Add Opengl documentation (gl4 + gl2.1)

Author: Suraj-Yadav

docs/file-scrapers.md

@@ -161,6 +161,19 @@ curl https://v2.ocaml.org/releases/$VERSION/ocaml-$VERSION-refman-html.tar.gz |
 tar xz --transform 's/htmlman/ocaml/' --directory docs/
 ```
 
+## Opengl
+
+Clone https://github.com/KhronosGroup/OpenGL-Refpages.git
+
+```sh
+DEVDOCS_ROOT=/path/to/devdocs
+git clone https://github.com/KhronosGroup/OpenGL-Refpages.git
+mkdir $DEVDOCS_ROOT/docs/opengl~gl4
+mkdir $DEVDOCS_ROOT/docs/opengl~gl2.1
+cp -r OpenGL-Refpages/gl4/html/* "$DEVDOCS_ROOT/docs/opengl~gl4"
+cp -r OpenGL-Refpages/gl2.1/xhtml/* "$DEVDOCS_ROOT/docs/opengl~gl2.1"
+```
+
 ## OpenJDK
 Search 'Openjdk' in https://www.debian.org/distrib/packages, find the `openjdk-$VERSION-doc` package,
 download it, extract it with `dpkg -x $PACKAGE ./` and move `./usr/share/doc/openjdk-16-jre-headless/api/`

lib/docs/filters/opengl/clean_html.rb

@@ -0,0 +1,22 @@
+module Docs
+    class Opengl
+      class CleanHtmlFilter < Filter
+        def call
+          # Rmeove table from function definitions
+          css('.funcprototype-table').each do |node|
+            node.css('td').each do |data|
+              data.replace(data.children)
+            end
+            node.css('tr').each do |row|
+              row.replace(row.children)
+            end
+            node.wrap('<div>')
+            node.parent['id'] = node.css('.fsfunc').text
+            node.replace(node.children)
+          end
+
+          doc
+        end
+      end
+    end
+  end

lib/docs/filters/opengl/entries.rb

@@ -0,0 +1,24 @@
+module Docs
+  class Opengl
+    class EntriesFilter < Docs::EntriesFilter
+      def get_name
+        slug.chomp('.xhtml').chomp('.xml')
+      end
+
+      # gl4 also has documentation of GLSL, this string is present under Version Support
+      def get_type
+        return 'GLSL' if html.include?('OpenGL Shading Language Version')
+        'OpenGL'
+      end
+
+      # functions like glUniform1f, glUniform2f, glUniform... have the same documentation
+      def additional_entries
+        entries = []
+        css('.fsfunc').each do |function|
+          entries << [ function.text, function.text ]
+        end
+        entries
+      end
+    end
+  end
+end

lib/docs/scrapers/opengl.rb

@@ -0,0 +1,34 @@
+module Docs
+  class Opengl < FileScraper
+    self.type = 'simple'
+    self.root_path = 'index.php'
+    self.links = {
+      home: 'https://registry.khronos.org/OpenGL-Refpages/'
+    }
+    html_filters.push 'opengl/entries', 'opengl/clean_html'
+
+    # indexflat.php is a copy of index.php
+    options[:skip] = %w(indexflat.php)
+
+    options[:attribution] = <<-HTML
+    Copyright 2017-2021 The Khronos Group, Inc.. This work is licensed
+    under a <a href="http://creativecommons.org/licenses/by/4.0/">Creative
+    Commons Attribution 4.0 International License</a>.
+    HTML
+
+    version 'gl2.1' do
+      self.root_path = 'index.html'
+      self.release = 'gl2.1'
+      self.base_url = "https://registry.khronos.org/OpenGL-Refpages/#{self.version}/"
+    end
+    version 'gl4' do
+      self.root_path = 'index.php'
+      self.release = 'gl4'
+      self.base_url = "https://registry.khronos.org/OpenGL-Refpages/#{self.version}/"
+    end
+
+    def get_latest_version(opts)
+      return 'v1.0.0'
+    end
+  end
+end

public/icons/docs/opengl/16.png

@@ -0,0 +1 @@
+https://www.khronos.org/legal/trademarks/