STBImage

Very naive bindings for stb_image.h. Implements only stbi_set_flip_vertically_on_load and stb_load since these are the 2 functions I need to load an image as a texture in OpenGL.

The reason I made this instead of using stb-image is because stb-image didn't implement stbi_set_flip_vertically_on_load, as far as I can tell, which is useful/necessary when wanting to load image data in a format immediately consumable by OpenGL (see Example down below).

Installation

Add this line to your application's Gemfile:

gem 'stb_image_ffi'

And then execute:

$ bundle

Or install it yourself as:

$ gem install stb_image_ffi

Example

STBImage.stbi_set_flip_vertically_on_load 1

file = "image.jpg"
width_ptr = " " * 8
height_ptr = " " * 8
channels_ptr = " " * 8
desired_channels = 3
ptr = STBImage.stbi_load(file, width_ptr, height_ptr, channels_ptr, desired_channels)
width = width_ptr.unpack1 "L"
height = height_ptr.unpack1 "L"
channels = channels_ptr.unpack1 "L"
data = ptr.get_bytes(0, width * height * channels)
# ...
glTexStorage2D(GL_TEXTURE_2D, 1, GL_RGB8, width, height)
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_RGB, GL_UNSIGNED_BYTE, data)

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/boatrite/stb_image_ffi. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the STBImage project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.