Source code for pi3d.Camera

from __future__ import absolute_import, division, print_function, unicode_literals

import ctypes

import numpy as np
import math

from pi3d.constants import *
from pi3d.util.Utility import vec_normal, vec_cross, vec_sub, vec_dot
from pi3d.util.DefaultInstance import DefaultInstance

[docs]class Camera(DefaultInstance): """required object for creating and drawing Shape objects. Default instance created if none specified in script prior to creating a Shape """ def __init__(self, at=(0, 0, 0), eye=(0, 0, -0.1), lens=None, is_3d=True, scale=1.0, absolute=True): """Set up view matrix to look from eye to at including perspective Arguments: *at* tuple (x,y,z) location to look at *eye* tuple (x,y,z) location to look from *lens* tuple (near plane dist, far plane dist, **VERTICAL** field of view in degrees, display aspect ratio w/h) *is_3d* determines whether the camera uses a perspective or orthographic projection matrix *scale* number of pixels per unit of size for orthographic camera or divisor for fov if perspective *absolute* when True (default) then all rotations are relative to the absolute frame of reference. When False then rotations are relative to the rotated position """ super(Camera, self).__init__() = at self.start_eye = eye # for reset with different lens settings self.eye = np.array(eye) if lens is None: from pi3d.Display import Display lens = [Display.INSTANCE.near, Display.INSTANCE.far, Display.INSTANCE.fov, Display.INSTANCE.width / float(Display.INSTANCE.height)] self.lens = lens self.view = _LookAtMatrix(at, eye, [0, 1, 0]) if is_3d: self.projection = _ProjectionMatrix(lens[0], lens[1], lens[2] / scale, lens[3]) else: self.projection = _OrthographicMatrix(scale=scale) self.model_view =, self.projection) # Apply transform/rotation first, then shift into perspective space. self.mtrx = np.array(self.model_view, copy=True) # self.L_reflect = _LookAtMatrix(at,eye,[0,1,0],reflect=True) self.rtn = [0.0, 0.0, 0.0] self.scale = scale self.was_moved = True self.rotated = False self.mtrx_made = True self.absolute = absolute self.r_mtrx = np.identity(4, dtype='float32') # rotation matrix for rotations relative to rotated frame of reference self.rx = np.identity(4, dtype='float32') # hold rotation matrices for each axis self.ry = np.identity(4, dtype='float32') self.rz = np.identity(4, dtype='float32') self.t1 = np.identity(4, dtype='float32') # translation applied prior to rotation i.e. for stereo effect self.t2 = np.identity(4, dtype='float32') # translation applied after rotation i.e. actual position @staticmethod def _default_instance(): from pi3d.Display import Display return Camera((0, 0, 0), (0, 0, -0.1), [Display.INSTANCE.near, Display.INSTANCE.far, Display.INSTANCE.fov, Display.INSTANCE.width / float(Display.INSTANCE.height)])
[docs] def reset(self, lens=None, is_3d=True, scale=1.0): """Has to be called each loop if the camera position or rotation changes""" if lens is not None: view = _LookAtMatrix(, self.start_eye, [0, 1, 0]) projection = _ProjectionMatrix(lens[0], lens[1], lens[2] / scale, lens[3]) self.model_view =, projection) elif not is_3d: view = _LookAtMatrix(, self.start_eye, [0, 1, 0]) projection = _OrthographicMatrix(scale=scale) self.model_view =, projection) # TODO some way of resetting to original matrix self.mtrx = np.copy(self.model_view) self.rtn = [0.0, 0.0, 0.0] self.scale = scale self.was_moved = True
[docs] def point_at(self, target=[0.0, 0.0, 10000.0]): """ point the camera at a point also return the tilt and rotation values Keyword argument: *target* Location as [x,y,z] array to point at, defaults to a high +ve z value as a kind of compass! """ if target[0] == self.eye[0] and target[1] == self.eye[1] and target[2] == self.eye[2]: return dx, dy, dz = target[0] - self.eye[0], target[1] - self.eye[1], target[2] - self.eye[2] rot = -math.degrees(math.atan2(dx, dz)) horiz = (dx * dx + dz * dz) ** 0.5 tilt = math.degrees(math.atan2(dy, horiz)) self.rotate(tilt, rot, 0) return tilt, rot
