v3.1.0 (2020-05-03)

This minor upgrade adds some fixes and changes that are a bit more than just patches. The text now
has subchapter headings to help readers browse content and get a bit more context. We're introducing
new type aliases point3 and color for vec3 to better indicate the underlying mathematical
types of parameters and variables. Overall, a bunch of small improvements that we'd recommend
adopting, but may warrant comparison with any current projects.

Common

• Fix: Include cmath in vec3.h (#501)
• Fix: Scattered improvements to the text
• New: Subchapters throughout all three books (#267)
• New: Add explanation for padding aarect in the zero dimension (#488)
• Change: Minor change to use new point3 and color type aliases for vec3 (#422)
• Change: Renamed constant_texture to solid_color, add RGB constructor (#452)
• Change: Moved vec3::write_color() method to utility function in color.h header (#502)
• Change: Switch from ffmin/ffmax to standard fmin/fmax (#444, #491)
• Change: Math notation to bold uppercase points, bold lowercase no-barb vectors (#412)
• Change: Books use Markdeep's image class=pixel for rendered image fidelity (#498)

In One Weekend

• Fix: Improve image size and aspect ratio calculation to make size changes easier
• Fix: Added t parameter back into hit_record at correct place
• Fix: image basic vectors off by one
• Fix: Update image and size for first PPM image
• Fix: Update image and size for blue-to-white gradient image
• Fix: Update image and size for simple red sphere render
• Fix: Update image and size for sphere with normal-vector coloring
• Fix: Correct typo in "What's next?" list to rejoin split paragraph on "Lights." Adjust numbering
  in rest of list.
• Change: Define image aspect ratio up front, then image height from that and the image width
• Change: Default image sizes changed from 200x100 to 384x216
• Change: First image size changed to 256x256

The Next Week

• Change: Large rewrite of the image_texture class. Now handles image loading too. (#434)

v3.0.2 (2020-04-11)

Common

• Fix: code styling for source code both inline and in fenced blocks (#430)
• Change: Every book source now includes from a single common acknowledgments document

In One Weekend

• Fix: Correct typo: "consine" to "cosine"

The Next Week

• Fix: shared_ptr dereference and simplify code in hittable_list::bounding_box() (#435)
• Fix: Erroneous en-dash in code block. Replace –> with -> (#439)
• Fix: Introduce u,v surface coordinates to hit_record (#441)
• Fix: Add highlight to new hittable::bounding_box() method (#442)

The Rest of Your Life

• Fix: unitialized variable in first version of integrate_x_sq.cc
• Fix: remove unreferenced variables in several sample programs
• Fix: correct program computation of the integral of x^2 (#438)

v3.0.1 (2020-03-31)

Common

• Fix: Display rendered images as pixelated instead of smoothed (#179)
• Deleted: delete old README files specific to each book (#410)

In One Weekend

• Fix: Remove duplicated text and reword on the camera up vector (#420)

v3.0.0 (2020-03-23)

With the migration to a web format accomplished in v2.0.0, we immediately began work on a new major
release: v3.0.0. This release tackles the following key themes:

• Establishing a common build system for the three projects. We chose CMake for its broad support
  for multiple platforms, as well as multiple build tools and IDEs. This change includes a
  reorganization of the project source files, and unifying a lot of code across projects.

• A major upgrade of the project source code, addressing a number of large changes that we had
  deferred for later.

• A number of larger changes to the book content, refining some approaches and ideas, and
  addressing some areas in the text that needed improvement.

Following this release, we expect to switch to a much more incremental approach, mostly with
patch-level (fix) changes and some minor-level (addition) changes.

