Sun and shadows

The sun lights the model from one direction and casts shadows, in place of the light that follows the camera. Shadows show how a building sits on its site, how deep an overhang shades a window, or where a garden gets sun. The sun is part of the model: it’s saved with it, and every change to it is an undo step.

Turn shadows on

Choose View > Shadows. The sun lights the model from where it last stood; a new model has it in the south-west, 40° above the horizon. Choose View > Shadows again to go back to the camera light.

The Sun panel

Window > Sun opens a panel you can dock with the others. At its top is the Sun tool’s button, the same one as on the toolbar and highlighted while the tool is on, a Shadows checkbox, and a switch between Real sun and By hand.

Real sun

The sun stands where it would at your site, on a date and at a time:

• Search for a city and press Enter to take the first match, or click one. About 1,250 cities are listed.
• Or click or drag on the world map to put the site anywhere. The map shades the night side of the Earth and marks where the sun is overhead. The site takes the time zone of the nearest city, and summer time follows the date, as the clocks there kept or will keep it from 2000 through 2100. Earlier and later years follow today’s rules. A site in the polar seas, beyond the map’s edge, shows on the edge with an arrow toward the pole.
• The sky chart beside the map shows the sky from below with north up: straight overhead in the middle, the horizon on the rim. The yellow line is the sun’s path for the day, with a dot every hour; the faint lines are the paths on the longest and shortest days. Drag the sun along its path to change the time.
• Drag Date through the year, or jump to an equinox or a solstice with the buttons below it.
• Drag Time through the day. The track is light between sunrise and sunset, whose times show under it. Now shows the sun as it stands at the site at this moment.

The line under the sliders gives the sun’s bearing and height, and the sunrise and sunset times. Open Coordinates to type the latitude, longitude, UTC offset or year exactly. A typed UTC offset stays as typed instead of following summer time.

By hand

Type the sun’s Azimuth and Elevation, or drag the two dials: the azimuth dial is a compass seen from above with north up, and the elevation arc is the sky seen from the side, from the horizon to straight overhead.

Dragging and undo

The view follows every drag in the panel as it happens. Releasing the button keeps the result as one undo step, so a whole drag undoes at once. Moving the sun from the panel turns shadows on. The site, date and time are kept when you switch to By hand, so switching back brings them back.

Image exports show the shadows that the view shows.

Drag the sun

Sun places the sun by hand. Click its toolbar button once to take it and again to go back to Select. While it’s active the view shows shadows, even when they’re off, and draws a dome over the model:

• a compass ring on the ground, with ticks every 30° and the letters N, E, S and W;
• the sun, a yellow handle on the dome, with its bearing and height next to it;
• a dashed line from the sun to the middle of the model, and a dotted line down to the ground beneath it.

Drag anywhere in the view and the sun moves to the point of the dome under the pointer, with the shadows following as you drag. Toward the top of the dome the sun stands high and shadows are short; toward the ring it sinks and shadows grow long. Past the edge of the dome the sun follows its outline, and it never sets below 2°. Releasing the button keeps the sun as one undo step and turns shadows on.

North is along the green axis and east along the red axis.

Type the sun’s angles

With Sun active, type the sun’s azimuth and elevation in degrees and press Enter, for example 135, 25:

• The azimuth is the compass bearing toward the sun, clockwise from north: 90 is east, 180 is south and 270 is west.
• The elevation is the sun’s height above the horizon, from 0 to 90.

Type a single number to turn the sun to that bearing and keep its height.

Placing the sun with the tool switches the panel to By hand. Turning shadows off while Sun is active puts the tool away.

What casts shadows

Opaque faces cast shadows, including faces inside groups and components. Glass and other transparent materials let the sun through. Hidden geometry, hidden objects and geometry on hidden layers cast no shadows. Geometry that an active section plane cuts away casts no shadow either, so the sun shines into a cut-open building.