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require "opengl"
require "glut"
begin
require "RMagick"
rescue Exception
print "This sample needs RMagick Module.\n"
exit
end
WIDTH = 200
HEIGHT = 200
display = Proc.new {
GL.Clear(GL::COLOR_BUFFER_BIT);
GL.Begin(GL::LINES);
GL.Vertex(0.5, 0.5);
GL.Vertex(-0.5, -0.5);
GL.End
GL.Flush();
pixel_str = GL.ReadPixels(0, 0, WIDTH, HEIGHT, GL::RGBA, GL::SHORT)
pixels = pixel_str.unpack("s*")
image = Magick::Image.new(WIDTH, HEIGHT)
image.import_pixels(0, 0, WIDTH, HEIGHT, "RGBA", pixels)
image.flip!
# image.write("opengl_window.gif")
}
reshape = Proc.new {|w, h|
GL.Viewport(0, 0, w, h);
GL.MatrixMode(GL::PROJECTION);
GL.LoadIdentity();
if (w <= h)
GLU.Ortho2D(-1.0, 1.0, -h.to_f/w.to_f, h.to_f/w.to_f);
else
GLU.Ortho2D(w.to_f/h.to_f, w.to_f/h.to_f, -1.0, 1.0);
end
GL.MatrixMode(GL::MODELVIEW);
GL.LoadIdentity();
}
# Main Loop
# Open window with initial window size, title bar,
# color index display mode, and handle input events.
#
GLUT.Init
GLUT.InitDisplayMode(GLUT::SINGLE | GLUT::RGB | GLUT::ALPHA);
GLUT.InitWindowSize(WIDTH, HEIGHT);
GLUT.CreateWindow($0);
GLUT.ReshapeFunc(reshape);
GLUT.DisplayFunc(display);
GLUT.MainLoop
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