Ah, it wasn’t clear to me that you wanted the tripod to follow the rotation of a specific object. Judging from your screenshot, I had the impression you wanted to create something like a level editor, where the tripod would indicate how the world (represented by a presumably stationary grid) was currently oriented relative to the camera. So I thought it would only need to take the rotation of the camera into account.
No worries, this is easily fixed by passing in the desired target object to the set_compass call on the tripod model.
Here’s an updated version of the code (the WorldAxesTripod class has been renamed to AxisTripod, which is a bit more general, since it’s no longer really intended to be aligned with the world/scene itself):
from direct.showbase.ShowBase import ShowBase, DirectObject
from panda3d.core import *
class AxisTripod:
def __init__(self, showbase):
self._win = showbase.win
self._dr_pixel_size = 68 # size of display region in pixels
dr = showbase.win.make_display_region(0., 1., 0., 1.)
dr.sort = 2
lens = OrthographicLens()
lens.film_size = .235
self._cam_target = cam_target = NodePath("tripod_cam_target")
cam_target.set_compass(showbase.cam)
cam_node = Camera("tripod_cam")
camera = cam_target.attach_new_node(cam_node)
camera.node().set_lens(lens)
dr.camera = camera
dr.set_clear_color_active(False)
dr.set_clear_depth_active(True)
self._display_region = dr
self._root = camera.attach_new_node("world_axes")
self._root.set_y(10.)
self.model = self.__create_model()
node = self._root.node()
node.set_bounds(OmniBoundingVolume())
node.final = True
self._listener = DirectObject.DirectObject()
self._listener.accept("aspectRatioChanged", self.__update_region_size)
def __create_model(self):
vertex_format = GeomVertexFormat.get_v3c4()
vertex_data = GeomVertexData("axis_tripod_data", vertex_format, Geom.UH_static)
pos_writer = GeomVertexWriter(vertex_data, "vertex")
col_writer = GeomVertexWriter(vertex_data, "color")
lines = GeomLines(Geom.UH_static)
for i in range(3):
v_pos = VBase3()
pos_writer.add_data3(v_pos)
v_pos[i] = .1
pos_writer.add_data3(v_pos)
color = VBase4(0., 0., 0., 1.)
color[i] = 1.
col_writer.add_data4(color)
col_writer.add_data4(color)
lines.add_vertices(i * 2, i * 2 + 1)
geom = Geom(vertex_data)
geom.add_primitive(lines)
node = GeomNode("axis_tripod")
node.add_geom(geom)
model = self._root.attach_new_node(node)
return model
def __update_region_size(self):
win_w, win_h = self._win.properties.size
aspect_ratio = win_w / win_h
size_h = self._dr_pixel_size / win_w
size_v = size_h * aspect_ratio
self._display_region.dimensions = (0., size_h, 0., size_v)
class MyApp(ShowBase):
def __init__(self):
ShowBase.__init__(self)
self.terrain = loader.loadModel('../samples/Roaming-Ralph/models/world')
self.terrain.reparentTo(render)
self._tripod = AxisTripod(self)
# make sure the tripod model follows the orientation of the terrain
self._tripod.model.set_compass(self.terrain)
self._angle = 0.
self.taskMgr.add(self.__rotate, "rotate")
def __rotate(self, task):
self._angle += 0.1
self.terrain.set_hpr(self._angle, self._angle, 0.)
return task.cont
app = MyApp()
app.run()
A task has been added that continuously changes the orientation of the terrain; you should find that the tripod follows its rotation correctly, even while rotating the camera as well.
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