Hi.

As posted in the images above, the star coordinates are two, and your Plug-in asks for three. Starting from the 0,0,0 origin of the SU space and the two star coordinates is enough to get the vector that points towards the star and thus make a plane point to that direction by aligning it's Zaxis to this vector. Thank you anyway for trying to help, I appreciate it.

@honoluludesktop said:

Because the plugin I am modifying contains a lot of stuff I am working on, I will pm it to you for your use only. Its too hard to clean up, and embarrassing to post here as I just left everything in. Use "my_star_pointer" beta v 1.0 at your own risk. Seems to worked on my WinXP pc, good luck with your school work, hope this is of help.

Btw, because you supply the coordinates, north shouldn't matter to the plugin, I think:-)

just a small thing. The Azimuth angle starts at north, so, can the SU north be used as this starting point? (The orange line called "North angle" in the Location Tab of the Model Info window) instead of the Y axis of the model? Hope this can be done. If not, the Y axis of SU space is fine.

@honoluludesktop said:

OK, assuming the model's yaxis is north, and at the origin of the model space, I will send you a plugin the request the coordinates of a point on a line between the star and the origin of the model space.

Any help is greatly welcomed. As you posted above, I can settle for a plug-in that can point a SU component along its Zaxis to any point selected within the SU model space. That point would be determined, as also explained above, by the two coordinates Azimuth and Altitude that take the north and horizontal plane (both included in Sketchup space) as it's reference.

To make things simpler, the coordinates of the stars would be input by hand in a SU dialog box (or similar). No need for SU to calculate nothing more, I can get this coordinates with other software for now.

@honoluludesktop said:

construsol, I took a quick looked at your link, and as I said, it is more involved then my attention span:-). I am not one of the rugy / math wizards here, but have written a plugin that does as I posted above. I will try to help you, but you can't depend on me to understand the math, or spend too much time on your project. Incidentally, no trig, differentials, factoring, etc. as the extent of my experience with ruby math is limited to equations using basic arithmetic. Sorry, no guarantees, just an offer of free help.

Hi Morisdov and thank you for jumping in to this thread. There is an updated thread here:

http://forums.sketchucation.com/viewtopic.php?f=180&t=27480

with included images hoping to make clearer explanations. I will take a closer read to your post, but let me start by saying that it is of no interest to represent the stars inside Sketchup, not in 3D or in any visual way, but to make a plane point towards specific stars at specific dates. There is a very similar plug-in that was created yersteday and updated today called "Face Sun":

http://forums.sketchucation.com/viewtopic.php?f=323&t=27499

What is needed is a plug-in that makes faces point to stars, something that can be called "Face Star". There are several ways to locate a star on the sky, one of which are Azimuth and Altitude coordinates that take North and a horizontal plane as a needed reference, both of which are already included in Sketchup. The coordinates can be obtained trough astronomy software, so the next step is to have a way that Sketchup understands where this coordinates converge according to it's North and horizontal plane, and make a selected face point towards that point. That's it.

@morisdov said:

Hello Javier,

I would start tackling this initiative with the following steps:
1) Model a very rough 3D sample archeological site using standard Sketchup tools
2) Place few Sketchup cameras inside this 3D model, pointing to assumed prpoer orientations towards the sky
Many Sketchup plugins can assist in this step, you may also take a look at my "Museum/Gallery Plugin" for Sketchup
3) Place a Dome above this model to represent the sky
4) Place on the Dome a JPEG picture texture (Sketchup "material") of the Sky of one specific point in time
5) Adjust Cameras properties looking towards the dome
6) If satisfied get additional "Sky Pictures" of more points in time to be placed on the dome
You can have many "Domes" all hidden, except one - or you can go with switching single domes texture, standard Sketchup features
7) The last step is to work out best method of generating and switching the domes texture.
There are many "visualization" tools (also available from google) to generate "pictures" out of "mathematics", i guess one that represents the sky might already be available.
8) Only if the "Dome" solution proves to be lacking must features, you may need to represent the "stars" of the sky as real 3D Sketchup objects. On this task 90% + of a programmers time
will be probably spent on understanding the mathematics and experimenting with very high precission mathematics in Sketchups scripting language "Ruby".
I believe this is the only real challenge, but first you shoud get to this step.

Cheers, Moris P.

( post links of your sites )

Dan, Thom:

Dan, you are right, years can be inputed, just seen how to do it, and thanks for the links, altough I don't have the necessary knowledge I will read them and try to be familiar with Ruby at least with this script to see if I can make adaptations to it according to own needs. Thom and Jim, thanks for the uptdate.

