rubyでOpenGLの練習してます。とりあえず、四角形がマウスについてくるようなものを作って見ました。

[code lang=ruby]
require "rubygems"
require "opengl"
require "glut"

mouseX = 0
mouseY = 0

display = Proc.new{
GL.Clear GL_COLOR_BUFFER_BIT

# draw rect
GL.Color3d 1.0, 1.0, 0.0
GL.PushMatrix
GL.Translatef mouseX, mouseY, 0
GL.Begin GL_POLYGON
GL.Vertex2d 0, 0
GL.Vertex2d 0, 20
GL.Vertex2d 20, 20
GL.Vertex2d 20, 0
GL.End
GL.PopMatrix

GL.Flush
GLUT.SwapBuffers
}

resize = Proc.new{|w,h|
GL.Viewport 0, 0, w, h
GL.LoadIdentity
GL.Ortho 0.0, w, h, 0.0, -1.0, 1.0
}

mouse_move = Proc.new{|x,y|
mouseX = x
mouseY = y
GLUT.PostRedisplay
}

def init
GL.ClearColor 0.0, 0.0, 0.0, 1.0
end

GLUT.Init
GLUT.InitDisplayMode GLUT_RGBA
GLUT.InitWindowSize 640, 480
GLUT.InitWindowPosition 0, 0
GLUT.CreateWindow "OpenGL:test"
GL.Clear GL_COLOR_BUFFER_BIT
GLUT.DisplayFunc display
GLUT.ReshapeFunc resize
GLUT.PassiveMotionFunc mouse_move
init
GLUT.MainLoop
[/code]