Update C++ docs for auto-downloaded arrow (#4064)

### What

* Part of  #3962

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested [demo.rerun.io](https://demo.rerun.io/pr/4064) (if
applicable)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG

- [PR Build Summary](https://build.rerun.io/pr/4064)
- [Docs
preview](https://rerun.io/preview/ae3c74d303c64121864d9982c455b5cbd5dfb2ad/docs)
<!--DOCS-PREVIEW-->
- [Examples
preview](https://rerun.io/preview/ae3c74d303c64121864d9982c455b5cbd5dfb2ad/examples)
<!--EXAMPLES-PREVIEW-->
- [Recent benchmark results](https://ref.rerun.io/dev/bench/)
- [Wasm size tracking](https://ref.rerun.io/dev/sizes/)

.vscode/settings.json

@@ -8,6 +8,10 @@
     "files.insertFinalNewline": true,
     "files.trimTrailingWhitespace": true,
     "files.autoGuessEncoding": true,
+    "cSpell.ignorePaths": [
+        ".vscode",
+        "pixi.lock"
+    ],
     "cSpell.words": [
         "andreas",
         "bbox",

crates/re_viewer/data/quick_start_guides/cpp_connect.md

@@ -15,21 +15,18 @@ Using `pip`:
 After you have installed it, type `rerun` in your terminal to start the viewer.
 
 
-#### Using the Rerun C++ SDK
-First you need to install the `arrow-cpp` library on your system using your favorite package manager.
-If you are using [Pixi](https://prefix.dev/docs/pixi/overview), you can simply type `pixi global install arrow-cpp`.
-Find more information at the official Arrow Apache [install guide](https://arrow.apache.org/install/).
-
-If you're using CMake, you can add the following to your `CMakeLists.txt`:
-
+#### Using the Rerun C++ SDK with CMake
 ```cmake
 include(FetchContent)
 FetchContent_Declare(rerun_sdk URL
     https://github.com/rerun-io/rerun/releases/latest/download/rerun_cpp_sdk.zip)
 FetchContent_MakeAvailable(rerun_sdk)
 ```
 
-This will download a bundle with pre-built Rerun C static libraries for most desktop platforms, all Rerun C++ sources and headers, as well as CMake build instructions for them.
+This will download a bundle with pre-built Rerun C static libraries for most desktop platforms,
+all Rerun C++ sources and headers, as well as CMake build instructions for them.
+By default this will in turn download & build [Apache Arrow](https://arrow.apache.org/)'s C++ library which is required to build the Rerun C++.
+See [Install arrow-cpp](https://www.rerun.io/docs/howto/arrow-cpp-install?speculative-link) to learn more about this step and how to use an existing install.
 
 Make sure you link with `rerun_sdk`:
 ```cmake

docs/content/getting-started/cpp.md

@@ -6,24 +6,14 @@ order: 2
 ## Setup
 Before adding Rerun to your application, start by [installing the viewer](installing-viewer.md).
 
-The Rerun C++ SDK depends on an install of the `arrow-cpp` library on your system using.
-
-🚧 In the future we want to make this part of the setup easier.
-
-### Installing arrow-cpp with pixi
-See our [how-to guide](../howto/arrow-cpp-pixi.md) on using pixi to install `arrow-cpp`.
-
-### Installing arrow-cpp manually
-Find more information about other package managers at the official Arrow Apache [install guide](https://arrow.apache.org/install/).
-
 ## Learning by example
 If you prefer to learn by example, check out our example repository which uses the Rerun C++ SDK to log some data from Eigen and OpenCV: <https://github.com/rerun-io/cpp-example-opencv-eigen>.
 
 ## Using Rerun with CMake
 
 Assuming you are starting with a bare-bones `CMakeLists.txt` such as:
 ```cmake
-cmake_minimum_required(VERSION 3.16)
+cmake_minimum_required(VERSION 3.16...3.27)
 project(example_minimal LANGUAGES CXX)
 
