Upgrade proj to 9.5.0 and include dockerfile for reproducible builds

.gitignore

@@ -16,3 +16,4 @@
 .idea/workspace.xml
 .idea/encodings.xml
 output/
+build/

DEVELOPMENT.md

@@ -0,0 +1,184 @@
+# Go Cesium Tiler - Development
+
+```
+                                             _   _ _
+  __ _  ___   ___ ___  ___(_)_   _ _ __ ___ | |_(_) | ___ _ __
+ / _  |/ _ \ / __/ _ \/ __| | | | | '_   _ \| __| | |/ _ \ '__|
+| (_| | (_) | (_|  __/\__ \ | |_| | | | | | | |_| | |  __/ |
+ \__, |\___/ \___\___||___/_|\__,_|_| |_| |_|\__|_|_|\___|_|
+  __| | A Cesium Point Cloud tile generator written in golang
+ |___/ 
+```
+
+## Introduction
+With the release of version 2, in particular from version 2.0.0-gamma, gocesiumtiler uses the Proj v9.5+ library to perform coordinate conversions. As a result, building the executable is more complex due to the need for `cgo` compiling, but also the need of statically building and linking Proj with the go executable.
+
+The build environment thus needs to be properly setup to enable the builds.
+
+## Reproducible builds powered by Docker
+In order to streamline the build steps, reproducible builds are achieved through a Dockerfile. The repository contains three files:
+- `Dockerfile`: Contains all the build steps needed to build and test gocesiumtiler in both Windows and Linux.
+- `build.sh`: Kickstarts the docker build process injecting the right arguments.
+- `build.ps1`: Powershell scripts that works as `build.sh` but meant to be used with powershell under a windows environment.
+
+The Dockerfile is organized as a multi-stage build.
+1. A base image is prepared, containing essential build tools.
+2. A linux build image is created, where the required dependencies to build under linux are pulled and compiled. Proj is rebuilt from the sources with static linking  targeting the Linux OS and then gocesiumtiler is compiled linking it to the static version of the Proj library.
+3. Another linux build image is created, this one pulling the dependencies needed to cross-compile the gocesiumtiler executable under Windows. Proj is rebuilt again, this time targeting the Windows x86-64 architecture.
+4. The build artifacts are copied in a final scratch image where they are ready to be copied out to the host.
+
+## Local Development environment setup
+Two approaches are possible, using docker to run builds in a reproducible environment or building it locally setting up the local machine.
+
+Note that all the options mentioned statically link Proj to the final build executable, this ensures the system builds a single highly portable binary that embeds all required dependencies. 
+
+### Option 1. Install docker and use `build.sh` or `build.ps1` to build the code and run the tests. 
+
+The pro here is that this should work in any environment and ensures that the final executable build is reproducible. It recommended to always run a "dockerized" build before creating a PR.
+
+To build just run in a powershell console:
+```
+./build.ps1
+```
+
+### Option 2. Setup the local machine for local development without Docker.
+
+This approach is more challenging and the steps are different depending whether you are development under Windows or Linux. In general the environment needs to be set up mimicking the steps described in the `Dockerfile`. 
+
+Since the dockerfile has been written designed to run builds in Linux, that is also documenting how to setup a linux dev environment. In the following we will focus mostly instead on the steps to setup a dev environment under Windows.
+
+### **Setup a Windows development environment**
+The commands in the following are supposed to be executed from a powershell console.
+
+**1. Install golang**
+
+**2. Install msys2**
+
+Msys2 will be used to install build tools like the Mingw64 compiler, CMake and Pkgconfig.
+Install it following the instructions here https://www.msys2.org/#installation or using Chocolatey.
+
+Make sure the `bin` folder is available on the `Path`. The `Path` should contain 
+the following folder (please adapt them according to where your Msys2 installation is located):
