VIEWPORT (Entity)

A viewport is a window showing a part of the model space.

You can create a single layout viewport that fits the entire layout or create multiple layout viewports in the paper space (layout).

Note

It is important to create layout viewports on their own layer. When you are ready to plot, you can turn off the layer and plot the layout without plotting the boundaries of the layout viewports. dxfwrite uses the layer VIEWPORTS as default layer for viewports.

DXFEngine.viewport(center_point, width, height, **kwargs)
Parameters:
  • center_point – center point of viewport in paper space as (x, y, z) tuple
  • width (float) – width of viewport in paper space
  • height (float) – height of viewport in paper space
  • status (int) – 0 for viewport is off, >0 ‘stacking’ order, 1 is highest priority
  • view_target_point – as (x, y, z) tuple, default value is (0, 0, 0)
  • view_direction_vector – as (x, y, z) tuple, default value is (0, 0, 0)
  • view_twist_angle (float) – in radians, default value is 0
  • view_height (float) – default value is 1
  • view_center_point – as (x, y) tuple, default value is (0, 0)
  • perspective_lens_length (float) – default value is 50
  • front_clip_plane_z_value (float) – default value is 0
  • back_clip_plane_z_value (float) – default value is 0
  • view_mode (int) – default value is 0
  • circle_zoom (int) – default value is 100
  • fast_zoom (int) – default value is 1
  • ucs_icon (int) – default value is 3
  • snap (int) – default value is 0
  • grid (int) – default value is 0
  • snap_style (int) – default value is 0
  • snap_isopair (int) – default value is 0
  • snap_angle (float) – in degrees, default value is 0
  • snap_base_point – as (x, y) tuple, default value is (0, 0)
  • snap_spacing – as (x, y) tuple, default value is (0.1, 0.1)
  • grid_spacing – as (x, y) tuple, default value is (0.1, 0.1)
  • hidden_plot (int) – default value is 0

View Mode Flags

Flags Description
VMODE_TURNED_OFF viewport is turned off if bit is set
VMODE_PERSPECTIVE_VIEW_ACTIVE viewport is in perspective mode if bit is set
VMODE_FRONT_CLIPPING_ON front clipping is on if bit is set
VMODE_BACK_CLIPPING_ON back clipping is on if bit is set
VMODE_UCS_FOLLOW_MODE_ON ???
VMODE_FRONT_CLIP_NOT_AT_EYE ???

Common Keyword Arguments for all Basic DXF R12 Entities

keyword description
layer Layer name as string
linetype Linetype name as string, if not defined = BYLAYER
color as integer in range [1..255], 0 = BYBLOCK, 256 = BYLAYER

Model space and paper space units

See also

Paper space (Layout)

Placing the Viewport

The location of the viewport in paper space is defined by the parameters center_point, width and height defines the size of the viewport, all values in paper space coordinates and units. If viewports are overlapping, the display order is defined by the status parameter (stacking order), viewports with status=2 are covered by viewports with status=1 (status=1 is the highest display priority). The viewport is always placed in the paper space by default (paper_space parameter is 1), placing in model space is possible, but does not display any content.

The viewport content

The viewport gets the content from the model space, the area to show is defined by the parameter view_target_point and view_height, because the aspect ratio of the viewport is fixed by the parameter width and height, there is no parameter view_width, all values in model space coordinates and units.

Scaling factor

Calculate the scaling factor by height divided by view_height, example: display a 50.0m model space area in a 1.0m paper space area => 1.0/50.0 => 0.02. If you want a scaling factor of 1:50 (0.02) and the model space area to display is given, calculate the necessary viewport height by view_height/50, this is correct if the model space and the paper space has the same drawing units.

Showing 3D content

  • Define the view_target_point parameter, this is the point you look at.
  • Define the view_direction_vector, this is just a direction vector, the real location in space is not important.
  • The view_center_point shifts the viewport,
  • and view_height determines the model space area to display in the viewport

Example (see also examples\viewports_in_paperspace.py):

drawing.add(
    DXFEngine.viewport(
        # location of the viewport in paper space
        center_point=(16, 10),
        # viewport width in paper space
        width=4,
        # viewport height in paper space
        height=4,
        # the model space point you look at
        view_target_point=(40, 40, 0),
        # view_direction_vector determines the view direction,
        # and it just a VECTOR, the view direction is from the location
        # of view_direction_vector to (0, 0, 0)
        view_direction_vector=(-1, -1, 1),
        # now we have a view plane (viewport) with its origin (0, 0) in
        # the view target point and view_center_point shifts
        # the center of the viewport
        view_center_point=(0, 0),
        view_height=30))
entities/viewport.png