def _generateViewport(self, fov, width, height, znear):
"""
Generates a viewport from the dimensions.
@param fov The Field of View angle (in degrees).
@param width The screen width (in pixels).
@param height The screen height (in pixels).
@param znear The z position of the near clipping plane.
@returns A tuple of (left, right, bottom, top) of the viewing frustrum at znear.
"""
# Figure out the viewport rectangle that contains the conocircle along it's shortest
# dimensions; maintain the ratio of the otherdimension.
if width < height:
znear_width = conicwidth(fov, znear)
znear_height = znear_width * height / width
else:
znear_height = conicwidth(fov, znear)
znear_width = znear_height * width / height
# Center the viewport
zleft = - 0.5 * znear_width
zright = 0.5 * znear_width
zbottom = - 0.5 * znear_height
ztop = 0.5 * znear_height
return (zleft, zright, zbottom, ztop)
def dolly( self, delta ):
"""
Executes a translate operation the z-axis.
This is equivalent of moving the camera along the z-axis; to reflect the change in view the camera will be translated by the additive inverse of the delta.
@param delta The translation delta (the change in distance along the direction vector)
"""
# We need to calculation a ratio of pixels to world units for speed.
# Get the direction vector (normalized) and the distance.
direction = self._target - self._position
distance = direction.length()
direction = direction.normalized()
# Get the view width at the point along the z-axis and build a pixels to unit ratio
viewwidth = conicwidth(self._fov, distance)
factor = viewwidth / self._screenminsize
# Calculate the translation along the direction vector
translation = direction * (- delta * factor)
# Move the Position only; the look at point reamins unchanged.
self._position += translation
self._updateProjectionMatrix()
def track( self, hdelta, vdelta ):
"""
Executes a translate operation the x-y axis.
This is equivalent of moving the scene along the x-y axis; to reflect the change in view the camera will be translated by the additive inverse of the deltas.
@param hdelta The horizontal delta (the change in distance along the right vector)
@param vdelta The vertical delta (the change in distance along the up vector)
"""
# We need to calculation a ratio of pixels to world units for speed.
# Get the direction vector (normalized) and the distance.
direction = self._target - self._position
distance = direction.length()
direction = direction.normalized()
# Get the view width at the point along the z-axis and build a pixels to unit ratio
viewwidth = conicwidth(self._fov, distance)
factor = viewwidth / self._screenminsize
# Update the right vector
right = direction ^ self._up
# Calcaulte the x-y axis translation vector
translation = right * (- hdelta * factor) + self._up * (- vdelta * factor)
# Move the Position and Target
self._position += translation
self._target += translation
self._updateProjectionMatrix()