@dan rathbun said:

The astronomer who requested this, replied to the post at GG complaining (about Sketchup, not you ThomThom,) that's it's not easy to change the year in the Shadow info dialog. (Actually he thinks there's no way to change the year; he must have missed those left/right tick buttons.)
I replied, with this:

The Sun position would be controlled by ShadowInfo class
http://code.google.com/apis/sketchup/docs/ourdoc/shadowinfo.html

#-- Ruby
new_time = Time.gm(1981,"jan",1,20,15,1) model = Sketchup.active_model shadowinfo = model.shadow_info shadowinfo['ShadowTime']=new_time
#-- end Ruby

The Time.gm method parameters are:
(YEAR,month,day,hour,min,sec,usec)
The year is required, all others are optional and default to their minimum values.
Time.gm creates a new time object based on UTC (GMT) time.
http://www.ruby-doc.org/docs/ProgrammingRuby/html/ref_c_time.html

Info on extended Date class:
http://www.ruby-doc.org/docs/ProgrammingRuby/html/lib_standard.html
Below class Complex, scroll down ...

Thom:

I would greatly appreciate it if you can do this. Thanks again for your help.

@thomthom said:

@construsol said:

Thank you very much, this is just what I needed with the "Face Sun" Plug-in. I tested it by putting a perpendicular line to the plane that is facing the sun and it does not cast shadows, so it looks that it works great. One question, ¿How can a plane of a cube be selected and then the entire cube, not just the plane, faces the sun? Thanks again.

@thomthom said:

Made a quick plugin: http://forums.sketchucation.com/viewtopic.php?f=323&t=27499

I could make it orient the connected geometry to the selected faces. Doubt I have time until after the weekend though.

Hi Honoluludesktop.
Thank you for willing to spend some time in the development of this plug-in. It is of no interest or use to place stars in the model. The interest is to rotate a plane located in a specific geographical place and make it face a specific star. Its functionality would be like the “Face Sun” plug-in that was created today:
http://forums.sketchucation.com/viewtopic.php?f=323&t=27499
but instead of “Face Sun” it would be “Face Star”.
Also as you state, there is no practical value on rotating the entire model of an astronomical device. What I want to do is rotate a single plane of this astronomical device (not all of it) towards a star.
I will provide with all you are requesting. But before I do and just to be sure, I want to know if you already read this part of the thread:
http://forums.sketchucation.com/viewtopic.php?f=180&t=27480#p238110
in which trough images the Azimuth and Altitude coordinates system is explained. If you have not let me know if you will still need the same things you are requesting or something different. Regards.

@honoluludesktop said:

I will modify my plugin to accommodate your requirements if I have time this weekend, and you provide the following:

1. Names of variable to be input (information regarding north is here, or assumed as yaxis from point of origin as below):
2. Equations that calculate a point as x, y, z coordinates from the entire model's origin as 0,0,0 using the variables you identify above:

The plugin should work by 1. your selection of the component to be rotated along its zaxis, 2. inputing at a prompt your variables, and 3. the component will rotate and point to the coordinates you provide.

Btw, I don't understand the practical value of rotating a model of a astronomical device within the model's computer space. While what is displayed may be accurate, it may as well be arbitrary unless included with the model of the device, the model of the actual place of the device. I didn't read your entire post, as I am intellectually challenged when it comes to lengthy esoteric discussions (unless they are my own , but glad to help if possible.

Chris:

A very similar request:
http://forums.sketchucation.com/viewtopic.php?f=323&t=27477

in which a "Face sun" plug-in I needed was kindly resolved by Thomasthomas:

http://forums.sketchucation.com/viewtopic.php?f=323&t=27499

Today he made a plug-in in which if a plane is selected, it would face directly to the current sun position. Can this plug-in be of any use to start a "Face star" script? Regards.

@chris fullmer said:

Yes, it can definnitely be done. It just might be a lot of work. And I'm still trying to comprehend what you need exactly. I think you had mentioned earlier that you wanted to rotate buildings to point at a certain celestial body. That's fine, if the angles can be determined from your data (which I know it can). So what star do things align to? Is it possible to generate the coordinates automatically or read them from somewhere? Or does it have to be entered by hand?

I think what my brain is unseure of is how does the data you have match up with the model? if you have a series of coordinates, how would you tell the model what pieces align to what coordinates? Any thoughts on how that would be achieved?

Chris

That's right TIG, is almost the same as my other thread requesting a "Face sun" plug-in. As a matter of fact, Thomas was kind enough to make it today:

http://forums.sketchucation.com/viewtopic.php?f=323&t=27499

and yes, to make a Plug-in that faces stars instead of the Sun is just some math calculation away. I can provide the necesary math to convert coordinates (here is something http://en.wikipedia.org/wiki/Horizontal_coordinate_system ) and the software that calculates this coordinates depending on what star, but I don't know how to program.

@tig said:

This is parallel with your sun-tracker thread...