[docs] def get_direction(self): """ returns the direction that the Camera is pointing as a numpy unit vector [x,y,z] this can be used directly for positioning the view position without resorting to trig functions. Also see relocate() """ if not self.rotated: self._make_r_mtrx() return self.r_mtrx[0:3,2]
[docs] def relocate(self, rot=None, tilt=None, point=np.array([0.0, 0.0, 0.0]), distance=np.array([0.0, 0.0, 0.0]), normal=None, slope_factor=0.5, crab=False): """ A convenience function for frequently used Camera animation steps. The camera is reset and the rotation and tilt are applied. If a normal is not supplied the camera is positioned using the distance and point vectors. If there is a normal then the camera is moved to the point and the new position relative to this is returned. This behaviour allows the y coordinate to be subsequently adjusted (in the calling program) using ElevationMap.calcHeight() The normal vector is also used in conjunction with the slope_factor to determine an adjustment to the distance moved each frame. *rot* absolute y rotation of the Camera *tilt* x rotation *point* 3D vector to move relative to (or to if normal is None) *distance* 3D vector from point to Camera *normal* 3D vector normal to surface at point *slope_factor* effect of normal vector on movement *crab* if True then distance is horizontally at right angles to direction that the Camera is pointing """ self.reset() if tilt is not None: self.rotateX(tilt) if rot is not None: self.rotateY(rot) if not self.rotated: self._make_r_mtrx() direction = self.r_mtrx[0:3,2] # NB this is different from the direction vector in self.mtrx if crab: direction = np.cross(direction, [0.0, 1.0, 0.0]) # horizontal sideways if normal is None: # move the camera to new location now new_point = direction * distance + point self.position(new_point) return new_point else: # move the camera to old position but return new position (for height adjustment) self.position(point) # resultant in x,z plane netf =[[0,2]], (normal[[0,2]] * slope_factor)) if netf > -1.0: return direction * distance * (1.0 + netf) + point return point # otherwise don't move!
[docs] def position(self, pt): """position camera Arguments: *pt* tuple (x, y, z) floats """ self.eye = np.array(pt) self.t2[3,:3] = -self.eye #self.mtrx =, self.mtrx) self.was_moved = True self.mtrx_made = False
def _rotate_axis(self, angle, k0, k1, k2, k3): ''' similar job needed for each axis but with different signs ''' c = math.cos(math.radians(angle)) s = math.sin(math.radians(angle)) self.was_moved = True self.mtrx_made = False self.rotated = False return [[k0 * c, k1 * s], [k2 * s, k3 * c]]
[docs] def rotateZ(self, angle): """Rotate camera z axis Arguments: *angle* in degrees """ self.rz[0:2,0:2] = self._rotate_axis(angle, 1, 1, -1, 1) self.rtn[2] = angle
[docs] def rotateY(self, angle): """Rotate camera y axis Arguments: *angle* in degrees """ self.ry[0:3:2,0:3:2] = self._rotate_axis(angle, 1, -1, 1, 1) self.rtn[1] = angle
[docs] def rotateX(self, angle): """Rotate camera x axis Arguments: *angle* in degrees """ self.rx[1:3,1:3] = self._rotate_axis(angle, 1, 1, -1, 1) self.rtn[0] = angle
[docs] def rotate(self, rx, ry, rz): """Rotate camera Arguments: *rx* x rotation in degrees *ry* y rotation in degrees *rz* z rotation in degrees """ self.rotateZ(rz) self.rotateX(rx) self.rotateY(ry)
[docs] def offset(self, pt): """position camera Arguments: *pt* tuple (x, y, z) floats """ self.t1[3,:3] = -np.array(pt) self.was_moved = True self.mtrx_made = False
