Add C++ version

Minimal source changes. No-content run produces help output.

Compiles, but not level-4 warning clean on MSVC.

ray4/.gitignore

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+# Git Ignore -- ray4
+
+/build/

ray4/CHANGELOG.md

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+Change Log -- `ray4`
+====================================================================================================
+
+# 1.0.0-alpha.1 (in progress)
+  - First conversion from the original C to C++.
+

ray4/CMakeLists.txt

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+#---------------------------------------------------------------------------------------------------
+# CMake Build Configuration for the ray4 4D raytracer
+#---------------------------------------------------------------------------------------------------
+
+cmake_minimum_required(VERSION 3.10.0...3.30.5)
+
+set (CMAKE_CXX_STANDARD          17)
+set (CMAKE_CXX_STANDARD_REQUIRED ON)
+set (CMAKE_CXX_EXTENSIONS        OFF)
+
+project (ray4 LANGUAGES CXX)
+
+# Source
+set ( sources_ray4
+  src/r4_globals.h
+  src/r4_hit.cpp
+  src/r4_image.h
+  src/r4_io.cpp
+  src/r4_main.cpp
+  src/r4_parse.cpp
+  src/r4_trace.cpp
+  src/r4_vec.cpp
+  src/ray4.h
+  src/vector.h
+)
+
+add_executable (ray4 ${sources_ray4})

ray4/README.md

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+ray4
+====================================================================================================
+
+This is `ray4`, a 4D raytracer I wrote for my master’s thesis in May 1991
+([_Four-Space Visualization of 4D Objects_][thesis]).
+
+Ray4 User Manual
+-----------------
+See the [Ray4 User Manual][] for usage information.
+
+
+Project Structure
+------------------
+This project includes the following directories:
+
+  | Directory   |                                             |
+  |-------------|---------------------------------------------|
+  | [craig/][]  | Mark Craig contributions                    |
+  | distribute/ | Old (now unused) files for FTP distribution |
+  | inputs.r4/  | Sample input ray4 files                     |
+  | src/        | ray4 source code                            |
+
+
+Building
+---------
+This project now builds with CMake, which should allow the code to work on all CMake-supported
+platforms. Build from the `/ray4/ray4/` directory.
+
+
+Example Run
+-----------
+
+    ray4 -b12 -idots.r4 -odots.icube -a10:11:20 -r78:65:12
+    r4toiff dots.icube -t
+
+
+Beta Testers
+------------
+Thanks to the following beta testers for helping me with this code:
+
+  - Greg Aharonian
+  - Brian Carney
+  - Mark Craig
+  - Mark Ferneau
+  - Marty Ryan
+
+----
+Steve Hollasch / [email protected]
+
+
+
+[craig/]:           craig/README.md
+[Ray4 User Manual]: ray4.md
+[thesis]:           https://hollasch.github.io/ray4/Four-Space_Visualization_of_4D_Objects.html

ray4/craig/README.md

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+Mark Craig Contributions
+====================================================================================================
+
+NOTE: To convert ray4 image files to SUN rasterfile, you need the PBM graphics package - See below
+for info.
+
+`run` and `run2` are sample scripts that can be used to run ray4 in the background. For example
+`run dots` will raytrace the dots.r4 input file in the background redirecting all screen output to
+the file `temp` and saving the ray4 image file as `dots.icube`.
+
+To convert ray4 image data files to MTV format, use `r4tomtv`. r4tomtv uses the same command line
+arguments as r4tosgi. It will create MTV files whose name is of the form:
+
+    slice_(data file prefix)_(zplane)
+
+For example: `slice_dots_0` would be the 0 zplane slice of the `dots.icube` file.
+
+To convert an individual MTV file to SUN rasterfile, use `mtvtorast`. For example: `mtvtorast
+slice_dots_0` will create the SUN rasterfile named `slice_dots_0.ras`. `screenload slice_dots_0.ras`
+will display the image on a SUN.
+
+`convert` will convert all slice MTV files to SUN rasterfile automatically. It also will delete all
+MTV slice files if the user responds with "y" to the delete files prompt.
+
+To display an individual MTV file on a SUN screen without saving to a SUN rasterfile, use `display`.
+For example: `display slice_dots_0` will convert and display the slice.
+
+Additional information (I don't know if the email addresses are still valid):
+
+**MTV** --
+  MTV RAYTRACER written by Mark Terrence VandeWettering ([email protected])
+
+**PBM** --
+  Extended Portable Bitmap Toolkit written by Jef Poskanzer ([email protected])
+  `{ucbvax, lll-crg, sun!pacbell, apple, hplabs}!well!pokey`
+
+Both available at many anonymous FTP sites.
+
+Mark R. Craig
+<br>Florida Institute of Technology
+<br>[email protected]

ray4/craig/convert

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+#!/bin/sh
+files=`ls slice_*`
+for i in $files
+do
+	echo
+	echo $i:
+	mtvtorast $i
+done
+echo "Delete data files: (y/n): "
+read del
+if test "$del" = y
+then
+	for i in $files
+	do
+		rm -i $i
+	done
+fi