+- `C:\msys64\usr\bin`
+
+**3. Use Msys2 package manager pacman to install the required build tools**
+
+```
+pacman -S --noconfirm mingw-w64-x86_64-pkgconf
+pacman -S --noconfirm mingw-w64-x86_64-gcc
+pacman -S --noconfirm mingw-w64-x86_64-cmake
+pacman -S --noconfirm mingw-w64-x86_64-sqlite3
+```
+
+Make sure that mingw64 executable is on the `Path` and if not add it manually, i.e. add :
+```
+C:\msys64\mingw64\bin
+```
+to the path.
+
+**4. Install `Vcpkg`, used to manage the dependencies**
+
+[vcpkg](https://vcpkg.io/en/) is a free C/C++ package manager that will greatly simplify the build setup. To install typically just clone the git repository in some folder, eg:
+```
+git clone https://github.com/Microsoft/vcpkg.git "C:\vcpkg"
+```
+
+And then run:
+```
+cd C:\vcpkg
+bootstrap-vcpkg.bat -disableMetrics
+```
+
+**5. Set the default Triplets for Vcpkg by creating / setting these environment variables**
+
+- `VCPKG_DEFAULT_TRIPLET`=`x64-mingw-static`
+- `VCPKG_DEFAULT_HOST_TRIPLET` = `x64-mingw-static`
+
+**6. Install the dependencies needed to build the Proj library (sqlite3 and tiff) via `vcpkg.exe`**
+
+```
+vcpkg.exe install sqlite3[core,tool] zlib --triplet=x64-mingw-static
+```
+
+Note, we are building a statically linked version of these libraries.
+
+**7. Clone Proj in some folder, eg `C:\proj`**
+
+```
+git clone https://github.com/OSGeo/PROJ.git  "C:\proj"
+```
+
+If you want a specific version of Proj instead download and uncompress the archive from
+```
+https://download.osgeo.org/proj/$PROJ_VERSION.tar.gz
+```
+
+where `$PROJ_VERSION` is the name of the version you want, e.g. `proj-9.5.0`
+
+**8. Build PROJ with static linking**
+
+```
+cd C:\proj
+mkdir build
+cd build
+cmake -DCMAKE_TOOLCHAIN_FILE=C:\vcpkg\scripts\buildsystems\vcpkg.cmake `
+    -DVCPKG_TARGET_TRIPLET=x64-mingw-static `
+    -DCMAKE_C_COMPILER=x86_64-w64-mingw32-gcc `
+    -DCMAKE_CXX_COMPILER=x86_64-w64-mingw32-g++ `
+    -DCMAKE_INSTALL_PREFIX=/usr/local/ `
+    -DCMAKE_BUILD_TYPE=Release `
+    -DBUILD_APPS=OFF `
+    -DBUILD_SHARED_LIBS=OFF `
+    -DENABLE_CURL=OFF `
+    -DENABLE_TIFF=ON `
+    -DEMBED_PROJ_DATA_PATH=OFF `
+    -DBUILD_TESTING=OFF .. 
+cmake --build . --config Release -j $(nproc)
+cmake --build . --target install -j $(nproc)
+```
+
+Make sure `which cmake` points to the Msys2 - Mingw64 installation folder. If `$(nproc)` doesn't work just replace it with the number of CPUs on your system.
+
+---
+
+**Note: Steps 1-8 are only required to be executed once, or when you want to upgrade the Proj version or one of its dependencies.**
+
+---
+
+**9. Build gocesiumtiler**
+
+This requires some tinkering, depending on your development configuration you might have to tune parameters like the linker search path or the `PKG_CONFIG_PATH`.
+
+The following is a general guide of a configuration that could work: 
+```
+$env:PKG_CONFIG_PATH="C:\usr\local\lib\pkgconfig;C:\vcpkg\installed\x64-mingw-static\lib\pkgconfig"; `
+$env:CC="x86_64-w64-mingw32-gcc"; `
+$env:CGO_ENABLED=1; `
+$env:CGO_LDFLAGS="-L/vcpkg/installed/x64-mingw-static/lib -g -O2 -static -lstdc++ -lsqlite3 -ltiff -lzlib -ljpeg -llzma -lm"; `
+go build -o ./bin/gocesiumtiler.exe ./cmd/main.go
+```
+
+To run the tests similarly run:
+```
+$env:PKG_CONFIG_PATH="C:\usr\local\lib\pkgconfig;C:\vcpkg\installed\x64-mingw-static\lib\pkgconfig"; `
+$env:CC="x86_64-w64-mingw32-gcc"; `
+$env:CGO_ENABLED=1; `
+$env:CGO_LDFLAGS="-L/vcpkg/installed/x64-mingw-static/lib -g -O2 -static -lstdc++ -lsqlite3 -ltiff -lzlib -ljpeg -llzma -lm"; `
+go test -v ./...
+```
+
+Of course the environment variables `PKG_CONFIG_PATH`, `CC`, `CGO_ENABLED`, `CGO_LDFLAGS` could also be stored permanently in the environment configuration so that the build and test commands become trivial:
+
+```
+go build -o ./bin/gocesiumtiler.exe ./cmd/main.go
+```
+
+and
+
+```
+go test v ./...
+```
+
+### **Setup a Linux development environment**
+
+Please refer to the Dockerfile where the commands to setup a dev environment for Ubuntu-based development environment are listed in detail.