[docs] def make_mtrx(self): if not self.rotated: self._make_r_mtrx() self.mtrx =,,, self.mtrx))) self.mtrx_made = True
def _make_r_mtrx(self): if self.absolute: self.r_mtrx = np.identity(4, dtype='float32') self.r_mtrx =,,, self.rz))) self.rotated = True
[docs] def euler_angles(self, matrix=None): ''' Or more correctly Tait-Bryan angles. Argument *matrix* can supply a rotation matrix to use (as generated by the following method.) Defaults to using the Camera.r_mtrx in pi3d arrangement (C type and Z into screen):: sx`` ''' m = matrix if matrix is not None else self.r_mtrx # alias for clarity rx = math.asin(m[1,2]) cx = math.cos(rx) if cx != 0.0: ry = math.atan2(-m[0,2], m[2,2]) else: ry = math.pi / 2.0 rz = math.atan2(-m[1,0], m[1,1]) return math.degrees(rx), math.degrees(ry), math.degrees(rz)
[docs] def matrix_from_two_vecors(self, start_vector, vector): ''' uses two 3D vectors (arrays) to generate a rotation vector representing the movement from one direction to another. NB because there are many ways of doing this the z rotation may not match so this this method might be best combined with the euler_angles system above. See the pi3d_demos/ example - key press 'k' ''' start_vector /= ((start_vector ** 2).sum()) ** 0.5 # convert to unit length vector /= ((vector ** 2).sum()) ** 0.5 axis = np.cross(vector, start_vector) axis /= ((axis ** 2).sum()) ** 0.5 # sine of angle, for some reason has to be assigned to cos value i.e. # the angle is complementary to the expected one. Not really sure why this is! c =, vector) angle = math.asin(c) # angle in radians x, y, z = axis[0:3] # aliases for clarity in matrix below s = math.cos(angle) # see comment above about using a = 90-a t = 1.0 - c return np.array([ [t*x*x + c, t*y*x + z*s, t*x*z - y*s, 0.0], # 1 [t*x*y - z*s, t*y*y + c, t*y*z + x*s, 0.0], # 2 [t*x*z + y*s, t*y*z - x*s, t*z*z + c, 0.0], # 3 [0.0, 0.0, 0.0, 1.0]], dtype='float')
################################# ####### utility functions ####### def _LookAtMatrix(at, eye, up=[0, 1, 0], reflect=False): """Define a matrix looking at. Arguments: *at* tuple (x,y,z) of point camera pointed at, floats *eye* matrix [x,y,z] position of camera, floats Keyword arguments: *up* array vector of up direction *eflect* boolean if matrix is reflected """ # If reflect, then reflect in plane -20.0 (water depth) if reflect: depth = -20.0 # Shallower to avoid edge effects eye[1] *= -1 at[1] *= -1 zaxis = vec_normal(vec_sub(at, eye)) xaxis = vec_normal(vec_cross(up, zaxis)) yaxis = vec_cross(zaxis, xaxis) xaxis.append(-vec_dot(xaxis, eye)) yaxis.append(-vec_dot(yaxis, eye)) zaxis.append(-vec_dot(zaxis, eye)) z = [0, 0, 0, 1.0] return np.array([[xaxis[a], yaxis[a], zaxis[a], z[a]] for a in range(4)], dtype="float32") def _ProjectionMatrix(near, far, fov, aspectRatio): """Set up perspective projection matrix Keyword arguments: *near* distance to near plane, float *far* distance to far plane, float *fov* **VERTICAL** field of view in degrees, float *aspectRatio* aspect ratio = width / height of the scene, float """ # Matrices are considered to be M[row][col] # Use DirectX convention, so need to do rowvec*Matrix to transform size = 1 / math.tan(math.radians(fov)/2.0) M = np.zeros((4, 4), dtype="float32") M[0,0] = size/aspectRatio M[1,1] = size #negative value reflects scene on the Y axis M[2,2] = (far + near) / (far - near) M[2,3] = 1 M[3,2] = -(2 * far * near)/(far - near) return M def _OrthographicMatrix(scale=1.0): """Set up orthographic projection matrix Keyword argument: *scale* number of pixels per unit of size """ from pi3d.Display import Display M = np.zeros((4, 4), dtype="float32") M[0,0] = 2.0 * scale / Display.INSTANCE.width M[1,1] = 2.0 * scale / Display.INSTANCE.height #M[2,2] = 2.0 / Display.INSTANCE.width M[2,2] = 2.0 / 10000.0 M[3,2] = -1 M[3,3] = 1 return M