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# Soya 3D tutorial
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# Copyright (C) 2004 Jean-Baptiste LAMY
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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# basic-6: Event management : a mouse-controlled caterpillar
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# This time, we'll use the mouse to control the caterpillar.
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# Import the Soya module.
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import sys, os, os.path, soya, soya.sdlconst
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soya.init()
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soya.path.append(os.path.join(os.path.dirname(sys.argv[0]), "data"))
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# Creates a scene.
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scene = soya.World()
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# The CaterpillarHead class is very similar to the CaterpillarHead class of the previous
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# lesson.
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class CaterpillarHead(soya.Volume):
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  def __init__(self, parent):
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    soya.Volume.__init__(self, parent, soya.Shape.get("caterpillar_head"))
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    self.speed                  = soya.Vector(self, 0.0, 0.0, 0.0)
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    self.rotation_lateral_speed = 0.0
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    self.mouse_x                = 0
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    self.mouse_y                = 0
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  def begin_round(self):
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    soya.Volume.begin_round(self)
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    # Loops over all Soya / SDL events.
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    for event in soya.process_event():
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      # Checks for mouse motion events, and store the mouse cursor X, Y coordinates.
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      if event[0] == soya.sdlconst.MOUSEMOTION:
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        self.mouse_x = event[1]
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        self.mouse_y = event[2]
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    # Computes the mouse coordinates in 3D. Camera.coord2d_to_3d takes the X and Y mouse 2D
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    # coordinates, and an optional Z coordinates (as it canoot guess the third coordinate ;
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    # Z default to -1.0).
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    # Here, we use for Z the Z coordinates of the caterpillar in the camera coordinate
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    # system: we consider the mouse cursor to be at the same depth that the caterpillar.
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    # The % operator is used for coordinate system conversion:
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    #     position % coordinate_system
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    # returns position converted into coordinate_system (possibly position itself if it
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    # is already in the right coordinate system).
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    mouse_pos = camera.coord2d_to_3d(self.mouse_x, self.mouse_y, (self % camera).z)
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    # Then, converts the mouse position into the scene coordinate system, and set its Y
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    # coordinate to 0.0, because we don't want the caterpillar to start flying !
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    # (remember, Y is the upper direction).
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    mouse_pos.convert_to(scene)
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    mouse_pos.y = 0.0
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    # Computes the speed Z coordinate ; we don't want a constant speed: the farther the
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    # mouse cursor is, the faster the caterpillar moves.
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    # Thus the speed Z coordinate is the distance from the caterpillar to the mouse,
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    # and it must be negative (cause -Z is front).
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    self.speed.z = -self.distance_to(mouse_pos)
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    # Rotations toward the mouse.
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    self.look_at(mouse_pos)
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  def advance_time(self, proportion):
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    soya.Volume.advance_time(self, proportion)
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    self.add_mul_vector(proportion, self.speed)
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# We change CaterpillarPiece, so it can deal with the variable-speed head.
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class CaterpillarPiece(soya.Volume):
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  def __init__(self, parent, previous):
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    soya.Volume.__init__(self, parent, soya.Shape.get("caterpillar"))
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    self.previous = previous
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    self.speed = soya.Vector(self, 0.0, 0.0, -0.2)
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  def begin_round(self):
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    soya.Volume.begin_round(self)
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    # As the speed can be very high, we need to take into account the speed of the previous
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    # piece (the one we are moving toward).
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    # Computes the next position of the previous piece, by translating the piece by the
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    # piece's speed vector.
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    previous_next_pos = self.previous + self.previous.speed
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    # Looks toward the previous piece's next position.
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    self.look_at(previous_next_pos)
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    # Computes the speed's Z coordinate. We use the distance between this piece and the
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    # next position of the previous one, and we remove 1.5 because we want each piece
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    # to be sepaarated by 1.5 distance units.
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    self.speed.z = -(self.distance_to(previous_next_pos) - 1.5)
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  def advance_time(self, proportion):
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    soya.Volume.advance_time(self, proportion)
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    self.add_mul_vector(proportion, self.speed)
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# Creates a caterpillar head and 10 caterpillar piece of body.
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caterpillar_head = CaterpillarHead(scene)
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caterpillar_head.rotate_lateral(90.0)
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previous_caterpillar_piece = caterpillar_head
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for i in range(10):
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  previous_caterpillar_piece = CaterpillarPiece(scene, previous_caterpillar_piece)
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  previous_caterpillar_piece.x = i + 1
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# Creates a light.
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light = soya.Light(scene)
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light.set_xyz(2.0, 5.0, 1.0)
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# Creates a camera.
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camera = soya.Camera(scene)
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camera.set_xyz(0.0, 15.0, 15.0)
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camera.look_at(caterpillar_head)
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soya.set_root_widget(camera)
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soya.Idler(scene).idle()
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