It's relatively straightforward to get the vector from the face's center towards a star from its two angles [azimuth and altitude] in turn derived from the time/date/location - it's basic math and/or two rotation transformations - then the face will have it's normal facing the specified star, or sun or whatever point in the sky you want...

Thank you very much, this is just what I needed with the "Face Sun" Plug-in. I tested it by putting a perpendicular line to the plane that is facing the sun and it does not cast shadows, so it looks that it works great. One question, ¿How can a plane of a cube be selected and then the entire cube, not just the plane, faces the sun? Thanks again.

@thomthom said:

Made a quick plugin: http://forums.sketchucation.com/viewtopic.php?f=323&t=27499

Hi Thomthom:

Live update is not needed, just make a plane face to a direction in which the sun would be in a specific date and time, and keep that orientation fixed even if the sun starts to move.

@thomthom said:

I got the impression live update was part of the request.

@construsol said:

. It would work like the existing feature "Face Camera"

But if a one of adjustment is all that is needed then it'd simply things - avoiding pesky observers.

Hi Chris and thank you for your reply and letting me know that it can be done. I’m sorry if in my first mail was not clear enough. You are very right on thinking how to match the data to be used with the model. Thinking on the answer, I concluded that using the Azimuth-Altitude coordinate system is better than the one I mentioned in my first mail because now there are things that are common to both SU space and star data, which can be the start of the Plug-in:

A NORTH: The Azimuth-Altitude coordinate system used to locate a star needs a geographical north (http://en.wikipedia.org/wiki/File:Azimuth_(PSF_2.svg) related to the point of observation, and the SketchUp space has this north that can be indicated in the Location section of the Model Info window. As you can see in the image of the wiki link, the Azimuth is an angular measure and starts at the north and rotates towards east. So at the north the Azimuth is 0° and at the east is 90°.

A HORIZONTAL PLANE: To have the Altitude part of a star coordinate (which is another angular measure and is also known as elevation above the horizon or elevation angle), a horizontal plane is needed, which is the one that it is located in the 0,0,0 of the X,Y,Z space coordinate system of SketchUp.

A GEOGRAPHIC LOCATION: A geographic location is needed to calculate the Azimuth and Altitude of a star to be observed in that particular location, and the SketchUp space has a geographic location that can be indicated in the Location section of the Model Info window.

With this things in common, I will try to be clearer with what I wish to have as a Plug-in with the following example, using the type of coordinates mentioned above. Let’s say I want the edge “a-b” of a plane to point to a star with an Azimuth and Altitude coordinates of 51.8° and 42.0° respectively (Fig. 1). The final result is showed in Fig. 2. Besides an edge, a plane (fig. 3) can also face a star (fig. 4). In this last case, if the star where to be the sun, it would be something like the “Always Face Camera” command but instead of looking at the camera, it would face the sun. SketchUp internally calculates the coordinates of the sun according to a geographic location, so I think is a matter of simple programming to make a plane to face it.

About what you ask about generation of the coordinates, there is a lot of free and open source software that calculate them, and it would be great if the results of the calculations that these programs can be showed inside of sketchup. Unfortunately, I’m not a programmer and don’t know if this can be done, but I can give you a list of the software that is freely available. For ease of use, it is preferred this way that to run them separately and input the coordinates by hand to a possible SU plug-in. Normally, this programs outputs in tabulated form the name and coordinates of the stars, so it would be great if this table can be looked inside of sketchup, click a particular star of the table, assign it's coordinates to an edge or plane, and see how they automatically align or face the star. Let me know if this explanation is of any help. Regards.

@chris fullmer said:

Yes, it can definnitely be done. It just might be a lot of work. And I'm still trying to comprehend what you need exactly. I think you had mentioned earlier that you wanted to rotate buildings to point at a certain celestial body. That's fine, if the angles can be determined from your data (which I know it can). So what star do things align to? Is it possible to generate the coordinates automatically or read them from somewhere? Or does it have to be entered by hand?

I think what my brain is unseure of is how does the data you have match up with the model? if you have a series of coordinates, how would you tell the model what pieces align to what coordinates? Any thoughts on how that would be achieved?

Chris

Sketchup Model

Jim:

I also think it wouldn't be hard, but I dont do Ruby, or any kind of programming. I hopping someone can help making the program or telling where I can learn to do it.

@jim said:

A plug-in does not exist as far as I know, but it wouldn't be hard to write.

How's your Ruby programming?

Thank You Pilou, but what I need is not about shadows, but about selecting a plane and rotate it in such a way that it faces the sun. Thanks for your reply.

@unknownuser said:

This one gives 45°shadows Elev45Shadows.rb by TIG
I don't know if that can help you

Hi and thank very much you for your reply.

It woul be great if the location of the point selected in space is determined by feeding it coordinates of Right Ascencion and Declination. Can this be done?

