[Plugin] Put shadow on current day and hour

KevinKarney

Hi All
To correctly display the shadow of an object, one needs the
"Local Apparent Solar Time" - which is a function of the Sun's altitude and azimuth in the sky at your particular location. The local apparent solar time is 12:00 when the Sun is due South (or North in the Southern Hemisphere).

Your watch and your computer indicate Civil Mean Time which is related to "UTC (Universal Time Coordinated)" - which is Atomic Time (and within a hair's breadth is the same as the out-of-date Greenwich Mean Time). Atomic Time is maintained by the Bureau International des Poids et Meseurs, which is a UN Agency. It averages out the time from a large number of atomic Cesium clocks around the world

Civil Mean Time = UTC + Time Zone + Daylight Saving Hours

Local Mean Time = Civil Mean Time +/- (the Longitude difference between your time zone longitude and your local Longitude) * 4 minutes

Local Apparent Solar Time = Local Mean Time + "The Equation of Time"

The Equation of Time is the difference between mean and apparent time. There is a difference between the two, since the Mean Sun (by definition!) is a virtual object that goes around the equator at a uniform speed, while the True Sun moves around the Ecliptic (23 deg to the Equator) at a non-uniform speed (in a ellipse). I attach a graph of the Equation of Time.

Confused.... But Sketchup has all this technology built in! It's shadows are spot-on for local apparent solar time.

Check this out 1) set June 14th when the equation of time is zero. 2) set your local Latitude and Longitude. 3) Draw a vertical stick. 4) Select the time around midday when the shadow is due North or South. The time you get +/- 12 will be the difference in longitude between your time zone longitude and your local longitude * 4.

Equation of Time

pilou

@unknownuser said:

Hi Pilou! I have a free version. So yes, it could works on it!

Yes but what about good Latitude, longitude inside the free?

Matt666

Hi Pilou!
I don't know. I do some tests, and Longitude/latitude parameter is customized in menu Window/Model info->Location.
Sans titre 1.jpg
Copy and paste code below in the ruby console, you will have all shadow infos.

Sketchup.active_model.shadow_info.keys.each{|k|puts(k+"; "+Sketchup.active_model.shadow_info[k].to_s)}

Hi KevinKarney!
Sorry, but I don't understand you problem (my poor english!!)... This plugin just putd SU shadows on the current date & time... Can you tell me what I should do to correctly display the shadow of an object? Thank you! If I able to..

pilou

@Matt : this don't exist in the free
Console gives that

City: Boulder (CO)
Country: USA

Latitude: 40.017
Longitude: -105.283

ShadowTime: Fri Nov 08 14:30:00 Paris, Madrid 2002 (Normal I have this regulate at this time)
I must verify what place is
Latitude: 40.017
Longitude: -105.283

TIG

http://download.sketchup.com/OnlineDoc/gsu6_win/Content/S-Common_Tasks/Tasks-SettingLocation.htm

Explains difference between Pro and Free Location Tools...

Jim

This is my solution for version 6 Free users:

Plugin: Model Location

* This plug-in was made for SketchUp version 6 Free because it lacked the dialog (which Pro had) to change these settings. This has become ...

(sketchuptips.blogspot.com)

Version 7 Free does include the Location settings.

pilou

Thx for all these tricky solutions

Matt666

Aah, ok... Pilou uses V6!
You are completely out, man!

Gaieus

Yup,Location was not put into the free (Windows*) SU 5 and 6 but now with SU 7 it's there. Nevertheless by taking a GE snapshot, you can always "geolocate" your model (or use Jim's plugin)

*Interestingly, it was only a Windows "(un)feature" only, as the Free SU 6 for the Mac has location.

Matt666

Ok, thank you Gaieus!

@watkins said:

A brief explanation would be useful. I take it that your plugin updates shadows to the current, local time when selected. So, if I select the plugin at 15:25 Oxford UK time, the shadows show correctly for that location and time. Is that correct?
Exactly, watkins

Pout

i would at this to your script:

Sketchup.active_model.shadow_info["DisplayShadows"]=true
This will immediately also show the shadow in the model.
Otherwise one will not see the shadows if the are not set on

remus

Pout, turning on shadows as soon as you set them could be a little annoying, as it would lock SU up in a large model. Better to leave them off (if they are already off) and let the user turn them on, i reckon.

Matt666

Yep, that's why I didn't set shadows on in the code...

Pout

@remus said:

Pout, turning on shadows as soon as you set them could be a little annoying, as it would lock SU up in a large model. Better to leave them off (if they are already off) and let the user turn them on, i reckon.

True, but isn't it also a bit confusing for the user? The user sets the shadow to 'now' and i suppose that when a user does this, he wants to see the result of that action. Not?

I don't know if there are any guidelines an what to use as default behaviour on functions like this... It would be usefull to know so i can adjust some of my functions according to that guideline.

remus

I suppose if the user is using this plugin they already have a good idea of what its going to look like, so showing them isnt neccesary.

More generally, most people just use common sense.