Dockerfile

@@ -0,0 +1,164 @@
+##################################
+#        BASE BUILD IMAGE        #
+##################################
+FROM ubuntu:latest AS builder-base
+
+# Change these two arguments to change the version of go and PROJ
+ARG GO_VERSION="1.23.2"
+ARG PROJ_VERSION="proj-9.5.0"
+
+# build variable, no impact on the final artifacts
+ARG PROJECT_FOLDER="/usr/src/gocesiumtiler"
+
+# install essential tools
+# partly taken from https://github.com/OSGeo/PROJ/blob/master/Dockerfile
+RUN apt-get update
+RUN DEBIAN_FRONTEND=noninteractive apt-get install -y --fix-missing --no-install-recommends \
+    apt-transport-https software-properties-common ca-certificates wget zip unzip curl tar pkg-config \
+    git cmake make sqlite3 libsqlite3-dev \
+    && apt-get clean && rm -rf /var/lib/apt/lists/*
+
+# install powershell, required for vcpkg 
+# taken from https://learn.microsoft.com/en-us/powershell/scripting/install/install-ubuntu?view=powershell-7.4
+RUN . /etc/os-release && wget -q "https://packages.microsoft.com/config/ubuntu/$VERSION_ID/packages-microsoft-prod.deb"
+RUN dpkg -i packages-microsoft-prod.deb
+RUN rm packages-microsoft-prod.deb
+RUN apt-get update
+RUN apt-get install -y powershell
+RUN apt-get clean && rm -rf /var/lib/apt/lists/*
+
+# install vcpkg to manage packages and dependencies
+WORKDIR /vcpkg
+RUN git clone https://github.com/Microsoft/vcpkg.git "/vcpkg"
+RUN ./bootstrap-vcpkg.sh -disableMetrics
+
+# clone proj
+WORKDIR ${PROJECT_FOLDER}
+RUN wget -c https://download.osgeo.org/proj/$PROJ_VERSION.tar.gz
+RUN tar -xvzf $PROJ_VERSION.tar.gz
+RUN mkdir $PROJ_VERSION/build
+
+# install golang (taken from https://go.dev/doc/install)
+WORKDIR /tmp
+RUN wget https://go.dev/dl/go$GO_VERSION.linux-amd64.tar.gz
+RUN rm -rf /usr/local/go && tar -C /usr/local -xzf go$GO_VERSION.linux-amd64.tar.gz
+ENV PATH="/usr/local/go/bin:${PATH}" 
+
+##################################
+#       LINUX X64 BUILDER        #
+##################################
+FROM builder-base AS linux-builder
+# install build tools for linux x64 compilation 
+RUN apt-get update
+RUN DEBIAN_FRONTEND=noninteractive apt-get install -y --fix-missing --no-install-recommends build-essential
+
+# install proj dependencies for linux x64
+RUN /vcpkg/vcpkg install sqlite3[core,tool] tiff --triplet=x64-linux
+
+# build proj statically for linux x64
+WORKDIR ${PROJECT_FOLDER}/${PROJ_VERSION}/build
+RUN cmake -DCMAKE_TOOLCHAIN_FILE=/vcpkg/scripts/buildsystems/vcpkg.cmake \
+          -DVCPKG_TARGET_TRIPLET=x64-linux \
+          -DCMAKE_INSTALL_PREFIX=/usr/local/ \
