Added Assm library code (Adaptive Screen Space Meshing.

Removed dependencies on python, openmp, opencv, torch etc.
A simple rasterizer and a gaussian blur implementation replaces them.

Author: ponchio

external/assm/CMakeLists.txt

@@ -0,0 +1,19 @@
+cmake_minimum_required(VERSION 3.19 FATAL_ERROR)
+project(ASSM VERSION 1.0.0 LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+find_package (Eigen3)
+if(NOT Eigen3_FOUND)
+	set(EIGEN3_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../eigen-3.3.9)
+	
+endif()
+
+include_directories(${EIGEN3_INCLUDE_DIR})
+
+file(GLOB SOURCES ./*.cpp ./algorithms/*.cpp)
+file(GLOB HEADERS ./*.h ./algorithms/*.h)
+
+add_library(assm ${SOURCES} ${HEADERS})
+

external/assm/Exceptions.h

@@ -0,0 +1,57 @@
+// Copyright 2021 the Polygon Mesh Processing Library developers.
+// Distributed under a MIT-style license, see LICENSE.txt for details.
+
+#pragma once
+
+#include <stdexcept>
+
+namespace pmp {
+
+//! \addtogroup core
+//! @{
+
+//! \brief Exception indicating invalid input passed to a function.
+//! \details This exception should be used to signal violation of a
+//! precondition, e.g., if an algorithm expects a pure triangle mesh but a
+//! general polygon mesh is passed instead.
+class InvalidInputException : public std::invalid_argument
+{
+public:
+	InvalidInputException(const std::string& what) : std::invalid_argument(what)
+	{
+	}
+};
+
+//! \brief Exception indicating failure so solve an equation system.
+class SolverException : public std::runtime_error
+{
+public:
+	SolverException(const std::string& what) : std::runtime_error(what) {}
+};
+
+//! \brief Exception indicating failure to allocate a new resource.
+//! \details This exception signals an error resulting from an attempt to exceed
+//! implementation-defined allocation limits.
+class AllocationException : public std::length_error
+{
+public:
+	AllocationException(const std::string& what) : std::length_error(what) {}
+};
+
+//! \brief Exception indicating a topological error has occurred.
+class TopologyException : public std::logic_error
+{
+public:
+	TopologyException(const std::string& what) : std::logic_error(what) {}
+};
+
+//! \brief Exception indicating an error occurred while performing IO.
+class IOException : public std::runtime_error
+{
+public:
+	IOException(const std::string& what) : std::runtime_error(what) {}
+};
+
+//! @}
+
+} // namespace pmp