Staticmethod

#!/usr/bin/env ruby -rubygems
# Name:  nehe_lesson02.rb
# Purpose: An implementation of NeHe's OpenGL Lesson #02
#          using ruby-opengl (http://nehe.gamedev.net/)
# 

#  some bug fixed by Ranska  
#

require "sdl"
require "opengl"
require "mathn"
require "find"

# Add GL and GLUT namespaces in to make porting easier
#include Gl
#include Glu        I have comment this because that didn't on my linux/mandriva
#include Glut

# Placeholder for the window object
window = ""

@objectsToDraw = Array.new

class PictureCollection
    attr_accessor :current_picture

    def initialize
        @pictures = Array.new
        @current_picture = -1
    end

    def select_next_picture
        @current_picture += 1 if (@current_picture + 1) != @pictures.size
    end

    def select_previous_picture
        @current_picture -= 1 if (@current_picture - 1) >= 0
    end

    def num_prepictures
        if @current_picture > -1
            @current_picture
        else
            0
        end
    end

    def num_postpictures
        @pictures.size - @current_picture - 1
    end

    def get_picture(pos)
        @pictures[pos] if pos > -1
    end

    def add_picture(pic)
        @pictures.push pic
        @current_picture = 0 if(@current_picture == -1)
    end

    def each
        @pictures.each do |pic|
            yield pic
        end
    end

    def length
        @pictures.length
    end
end

class Picture 
  def initialize(filename, number)
    surface = SDL::Surface.load(filename)
    texture = GL::GenTextures(1)
    GL::BindTexture(GL::TEXTURE_2D, texture[0])
    GL::TexImage2D(GL::TEXTURE_2D, 0, 3, surface.w, surface.h, 0, GL::RGB, GL::UNSIGNED_BYTE, surface.pixels)
    GL::TexParameteri(GL::TEXTURE_2D, GL::TEXTURE_MIN_FILTER, GL::LINEAR)
    GL::TexParameteri(GL::TEXTURE_2D, GL::TEXTURE_MAG_FILTER, GL::LINEAR)
    surface = nil #hopefully this gets garbage collected
    @textureId = texture[0] # Store the Texture ID
  end

def draw
    GL::BindTexture(GL::TEXTURE_2D, @textureId)
    GL::MatrixMode(GL::TEXTURE)
    GL::LoadIdentity()
    GL::Rotate(180,0,0,1)
    GL::Scale(-1,1,1)
    GL::MatrixMode(GL::MODELVIEW)
    # Draw a rectangle
    GL::Begin(GL::QUADS)
      GL::TexCoord(0,0)
      GL::Vertex(-1.0, -1.0, 0.0) # Bottom Left
      GL::TexCoord(1,0)
      GL::Vertex( 1.0, -1.0, 0.0) # Bottom Right
      GL::TexCoord(1,1)
      GL::Vertex( 1.0,  1.0, 0.0) # Top Right
      GL::TexCoord(0,1)
      GL::Vertex(-1.0,  1.0, 0.0) # Top Left
    GL::End()
  end
end

def init_gl_window(width = 640, height = 480)
        GL::Viewport(0,0, width, height)
    # Background color to black
    GL::ClearColor(0.0, 0.0, 0.0, 0)
    # Enables clearing of depth buffer
    GL::ClearDepth(1.0)
    # Set type of depth test
    GL::DepthFunc(GL::LEQUAL)
    # Enable Textures
   GL::Enable(GL::TEXTURE_2D)
    # Enable depth testing
    GL::Enable(GL::DEPTH_TEST)
    # Enable smooth color shading
    GL::ShadeModel(GL::SMOOTH)
    GL::MatrixMode(GL::PROJECTION)
    GL::LoadIdentity()
    # Calculate aspect ratio of the window
    GLU::Perspective(60.0, width / height, 0.1, 100.0)
    GL::MatrixMode(GL::MODELVIEW)

end

#draw_gl_scene = Proc.new do
def draw_gl_scene
    # Clear the screen and depth buffer
    GL::Clear(GL::COLOR_BUFFER_BIT | GL::DEPTH_BUFFER_BIT)
    # Reset the view
    GL::MatrixMode(GL::MODELVIEW);
    GL::LoadIdentity();
        # Draw main picture
        GL::Translate(0,0,-4)
        @objectsToDraw.get_picture(@objectsToDraw.current_picture).draw ;
        GL::LoadIdentity();
        # Draw pre pictures
        if(@objectsToDraw.num_prepictures > 0)
            pos = @objectsToDraw.current_picture - 1
            GL::Translate(-3.0,0,-6.0) # Starting position
            GL::Rotate(45.0,0,1,0)
            while pos >= 0
                @objectsToDraw.get_picture(pos).draw
                pos -= 1
                GL::Translate(-0.3,0,-1);
            end 
        end
        GL::LoadIdentity()
        # Draw post pictures
        if(@objectsToDraw.num_postpictures > 0)
            pos = @objectsToDraw.current_picture + 1
            GL::Translate(3.0,0,-6.0) # Starting position
            GL::Rotate(-45.0,0,1,0)
            while pos < @objectsToDraw.length
                @objectsToDraw.get_picture(pos).draw
                pos += 1
                GL::Translate(0.3,0,-1);
            end 
        end
        # Swap buffers for display 
    SDL.GLSwapBuffers
end


# début du script
#
#
#
SDL.init(SDL::INIT_VIDEO)
SDL.setGLAttr(SDL::GL_DOUBLEBUFFER,1)
SDL.setVideoMode(1280, 800, 0, SDL::FULLSCREEN|SDL::OPENGL|SDL::HWSURFACE)
init_gl_window(1280, 800)
@objectsToDraw = PictureCollection.new
pos = 0
Find.find(".") do |path|
    if FileTest.directory?(path) && path != "."
        Find.prune
    elsif File.extname(path) == ".jpg"
        puts path
        @objectsToDraw.add_picture Picture.new(path, pos)
        pos += 1
    end
end

# Main Loop
loop do
    event = SDL::Event2.poll
    if !event.nil?
        break if event.is_a?(SDL::Event2::Quit)
        if event.is_a?(SDL::Event2::KeyDown) # This means it's some kind of key press
            @objectsToDraw.select_next_picture if event.sym == SDL::Key::RIGHT
            @objectsToDraw.select_previous_picture if event.sym == SDL::Key::LEFT
            exit if event.sym == SDL::Key::ESCAPE
        end
    end
    draw_gl_scene
end