indexing

	description: "[

		A scene which displayes a pyramid with OpenGL

	]"
	date: "$Date$"
	revision: "$Revision$"

class FIRST_SCENE

inherit

	EM_GL_SCENE

	GL_FUNCTIONS
		export {NONE} all end

	GLU_FUNCTIONS
		export {NONE} all end

create

	make

feature {NONE} -- Initialisation

	make is
			-- Initialise default values.
		do
			make_scene

			-- Initialise normalized speed for rotation of pyramid
			create speed
			speed.set_speed (100)
		ensure
			speed_not_void: speed /= Void
		end

feature -- Access

	angle: DOUBLE
		-- Rotation angle in degrees

	speed: EM_NORMALIZED_SPEED
		-- Rotation speed for pyramid

feature -- Drawing

	draw is
			-- Draw scene.
		do
			-- Move the pyramid into the screen and rotate it
			gl_translatef (0, 0, -9)
			gl_rotatef (angle, 0, 1, 0)

			gl_begin (Em_gl_triangles)
				-- Front
				gl_color3f(1, 0, 0) -- Red
				gl_vertex3d (0, 1, 0)
				gl_vertex3d (-1, -1, 1)
				gl_vertex3d (1, -1, 1)

				-- Right
				gl_color3f(0, 1, 0) -- Green
				gl_vertex3d (0, 1, 0)
				gl_vertex3d (1, -1, 1)
				gl_vertex3d (1, -1, -1)

				-- Back
				gl_color3f (0, 0, 1) -- Blue
				gl_vertex3d (0, 1, 0)
				gl_vertex3d (1, -1, -1)
				gl_vertex3d (-1, -1, -1)

				-- Left
				gl_color3f (1, 1, 0) -- Yellow
				gl_vertex3d (0, 1, 0)
				gl_vertex3d (-1, -1, -1)
				gl_vertex3d (-1, -1, 1)
			gl_end

			-- Increment the angle
			if angle < 360 then
				angle := angle + speed.get_delta
			else
				angle := 0
			end
		end

invariant
	speed_not_void: speed /= Void

end