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Hi there,
I'm a recent convert from Python, PHP et al., and aside from more
serious web-related development with Rails, have been playing a bit
with Yoshi's OpenGL/GLUT bindings. I was interested to see how
ruby-opengl performance would compare with C/C++, so I wrote a Ruby
version of the (in)famous spinning 3D gear wheels demo program, which
is often used as a simple benchmark for OpenGL.
(Kudos to Yoshi for the OpenGL bindings: translating from the original
C code was straightforward and only took an hour or so to finish.)
The results were a bit surprising, in a good way. On my Linux computer
with ATI Radeon 9700, the compiled version of the original gears.c
gives an average 1271 FPS, whereas the gears.rb version achieves an
average of 1203 FPS. (Both programs were run for a couple of minutes
and results averaged.) That's only a 6% gap in performance.
Granted this is a fairly simple OpenGL app, but it's certainly easy to
imagine how productive programmers of open-source games, simulations
etc. could be writing Ruby instead of C/C++ as is the norm.
I've attached the Ruby file gears.rb. It only requires the ruby-opengl
extension to run. The code was translated from rev 1.8 of the
GLUT-based gears.c (not the same as glxgears!) included in the Mesa 3D
software package, keeping the structure close to the original, but
wrapping it in a Ruby class. I also added some simple code to do mouse
rotation. If anyone wishes to compare performance with the original
version, it can downloaded from:
http://cvs.freedesktop.org/mesa/Mesa/progs/demos/gears.c
Arto Bendiken
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#!/usr/bin/env ruby
# 3-D gear wheels. This program is in the public domain.
#
# Command line options:
# -info print GL implementation information
# -exit automatically exit after 30 seconds
#
# 2005-05-01 Ruby version by Arto Bendiken based on gears.c rev 1.8.
# 2005-01-09 Original C version (gears.c) by Brian Paul et al.
# http://cvs.freedesktop.org/mesa/Mesa/progs/demos/gears.c?rev8
require 'opengl'
require 'glut'
class Gears
POS 5.0, 5.0, 10.0, 0.0]
RED 0.8, 0.1, 0.0, 1.0]
GREEN 0.0, 0.8, 0.2, 1.0]
BLUE 0.2, 0.2, 1.0, 1.0]
include Math
# Draw a gear wheel. You'll probably want to call this function when
# building a display list since we do a lot of trig here.
#
# Input: inner_radius - radius of hole at center
# outer_radius - radius at center of teeth
# width - width of gear
# teeth - number of teeth
# tooth_depth - depth of tooth
def gear(inner_radius, outer_radius, width, teeth, tooth_depth)
r0 nner_radius
r1 uter_radius - tooth_depth / 2.0
r2 uter_radius + tooth_depth / 2.0
da .0 * PI / teeth / 4.0
GL.ShadeModel(GL::FLAT)
GL.Normal(0.0, 0.0, 1.0)
# Draw front face
GL.Begin(GL::QUAD_STRIP)
for i in 0..teeth
angle * 2.0 * PI / teeth
GL.Vertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5)
GL.Vertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5)
if i < teeth
GL.Vertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5)
GL.Vertex3f(r1 * cos(angle + 3 * da),
r1 * sin(angle + 3 * da), width * 0.5)
