Class: OpenGLCube

Inherits:
Object
  • Object
show all
Includes:
Gl, Glu, Glut
Defined in:
lib/opengl-cube.rb

Instance Method Summary collapse

Constructor Details

#initialize ⇒ OpenGLCube

Returns a new instance of OpenGLCube.



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# File 'lib/opengl-cube.rb', line 8

def initialize
  @mouse_left_button_down = false
  @mouse_right_button_down = false

  @mouse_pos_x = 0
  @mouse_pos_y = 0

  @cube_angle_x = 0
  @cube_angle_y = 0
  @cube_angle_z = 0

  # Initliaze our GLUT code
  glutInit
  # Setup a double buffer, RGBA color, alpha components and depth buffer
  glutInitDisplayMode GLUT_RGB | GLUT_DOUBLE | GLUT_ALPHA | GLUT_DEPTH
  glutInitWindowSize 640, 480
  glutInitWindowPosition 0, 0
  @window = glutCreateWindow "OpenGL Cube"
  glutDisplayFunc :draw_gl_scene
  glutReshapeFunc :reshape
  glutIdleFunc :idle
  glutKeyboardFunc :keyboard
  glutMouseFunc :mouse
  glutMotionFunc :motion
  glutPassiveMotionFunc :passive_motion
  init_gl_window 640, 480
  glutMainLoop
end

Instance Method Details

#draw_gl_scene ⇒ Object 



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# File 'lib/opengl-cube.rb', line 71

def draw_gl_scene
  # Clear the screen and depth buffer
  glClear GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT

  # Reset the view
  glMatrixMode GL_MODELVIEW
  glLoadIdentity
  # Move right 3 units
  glTranslatef 0.0, 0.0, -7.0

  # Draw a cube
  # Rotate the cube on the X, Y and Z axis
  glRotatef @cube_angle_y, 0.0, 1.0, 0.0
  glRotatef @cube_angle_x, 1.0, 0.0, 0.0
  glRotatef @cube_angle_z, 0.0, 0.0, 1.0

  # Set it to a blue color one time only
  glBegin GL_QUADS do
    # Draw the top side in green
    glColor3f 0.0, 1.0, 0.0
    glVertex3f  1.0,  1.0, -1.0
    glVertex3f -1.0,  1.0, -1.0
    glVertex3f -1.0,  1.0,  1.0
    glVertex3f  1.0,  1.0,  1.0
    # Draw the bottom side in orange
    glColor3f 1.0, 0.5, 0.0
    glVertex3f  1.0, -1.0,  1.0
    glVertex3f -1.0, -1.0,  1.0
    glVertex3f -1.0, -1.0, -1.0
    glVertex3f  1.0, -1.0, -1.0
    # Draw the front side in red
    glColor3f 1.0, 0.0, 0.0
    glVertex3f  1.0,  1.0,  1.0
    glVertex3f -1.0,  1.0,  1.0
    glVertex3f -1.0, -1.0,  1.0
    glVertex3f  1.0, -1.0,  1.0
    # Draw the back side in yellow
    glColor3f 1.0, 1.0, 0.0
    glVertex3f  1.0, -1.0, -1.0
    glVertex3f -1.0, -1.0, -1.0
    glVertex3f -1.0,  1.0, -1.0
    glVertex3f  1.0,  1.0, -1.0
    # Draw the left side in blue
    glColor3f 0.0, 0.0, 1.0
    glVertex3f -1.0,  1.0,  1.0
    glVertex3f -1.0,  1.0, -1.0
    glVertex3f -1.0, -1.0, -1.0
    glVertex3f -1.0, -1.0,  1.0
    # Draw the right side in violet
    glColor3f 1.0, 0.0, 1.0
    glVertex3f  1.0,  1.0, -1.0
    glVertex3f  1.0,  1.0,  1.0
    glVertex3f  1.0, -1.0,  1.0
    glVertex3f  1.0, -1.0, -1.0
  end

  #@pyramid_angle += 0.2
  #@cube_angle -= 0.15
  # Swap buffers for display
  glutSwapBuffers
end

#idle ⇒ Object 



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# File 'lib/opengl-cube.rb', line 133

def idle
  glutPostRedisplay
end

#init_gl_window(width = 640, height = 480) ⇒ Object 



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# File 'lib/opengl-cube.rb', line 37

def init_gl_window width = 640, height = 480
  # Background color to black
  glClearColor 0.0, 0.0, 0.0, 0
  # Enables clearing of depth buffer
  glClearDepth 1.0
  # Set type of depth test
  glDepthFunc GL_LEQUAL
  # Enable depth testing
  glEnable GL_DEPTH_TEST
  # Enable smooth color shading
  glShadeModel GL_SMOOTH

  glMatrixMode GL_PROJECTION
  glLoadIdentity
  # Calculate aspect ratio of the window
  gluPerspective 45.0, width / height, 0.1, 100.0

  glMatrixMode GL_MODELVIEW

  draw_gl_scene
end

#keyboard(key, x, y) ⇒ Object 



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# File 'lib/opengl-cube.rb', line 137

def keyboard key, x, y
  case key
  when ?\e
    glutDestroyWindow @window
    exit 0
  when ?a
    @cube_angle_y -= 15.0
  when ?d 
    @cube_angle_y += 15.0
  when ?w
    @cube_angle_x -= 15.0
  when ?s
    @cube_angle_x += 15.0
  end
  glutPostRedisplay
end

#motion(x, y) ⇒ Object 



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# File 'lib/opengl-cube.rb', line 183

def motion x, y
  if @mouse_left_button_down
    @cube_angle_y = @mouse_pos_x - x
    @cube_angle_x = @mouse_pos_y - y
  elsif @mouse_right_button_down
    @cube_angle_z = @mouse_pos_x - x
  end
end

#mouse(button, state, x, y) ⇒ Object 



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# File 'lib/opengl-cube.rb', line 154

def mouse button, state, x, y
  case button
  when GLUT_LEFT_BUTTON
    case state
    when GLUT_DOWN
    	@mouse_pos_x = x
    	@mouse_pos_y = y
    	@mouse_left_button_down = true
    when GLUT_UP 
    	@cube_angle_x = @mouse_pos_x - x
    	@cube_angle_y = @mouse_pos_y - y
    	@mouse_pos_x = x
    	@mouse_pos_y = y
      @mouse_left_button_down = false
    end
  when GLUT_RIGHT_BUTTON
    case state
    when GLUT_DOWN
      @mouse_pos_x = x
      @mouse_pos_y = y
      @mouse_right_button_down = true
    when GLUT_UP 
      @cube_angle_z = @mouse_pos_x - x
      @mouse_right_button_down = false
    end
  end
  glutPostRedisplay
end

#passive_motion(x, y) ⇒ Object 



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# File 'lib/opengl-cube.rb', line 192

def passive_motion x, y
end

#reshape(width, height) ⇒ Object 



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# File 'lib/opengl-cube.rb', line 59

def reshape width, height
  height = 1 if height == 0

  # Reset current viewpoint and perspective transformation
  glViewport 0, 0, width, height

  glMatrixMode GL_PROJECTION
  glLoadIdentity

  gluPerspective 45.0, width / height, 0.1, 100.0
end