#!/usr/bin/ruby

#-----------------------------------------
# GLUTでティーポットを描画するだけのプログラム
# @author flipper
# @date   2009.03.12
#-----------------------------------------

require "rubygems"
require "opengl"
require "glut"

class Teapot
	LIGHT_POSITION = [0.25, 1.0, 0.25, 0.0]
	LIGHT_DIFFUSE  = [1.0, 1.0, 1.0]
	LIGHT_AMBIENT  = [0.25, 0.25, 0.25]
	LIGHT_SPECULAR = [1.0, 1.0, 1.0]

	MAT_DIFFUSE   = [1.0, 0.0, 0.0]
	MAT_AMBIENT   = [0.25, 0.25, 0.25]
	MAT_SPECULAR  = [1.0, 1.0, 1.0]
	MAT_SHININESS = [32.0]
	
	def reshape(w,h)
		GL.Viewport(0,0,w,h)
	
		GL.MatrixMode(GL::GL_PROJECTION)
		GL.LoadIdentity()
		GLU.Perspective(45.0, w.to_f()/h.to_f(), 0.1, 100.0)
	end

	def display()
		GL.MatrixMode(GL::GL_MODELVIEW)
		GL.LoadIdentity()
		GLU.LookAt(0.5, 1.5, 2.5, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0)
	
		GL.Lightfv(GL::GL_LIGHT0, GL::GL_POSITION, LIGHT_POSITION)
		GL.Lightfv(GL::GL_LIGHT0, GL::GL_DIFFUSE, LIGHT_DIFFUSE)
		GL.Lightfv(GL::GL_LIGHT0, GL::GL_AMBIENT, LIGHT_AMBIENT)
		GL.Lightfv(GL::GL_LIGHT0, GL::GL_SPECULAR, LIGHT_SPECULAR)

		GL.Materialfv(GL::GL_FRONT, GL::GL_DIFFUSE, MAT_DIFFUSE)
		GL.Materialfv(GL::GL_FRONT, GL::GL_AMBIENT, MAT_AMBIENT)
		GL.Materialfv(GL::GL_FRONT, GL::GL_SPECULAR, MAT_SPECULAR)
		GL.Materialfv(GL::GL_FRONT, GL::GL_SHININESS, MAT_SHININESS)
	
		GL.ClearColor(0.0, 0.0, 0.0, 1.0)
		GL.Clear(GL::GL_COLOR_BUFFER_BIT | GL::GL_DEPTH_BUFFER_BIT)

		GL.Rotate(@rotX, 1, 0, 0)
		GL.Rotate(@rotY, 0, 1, 0)
		GLUT.SolidTeapot(0.5)
	
		GLUT.SwapBuffers()
	end

	def mouse(button,state,x,y)
		if button == GLUT::GLUT_LEFT_BUTTON && state == GLUT::GLUT_DOWN then
			@start_x = x
			@start_y = y
			@drag_flg = true
		elsif state == GLUT::GLUT_UP then
			@drag_flg = false
		end
	end

	def motion(x,y)
		if @drag_flg then
			dx = x - @start_x
			dy = y - @start_y
		
			@rotY += dx
			@rotY = @rotY % 360
		
			@rotX += dy
			@rotX = @rotX % 360
		end
		@start_x = x
		@start_y = y
		GLUT.PostRedisplay()
	end

	def initialize()
		@start_x = 0
		@start_y = 0
		@rotY = 0
		@rotX = 0
		@drag_flg = false
		GLUT.InitWindowPosition(100, 100)
		GLUT.InitWindowSize(300,300)
		GLUT.Init
		GLUT.InitDisplayMode(GLUT::GLUT_DOUBLE | GLUT::GLUT_RGB | GLUT::GLUT_DEPTH)
		GLUT.CreateWindow("Ruby de OpenGL")

		GL.Enable(GL::GL_DEPTH_TEST)
		GL.Enable(GL::GL_LIGHTING)
		GL.Enable(GL::GL_LIGHT0)
	
		GL.FrontFace(GL::GL_CW)
		GL.Enable(GL::GL_AUTO_NORMAL)
		GL.Enable(GL::GL_NORMALIZE)
		GL.Enable(GL::GL_DEPTH_TEST)
		GL.DepthFunc(GL::GL_LESS)
	
		GL.ShadeModel(GL::SMOOTH)
	
		GLUT.ReshapeFunc(method(:reshape).to_proc())
		GLUT.DisplayFunc(method(:display).to_proc())
		GLUT.MouseFunc(method(:mouse).to_proc())
		GLUT.MotionFunc(method(:motion).to_proc())
	end
	
	def start()
		GLUT.MainLoop()
	end
end

Teapot.new().start()