Common to All Project Source

• Change: Default floating-point type changed from float to double (#150)
• Change: Materials are now referenced with std::shared_ptr pointers
• Change: Complete elimination of bare pointers and new/delete
• Change: hittable_list uses std::vector plus std::shared_ptr pointers
• Change: Header cleanup across the source code (#218, #220)
• Change: Cleaned up standard C++ header use (#19)
• Change: Improved random number generator utilities
• Change: Replace MAXFLOAT with (portable) infinity (#195, #216)
• Change: A lot of code cleanup, refactoring, renaming (#192)
• Change: Disable compile warnings for external stb_image.h on Windows
• Change: Replace pi with portable version (#207)
• Change: ray_color() function now has max depth passed in, rather than hard-coding it (#143)
• Change: Added random_in_unit_sphere(), random_unit_vector(), random_in_hemisphere() to
  vec3.h. Fixed places where we were using one but should have been using another. (#145)
• Change: General rework of the vec3 header (#153, #156, #215)
• Change: Clarify sphere intersection code, plus slight perf improvement (#113)
• Change: ray::point_at_parameter() renamed to ray::at()
• Change: Moved ffmin(), ffmax() from aabb.h to rtweekend.h
• Change: Move low-level utility functions to more appropriate headers
• Change: squared_length() renamed to length_squared()
• Change: Update sphere::hit() function.
• Change: Refraction variables renamed to match reflection variable names
• Change: Simplify lambertian scatter direction calculation
• New: CMake configuration & build
• New: Added progress output for main programs (#139)
• New: src/common directory for code shared across books
• New: Common project-wide header: src/common/rtweekend.h
• New: File constants.h with portable math constants (#151)
• New: vec3::write_color - provides a robust output method for color data (#93)
• New: degrees_to_radians() utility function (#217)
• New: random_int(), random_double(), and vec3::random() utility functions
• New: Added safety value when surface texture has null data
• New: Main programs now define and handle parameterized background color
• Fix: Diffuse PDF computation uses random point on sphere, rather than inside
• Fix: Improve color [0,1] -> [0,255] mapping

Common to All Books

• Change: Code in source and in book reformatted to a consistent 96-column line length (#219)
• Change: Lots more highlighting of changed code in books to aid reading
• Change: Math typesetting fixes throughout the books (#13)
• Change: Books now use Markdeep's chapter indirection syntax
• Change: Updated several output images to match code updates
• Change: Books general styling improvements (#197)
• Change: Refactored acknowledgements. These are now moved to and duplicated in each book
• New: Added code listing captions, including source file name, for all books (#238)
• New: Added captions to all figures (#238)
• New: Local copy of markdeep.min.js for offline reading
• Fix: Fixed various minor problems in the text

In One Weekend

• Change: Reworked Lambertian reflection text (#155)
• Change: Revised the figure for computing a random reflection vector (#142)
• New: Clarified text around the ideal Lambertian distribution (#155)
• New: Additional explanatory text to the dielectric chapter
• New: Image for hemispherical rendering
• New: Image for dealing with front and back faces (#326)
• Fix: Update ray_color() code blocks to match current source (#391)

The Next Week

• Change: Added proper handling of front vs back face intersection (#270)
• New: "The Next Week" main program added swtich statement for different scenes
• New: "The Next Week" main program now defines all image/camera parameters for each scene
• Fix: Fixed bug in noise_texture::value() (#396)
• Fix: Correct first Perlin noise() function in "The Next Week".
• Fix: Fix OCR error in texture::value() function (#399)
• Fix: Remove premature declaration of moving_sphere::bounding_box() (#405)

The Rest of Your Life

• Change: Improved naming of auxilliary programs in The Rest of Your Life source
• Fix: Delete unused variable p in main() (#317)
• Deleted: Several unused source files from src/TheRestOfYourLife

v2.0.0 (2019-10-07)

This major release marks an overhaul of the entire series, moving from a primarily PDF format to a
web accessible format using Markdeep (https://casual-effects.com/markdeep/). This represents a huge
overhaul to the contents, particularly around source code blocks in the text, mathematical
typesetting and source-code cleanup.

Common

• Change: Moved existing InOneWeekend, TheNextWeek, TheRestOfYourLife content to io repo
• Change: Rewrote vec3.h cross function for clarity
• New: General release to web
• New: Created single monolithic raytracing.github.io repo
• New: License change to CC0 in COPYING.txt
• New: CHANGELOG.md
• New: CONTRIBUTING.md
• New: COPYING.txt
• New: README.md
• New: raytracing.github.io links to all the three books
• New: CSS for all books
• New: CSS for the print variant of the books
• Fix: All instances of hitable have become hittable
• Fix: Replaced drand48() with portable random_double number generation
• Delete: Deprecated existing InOneWeekend, TheNextWeek, TheRestOfYourLife repos