+          -DCMAKE_BUILD_TYPE=Release \
+          -DBUILD_APPS=OFF \
+          -DBUILD_SHARED_LIBS=OFF \
+          -DENABLE_CURL=OFF \
+          -DENABLE_TIFF=ON \
+          -DBUILD_TESTING=OFF .. \
+          -DEMBED_PROJ_DATA_PATH=OFF \ 
+          .. 
+RUN cmake --build . --config Release -j $(nproc)
+RUN cmake --build . --target install -j $(nproc)
+
+# BUILD_LABEL will force cache invalidation at every build if docker build is run with --build-arg BUILD_LABEL=$(date +%s) 
+RUN echo "$BUILD_LABEL"
+
+# clone the source and prepare the build dir
+WORKDIR ${PROJECT_FOLDER}/build
+COPY . .
+RUN mkdir -p ./bin
+
+# BUILD_ID will force cache invalidation at every build if docker build is run with eg --build-arg BUILD_ID=$(date +%s) 
+ARG BUILD_ID
+RUN echo "build id: $BUILD_ID"
+
+# build the go app for linux x64 statically using cgo
+RUN PKG_CONFIG_PATH="/vcpkg/installed/x64-linux/lib/pkgconfig" \
+    CGO_ENABLED=1 \
+    CGO_LDFLAGS='-L/vcpkg/installed/x64-linux/lib -g -O2 -static -lstdc++ -lsqlite3 -ltiff -lz -ljpeg -llzma -lm' \ 
+    go build -o ./bin/gocesiumtiler -ldflags "-X main.GitCommit=$(git rev-list -1 HEAD)" ./cmd/main.go
+
+# run the unit tests
+RUN PROJ_DATA="/usr/local/share/proj" \
+    PKG_CONFIG_PATH="/vcpkg/installed/x64-linux/lib/pkgconfig" \
+    CGO_ENABLED=1 \
+    CGO_LDFLAGS='-L/vcpkg/installed/x64-linux/lib -g -O2 -static -lstdc++ -lsqlite3 -ltiff -lz -ljpeg -llzma -lm' \ 
+    go test ./... -v
+
+
+##################################
+#      WINDOWS X64 BUILDER       #
+##################################
+FROM builder-base AS windows-builder
+# install mingw-w64 for cross-compilation to windows
+RUN apt-get update
+RUN DEBIAN_FRONTEND=noninteractive apt-get install -y --fix-missing --no-install-recommends mingw-w64 
+
+# set vcpkg env vars to force statically linked build using mingw x664
+ENV VCPKG_DEFAULT_TRIPLET=x64-mingw-static
+ENV VCPKG_DEFAULT_HOST_TRIPLET=x64-mingw-static
+
+# set cmake default compilers and env vars pointing them to mingw
+ENV CMAKE_C_COMPILER=x86_64-w64-mingw32-gcc
+ENV CMAKE_CXX_COMPILER=x86_64-w64-mingw32-g++
+ENV CMAKE_SYSTEM_NAME=Windows
+
+# install proj dependencies
+RUN /vcpkg/vcpkg install sqlite3[core,tool] tiff --triplet=x64-mingw-static
+
+# build proj statically for windows x64
+WORKDIR ${PROJECT_FOLDER}/${PROJ_VERSION}/build
+RUN cmake -DCMAKE_TOOLCHAIN_FILE=/vcpkg/scripts/buildsystems/vcpkg.cmake \
+          -DCMAKE_SYSTEM_NAME=Windows \
+          -DVCPKG_TARGET_TRIPLET=x64-mingw-static \
+          -DCMAKE_C_COMPILER=x86_64-w64-mingw32-gcc \