end
end
GL.End()
# Draw front sides of teeth
GL.Begin(GL::QUADS)
for i in 0...teeth
angle * 2.0 * PI / teeth
GL.Vertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5)
GL.Vertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5)
GL.Vertex3f(r2 * cos(angle + 2 * da),
r2 * sin(angle + 2 * da), width * 0.5)
GL.Vertex3f(r1 * cos(angle + 3 * da),
r1 * sin(angle + 3 * da), width * 0.5)
end
GL.End()
GL.Normal(0.0, 0.0, -1.0)
# Draw back face
GL.Begin(GL::QUAD_STRIP)
for i in 0..teeth
angle * 2.0 * PI / teeth
GL.Vertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5)
GL.Vertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5)
if i < teeth
GL.Vertex3f(r1 * cos(angle + 3 * da),
r1 * sin(angle + 3 * da), -width * 0.5)
GL.Vertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5)
end
end
GL.End()
# Draw back sides of teeth
GL.Begin(GL::QUADS)
for i in 0...teeth
angle * 2.0 * PI / teeth
GL.Vertex3f(r1 * cos(angle + 3 * da),
r1 * sin(angle + 3 * da), -width * 0.5)
GL.Vertex3f(r2 * cos(angle + 2 * da),
r2 * sin(angle + 2 * da), -width * 0.5)
GL.Vertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5)
GL.Vertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5)
end
GL.End()
# Draw outward faces of teeth
GL.Begin(GL::QUAD_STRIP)
for i in 0...teeth
angle * 2.0 * PI / teeth
GL.Vertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5)
GL.Vertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5)
u 2 * cos(angle + da) - r1 * cos(angle)
v 2 * sin(angle + da) - r1 * sin(angle)
len qrt(u * u + v * v)
u / en
v / en
GL.Normal(v, -u, 0.0)
GL.Vertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5)
GL.Vertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5)
GL.Normal(cos(angle), sin(angle), 0.0)
GL.Vertex3f(r2 * cos(angle + 2 * da),
r2 * sin(angle + 2 * da), width * 0.5)
GL.Vertex3f(r2 * cos(angle + 2 * da),
r2 * sin(angle + 2 * da), -width * 0.5)
u 1 * cos(angle + 3 * da) - r2 * cos(angle + 2 * da)
v 1 * sin(angle + 3 * da) - r2 * sin(angle + 2 * da)
GL.Normal(v, -u, 0.0)
GL.Vertex3f(r1 * cos(angle + 3 * da),
r1 * sin(angle + 3 * da), width * 0.5)
GL.Vertex3f(r1 * cos(angle + 3 * da),
r1 * sin(angle + 3 * da), -width * 0.5)
GL.Normal(cos(angle), sin(angle), 0.0)
end
GL.Vertex3f(r1 * cos(0), r1 * sin(0), width * 0.5)
GL.Vertex3f(r1 * cos(0), r1 * sin(0), -width * 0.5)
GL.End()
GL.ShadeModel(GL::SMOOTH)
# Draw inside radius cylinder
GL.Begin(GL::QUAD_STRIP)
for i in 0..teeth
angle * 2.0 * PI / teeth
GL.Normal(-cos(angle), -sin(angle), 0.0)
GL.Vertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5)
GL.Vertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5)
end
GL.End()
end
def draw
GL.Clear(GL::COLOR_BUFFER_BIT | GL::DEPTH_BUFFER_BIT);
GL.PushMatrix()
GL.Rotate(@view_rotx, 1.0, 0.0, 0.0)
GL.Rotate(@view_roty, 0.0, 1.0, 0.0)
GL.Rotate(@view_rotz, 0.0, 0.0, 1.0)
GL.PushMatrix()
GL.Translate(-3.0, -2.0, 0.0)
GL.Rotate(@angle, 0.0, 0.0, 1.0)
GL.CallList(@gear1)
GL.PopMatrix()
GL.PushMatrix()
GL.Translate(3.1, -2.0, 0.0)
GL.Rotate(-2.0 * @angle - 9.0, 0.0, 0.0, 1.0)
GL.CallList(@gear2)
GL.PopMatrix()
GL.PushMatrix()
GL.Translate(-3.1, 4.2, 0.0)
