-phase again.

• Added BFGS and GD to barrier solver as inner solvers
• Needed to move some functionality out of NewtonSolver and into OptimizationSolvers
• TODO: Move free_dof out of the OptimizationSolver and into the optimization problem with the eval_* functions using free_dof to remove elements.

• Added python notebook to get exact derivatives of RB transformation
• Moved rigid body to its own file (out of rigid_body_system)
  • Added tests for RB gradient/hessian comparing with exact solutions
• Added assembly of gradient and hessian on RB-System
  • Added test for RB-System comparing with exact solutions

Added Rigid Body Problem

• Added Rigid Body Problem to opt/
• Implemented Functional, its gradient and hessian
  • tested against finite differences
• Added tensor util to compute the multiplication of (1x2N) * (2N x 3B x 3B) used by the chain rule.

• Moved rigid bodies to physics/ folder
  • added RigidBodySystem that keeps list of RB.
• Moved solvers to solvers/ folder
• Removed (a lot of)unused code

Add UI features for controlling rigid bodies individually

• Added gradient and hessian of compute_particle_displacements
  • This will be removed later it not used
• Improved readability by using .homogeneous and .hnormalized
• Edit buttons half width
• Rigid body section to control the velocity of each body
• State method to update the displacements and other fields from the rigid bodies

The menu loads the one-link fixture file and duplicates the link n times. Each link has a scaled displacement, so all links have at least one contact.

Hi, I git clone the rigid-ipc, and use python build.py to compile the project.

It gives this error: CMake Error at python/CMakeLists.txt:6 (rigid_ipc_download_project): Unknown CMake command "rigid_ipc_download_project". Call Stack (most recent call first): python/CMakeLists.txt:13 (rigid_ipc_download_pybind11)

my cmake version is 3.16.3 os: ubuntu 20.04 python: miniconda with python 3.7

BTW, I also tried with:

mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release ..
make

This can make with no mistakes.

I think something wrong with the python part? Any suggestions? Thanks!