+          -DCMAKE_CXX_COMPILER=x86_64-w64-mingw32-g++ \
+          -DCMAKE_INSTALL_PREFIX=/usr/local/ \
+          -DCMAKE_BUILD_TYPE=Release \
+          -DBUILD_APPS=OFF \
+          -DBUILD_SHARED_LIBS=OFF \
+          -DENABLE_CURL=OFF \
+          -DENABLE_TIFF=ON \
+          -DBUILD_TESTING=OFF .. \
+          -DEMBED_PROJ_DATA_PATH=OFF \ 
+          .. 
+RUN cmake --build . --config Release -j $(nproc)
+RUN cmake --build . --target install -j $(nproc)
+
+# BUILD_ID will force cache invalidation at every build if docker build is run with eg --build-arg BUILD_ID=$(date +%s) 
+RUN echo "build id: $BUILD_ID"
+
+# clone the source and prepare the build dir
+WORKDIR ${PROJECT_FOLDER}/build
+COPY . .
+RUN mkdir -p ./bin
+
+# build the go app for windows x64 statically using cgo
+RUN PKG_CONFIG_PATH="/vcpkg/installed/x64-mingw-static/lib/pkgconfig" \
+    CC=x86_64-w64-mingw32-gcc \
+    CGO_ENABLED=1 \
+    CGO_LDFLAGS='-L/vcpkg/installed/x64-mingw-static/lib -g -O2 -static -lstdc++ -lsqlite3 -ltiff -lzlib -ljpeg -llzma -lm' \
+    GOOS="windows" \
+    GOARCH="amd64" \
+    go build -o ./bin/gocesiumtiler.exe -ldflags "-X main.GitCommit=$(git rev-list -1 HEAD)" ./cmd/main.go
+
+
+##################################
+#           Packaging            #
+##################################
+FROM scratch AS final
+ARG PROJECT_FOLDER="/usr/src/gocesiumtiler"
+COPY --from=linux-builder /usr/local/share/proj /share
+COPY --from=linux-builder ${PROJECT_FOLDER}/build/bin/gocesiumtiler /gocesiumtiler-lin-x64
+COPY --from=windows-builder ${PROJECT_FOLDER}/build/bin/gocesiumtiler.exe /gocesiumtiler-win-x64.exe

LICENSE-3RD-PARTIES.md

@@ -35,14 +35,6 @@ furnished to do so, subject to the following conditions:
 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.
 
-
-##### Sean Barbeau [earth-gravitational-model](https://github.com/barbeau/earth-gravitational-model)
-*a Java port of the geotools EarthGravitationalModel code*
-(Go Cesium Tiler library carries a complete golang porting of the aforementioned Java library by Sean Barbeau)
-> N.B. This library does not explicitely state a licensing scheme, but as it is a porting of the GeoTools EarthGravitationalModel
-it is assumed that it uses the same LGPL license
-
-
 ##### TUM-GIS [cesium-point-cloud-generator](https://github.com/tum-gis/cesium-point-cloud-generator)
 *A small Java-based tool for the generation of point cloud visualization datasets according to Cesium 3D Tiles.*
 > This library has been the main source of inspiration in writing the Go Cesium Tiler library, in particular for