GL.Rotate(-2.0 * @angle - 25.0, 0.0, 0.0, 1.0)
GL.CallList(@gear3)
GL.PopMatrix()
GL.PopMatrix()
GLUT.SwapBuffers()
@frames if not defined? @frames
@t0 if not defined? @t0
@frames +
t LUT.Get(GLUT::ELAPSED_TIME)
if t - @t0 > 000
seconds t - @t0) / 1000.0
fps frames / seconds
printf("%d frames in %6.3f seconds 6.3f FPS\n",
@frames, seconds, fps)
@t0, @frames , 0
exit if defined? @autoexit and t > 99.0 * @autoexit
end
end
def idle
t LUT.Get(GLUT::ELAPSED_TIME) / 1000.0
@t0_idle if !defined? @t0_idle
# 90 degrees per second
@angle + 0.0 * (t - @t0_idle)
@t0_idle
GLUT.PostRedisplay()
end
# Change view angle, exit upon ESC
def key(k, x, y)
case k
when ?z
@view_rotz + .0
when ?Z
@view_rotz - .0
when 27 # Escape
exit
end
GLUT.PostRedisplay()
end
# Change view angle
def special(k, x, y)
case k
when GLUT::KEY_UP
@view_rotx + .0
when GLUT::KEY_DOWN
@view_rotx - .0
when GLUT::KEY_LEFT
@view_roty + .0
when GLUT::KEY_RIGHT
@view_roty - .0
end
GLUT.PostRedisplay()
end
# New window size or exposure
def reshape(width, height)
h eight.to_f / width.to_f
GL.Viewport(0, 0, width, height)
GL.MatrixMode(GL::PROJECTION)
GL.LoadIdentity()
GL.Frustum(-1.0, 1.0, -h, h, 5.0, 60.0)
GL.MatrixMode(GL::MODELVIEW)
GL.LoadIdentity()
GL.Translate(0.0, 0.0, -40.0)
end
def init
@angle .0
@view_rotx, @view_roty, @view_rotz 0.0, 30.0, 0.0
GL.Lightfv(GL::LIGHT0, GL::POSITION, POS)
GL.Enable(GL::CULL_FACE)
GL.Enable(GL::LIGHTING)
GL.Enable(GL::LIGHT0)
GL.Enable(GL::DEPTH_TEST)
# Make the gears
@gear1 L.GenLists(1)
GL.NewList(@gear1, GL::COMPILE)
GL.Material(GL::FRONT, GL::AMBIENT_AND_DIFFUSE, RED)
gear(1.0, 4.0, 1.0, 20, 0.7)
GL.EndList()
@gear2 L.GenLists(1)
GL.NewList(@gear2, GL::COMPILE)
GL.Material(GL::FRONT, GL::AMBIENT_AND_DIFFUSE, GREEN)
gear(0.5, 2.0, 2.0, 10, 0.7)
GL.EndList()
@gear3 L.GenLists(1)
GL.NewList(@gear3, GL::COMPILE)
GL.Material(GL::FRONT, GL::AMBIENT_AND_DIFFUSE, BLUE)
gear(1.3, 2.0, 0.5, 10, 0.7)
GL.EndList()
GL.Enable(GL::NORMALIZE)
ARGV.each do |arg|
case arg
when '-info'
printf("GL_RENDERER s\n", GL.GetString(GL::RENDERER))
printf("GL_VERSION s\n", GL.GetString(GL::VERSION))
printf("GL_VENDOR s\n", GL.GetString(GL::VENDOR))
printf("GL_EXTENSIONS s\n", GL.GetString(GL::EXTENSIONS))
when '-exit'
@autoexit 0
printf("Auto Exit after %i seconds.\n", @autoexit);
end
end
end
def visible(vis)
GLUT.IdleFunc((vis GLUT::VISIBLE ? method(:idle).to_proc : nil))
end
def mouse(button, state, x, y)
@mouse tate
@x0, @y0 , y
end
def motion(x, y)
if @mouse GLUT::DOWN then
@view_roty + x0 - x
@view_rotx + y0 - y
end
@x0, @y0 , y
end
def initialize
GLUT.Init()
GLUT.InitDisplayMode(GLUT::RGB | GLUT::DEPTH | GLUT::DOUBLE)
GLUT.InitWindowPosition(0, 0)
GLUT.InitWindowSize(300, 300)
GLUT.CreateWindow('Gears')
init()
GLUT.DisplayFunc(method(:draw).to_proc)
GLUT.ReshapeFunc(method(:reshape).to_proc)
GLUT.KeyboardFunc(method(:key).to_proc)
GLUT.SpecialFunc(method(:special).to_proc)
GLUT.VisibilityFunc(method(:visible).to_proc)
GLUT.MouseFunc(method(:mouse).to_proc)
GLUT.MotionFunc(method(:motion).to_proc)
end
def start
GLUT.MainLoop()
end
end
Gears.new.start
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