 add_executable(example_minimal main.cpp)
@@ -36,7 +26,10 @@ FetchContent_Declare(rerun_sdk URL
     https://github.com/rerun-io/rerun/releases/latest/download/rerun_cpp_sdk.zip)
 FetchContent_MakeAvailable(rerun_sdk)
 ```
-This will download a bundle with pre-built Rerun C static libraries for most desktop platforms, all Rerun C++ sources and headers, as well as CMake build instructions for them.
+This will download a bundle with pre-built Rerun C static libraries for most desktop platforms,
+all Rerun C++ sources and headers, as well as CMake build instructions for them.
+By default this will in turn download & build [Apache Arrow](https://arrow.apache.org/)'s C++ library which is required to build the Rerun C++.
+See [Install arrow-cpp](../howto/arrow-cpp-install.md) to learn more about this step and how to use an existing install.
 
 Currently, Rerun SDK works with C++17 or newer, so you need to add this property to your target:
 ```cmake

docs/content/howto/arrow-cpp-pixi.md → docs/content/howto/arrow-cpp-install.md

@@ -1,11 +1,30 @@
 ---
-title: Install arrow-cpp with pixi
+title: Install arrow-cpp
 order: 6
 ---
+
+# Automatically download & build arrow from source (default)
+
+By default, the Rerun C++ SDK's CMake script (which is part of the SDK's zip artifact that can be fetched via `FetchContent`)
+will download a known compatible version of Arrow from GitHub and add it to the build.
+The build configuration is kept to the minimum required by the Rerun C++ SDK.
+
+To instead use an existing install of Arrow, disable the CMake build option `RERUN_DOWNLOAD_AND_BUILD_ARROW`.
+(by passing `-DRERUN_DOWNLOAD_AND_BUILD_ARROW=OFF` to your CMake configure step).
+This will cause Rerun to instead use CMake's `find_package` to look for a ready-to-use install of the Arrow C++ library.
+
+# Install arrow-cpp with Pixi
+
 [Pixi](https://prefix.dev/docs/pixi/overview) is a convenient tool for managing cross-platform project dependencies. In
 fact, Rerun uses it for our own internal development dependency management, and you will find `pixi.toml` files in most
 of our external examples.
 
+Make sure to use `-DRERUN_DOWNLOAD_AND_BUILD_ARROW=OFF` when building, otherwise Rerun's CMake script
+will download & build arrow instead, ignoring your Pixi install.
+The advantage of using Pixi is that you can rely on pre-built artifacts rather than adding Arrows build to your own.
+Also, Pixi is of course also useful for managing other dependencies like Eigen or OpenCV,
+as well as fr pinning the version of your build tooling.
+
 ## Installing Pixi
 On Mac or Linux you can just run:
 ```
@@ -61,4 +80,6 @@ pixi run example
 ⚠️ [#4050](https://github.com/rerun-io/rerun/issues/4050) `arrow-cpp` needs to be held back to 10.0.1 to avoid conflicts
 with the `rerun-sdk` package when installed in the same pixi environment.
 
-⚠️ On Windows pixi only downloads release binaries which are **not** compatible with debug builds, causing runtime crashes. For debug builds you have to build Arrow yourself, see [Building Arrow C++](https://arrow.apache.org/docs/developers/cpp/building.html).
+⚠️ On Windows pixi only downloads release binaries which are **not** compatible with debug builds, causing runtime crashes.
+For debug builds you have to build Arrow yourself, see [Building Arrow C++](https://arrow.apache.org/docs/developers/cpp/building.html)
+or stick with `RERUN_DOWNLOAD_AND_BUILD_ARROW=ON`.

docs/cspell.json

@@ -85,6 +85,7 @@
     "downscaled",
     "downscaling",
     "drawables",
+    "DRERUN",
     "dtype",
     "dtypes",
     "eframe",

rerun_cpp/CMakeLists.txt

@@ -163,6 +163,7 @@ if(RERUN_DOWNLOAD_AND_BUILD_ARROW)
         GIT_REPOSITORY https://github.com/apache/arrow.git
         GIT_TAG apache-arrow-10.0.1
         GIT_SHALLOW true
+        GIT_PROGRESS true
         CMAKE_ARGS
         --preset ninja-debug-minimal
         -DARROW_IPC=ON