In One Weekend

• Change: README files updated for top level, source, and books
• Change: Text, Chapter 0 Overview has become Chapter 1, all subsequent chapters incremented
• Change: Text, Syntax highlighting of source modifications
• Change: Text, Chapter 3, Reorder include files in code blocks to match src conventions
• Change: Text, Chapter 3, Consistent use of spaces in code blocks
• Change: Text, Chapter 3, Reordered vec3 class functions to + - * /
• Change: Text, Chapter 4, Reorder include files in code blocks to match src conventions
• Change: Text, Chapter 6, Reorder include files in code blocks to match src conventions
• Change: Text, Chapter 6, Consistent use of spaces in code blocks
• Change: Text, Chapter 7, Consistent use of spaces in code blocks
• Change: Text, Chapter 9, Consistent use of spaces in code blocks
• Change: Text, Chapter 9, Put function signatures and { on the same line
• Change: Text, Chapter 10, Consistent use of spaces in code blocks
• Change: Text, Chapter 10, Put function signatures and { on the same line
• Change: Text, Chapter 11, Consistent use of spaces in code blocks
• Change: Text, Chapter 13, Put function signatures and { on the same line
• New: Markdeep page created for entire body of text
• New: Markdeep MathJax for formulae and equations for body of text
• New: raytracing.github.io/books/RayTracingInOneWeekend.html
• Fix: Text, Chapter 7, Add #include "random.h" in code blocks
• Fix: Text, Chapter 10, Added metal fuzziness parameter for initial dielectric
• Fix: Text, Chapter 13, Added metal fuzziness parameter
• Fix: Code, Removed extraneous ; from vec3::&operator[] signature
• Delete: Code, vec3 p = r.point_at_parameter(2.0); in main.cc

The Next Week

• Change: Text, Chapter 0 Overview has become Chapter 1, all subsequent chapters incremented
• Change: Text, Syntax highlighting of source modifications
• Change: Text, Chapter 2, Consistent use of spaces in code blocks
• Change: Text, Chapter 3, Consistent use of spaces in code blocks
• Change: Text, Chapter 4, Consistent use of spaces in code blocks
• Change: Text, Chapter 5, Consistent use of spaces in code blocks
• Change: Text, Chapter 5, added "texture" to "We can use that texture on some spheres"
• Change: Text, Chapter 7, Consistent use of spaces in code blocks
• Change: Text, Chapter 7, "This is yz and xz" changed to "This is xz and yz"
• Change: Text, Chapter 8, Changed "And the changes to Cornell is" to "... Cornell are"
• Change: Text, Chapter 9, Changed short if statements to two lines for Consistency
• Change: Text, Chapter 10, Consistent use of spaces in code blocks
• Change: Code and Text, Chapter 9, cleaned up implementation of constant_medium::hit
• Change: Code and Text, Chapter 9, Rewrote debug functionality in constant_medium::hit
• New: raytracing.github.io/books/RayTracingTheNextWeek.html
• New: README.md, source README.md
• New: Markdeep page created for entire body of text
• New: Markdeep MathJax created for formulae and equations for body of text
• New: Earth map picture for use in rendering
• Fix: Text, Chapter 2, The lambertian class definition now uses vec3 instead of texture
• Fix: Text, Chapter 7, Changed cornell_box hittable array size to 5
• Fix: Code and Text, Chapter 3, Changed List[0] to List[i] in hittable_list::bounding_box()
• Fix: Code and Text, Chapter 3, Replaced fmax and fmin with ffmax and ffmin
• Fix: Code, Add missing headers to constant_medium.h to fix g++ compiler error

The Rest of Your Life

• Change: Text, Chapter 0 Overview has become Chapter 1, all subsequent chapters incremented
• Change: Text, Syntax highlighting of source modifications
• Change: Text, Chapter 2, Reorder include files in code blocks to match src conventions
• Change: Text, Chapter 3, Reorder include files in code blocks to match src conventions
• Change: Text, Chapter 6, Consistent use of spaces in code blocks
• Change: Text, Chapter 6, Consistent use of spaces in code blocks
• Change: Text, Chapter 8, Changed calculation of a axis to pseudocode
• Change: Text, Chapter 8, Consistent use of spaces in code blocks
• New: raytracing.github.io/books/RayTracingTheRestOfYourLife.html
• New: README.md, source README.md
• New: Markdeep page created for entire body of text
• New: Markdeep MathJax created for formulae and equations for body of text
• Fix: Text, Chapter order starting from chapter 2
• Fix: Text, Renamed figures and images to match new chapter numbering
• Fix: Text, Chapter 4, Rewrote formula for "Color" to "Color = A * color(direction"
• Fix: Code and Text, Chapter 6, material::scattering_pdf now returns type float
• Fix: Code and Text, Chapter 6, removal of factor of 2 to random_cosine_direction calculation

Ray Tracing: The Rest Of Your Life v1.123.0

• The Ray Tracing in One Weekend book series is now free!
• First GitHub release of Ray Tracing: The Rest Of Your Life, bundled with source code.

Ray Tracing In One Weekend v1.54.0

• The Ray Tracing in One Weekend book series is now free!
• First GitHub release of Ray Tracing In One Weekend, bundled with source code.

Ray Tracing: The Next Week v1.42.0

• The Ray Tracing In One Weekend book series is now free!
• First GitHub release of Ray Tracing: The Next Week, bundled with source code.