# 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](https://rubygems.org/gems/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](#Example) down below).

## Installation

Add this line to your application's Gemfile:

```ruby
gem 'stb_image_ffi'
```

And then execute:

    $ bundle

Or install it yourself as:

    $ gem install stb_image_ffi

## Example

```ruby
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](https://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](http://contributor-covenant.org) code of conduct.

## License

The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).

## 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](https://github.com/boatrite/stb_image_ffi/blob/master/CODE_OF_CONDUCT.md).