@honoluludesktop said:

Will you settle for a plugin that can point a SU component along its zaxis to any point selected within the SU model space?

Hi, this is an update of a previous topic I posted on another Forum. I included images now. Hope I can get some help here.

I'm looking for advice on how to make a plug-in or script to help on an ongoing architectural research project. If it can be done, it will prove once more the usefulness of SU for a variety of disciplines. Before I go any further and probably not making me clear with what can be a complex explanation, I just want to say that what I want to achieve with the plug in is to simply make and object point to a particular spot in space, rotating it given two specific rotating angles. That's it. I just want to use it in an automatic fashion because I will have to use many, many angles according to a specific database. Hope someone finds this interesting and help, so here it goes:

Trough what science circles call Archaeoastronomy (http://en.wikipedia.org/wiki/Archaeoastronomy), my research involves studying the relation of astronomy and architecture, both on how ancient buildings where oriented towards celestial bodies and how this can be applied today in contemporary architecture design. I'm responsible for the design and building of a "human solar clock" in the "Sol del Niño" Museum in Mexicali, Mexico, (See figure 2) and design initiative for a Public Astronomy Park, a design contest for an astronomically oriented building in Nazca, Peru (see figure 3). My theses was also about how architectural form can be determined to astronomical alignments, about how the orientation and shape of a building can be determined by aligning it toward certain stars or points where the sun rises over the horizon (please see top view of building in figure 1 below). This is my interest to reproduce and "play" within SU. For this, what I need is to have the coordinates of a celestial body so a certain object of a SU model can align to it (point to it, directed toward it).

I know that this can be done by hand, but the whole process can be done much faster with a script. So, the question is: can a script be made in which:

a) according to a specific date and geographic place of a model, a dialog window can pop up in SU like a spreadsheet that can show the coordinates of the stars according to that place and time (There is a lot of free apps that can show this coordinates according to a specific time and place, but I don’t know how to integrate it to the Location info in SU) and then

b) Assign the coordinates (they are always two) of a certain star to a certain plane(s) or object(s) of the model so it automatically aligns or points to that star?

As a reminder, the coordinates of a star in the celestial sphere are two: Declination and Right Ascension (http://www.esrl.noaa.gov/gmd/grad/solcalc/celsphere.gif). The raw data of the coordinates can be seen in figure 4, where this coordinates are the second and third columns.

Thanks in advance for any advice on how I can make this possible. Regards.

Javier

Hi.

As a follow up of my previous topic about Archaeoastronomy and Sketchup, I'm wondering if there is a Plug-in for "Face Sun". It would work like the existing feature "Face Camera", but in this case the selected plane would face directly straight to the sun in such a manner that the sun rays fall perpendicular to that plane. Thanks in advance for any info.

Hi.
I'm looking for advice on how to make a plug-in or script to help on an ongoing architectural research project. If it can be done, it will prove once more the usefulness of SU for a variety of disciplines. Before I go any further and probably not making me clear with what can be a complex explanation, I just want to say that what I want to achieve with the plug in is to simply make and object point to a particular spot in space, rotating it given two specific rotating angles. That's it. I just want to use it in an automatic fashion because I will have to use many, many angles according to a specific database. Hope someone finds this interesting and help, so here it goes:

Trough what science circles call Archaeoastronomy (http://en.wikipedia.org/wiki/Archaeoastronomy), my research involves studying the relation of astronomy and architecture, both on how ancient buildings where oriented towards celestial bodies and how this can be applied today in contemporary architecture design. I'm responsible for the design and building of a "human solar clock" in the "Sol del Niño" Museum in Mexicali, Mexico, and design initiative for a Public Astronomy Park, a design contest for an astronomically oriented building in Nazca, Peru. My theses was also about how architectural form can be partially due to astronomical alignments, about how the orientation of a building envelope components, like walls, are determined by the position o certain stars or points where the sun rises over the horizon. This is my interest to reproduce and "play" within SU. For this, what I need is to have the coordinates of a celestial body so a certain object of a SU model can align to it (point to it, directed toward it). I know that this can be done by hand, but the whole process can be done much faster with a script. So, the question is: can a script be made in which:

a) according to a specific date and geographic place of a model, a dialog window can pop up in SU like a spreadsheet that can show the coordinates of the stars according to that place and time (There is a lot of free apps that can show this coordinates according to a specific time and place, but I don’t know how to integrate it to the Location info in SU) and then

b) Assign the coordinates (they are always two) of a certain star to a certain plane(s) or object(s) of the model so it automatically aligns or points to that star?

As a reminder, the coordinates of a star in the celestial sphere are two: Declination and Right Ascension (http://www.esrl.noaa.gov/gmd/grad/solcalc/celsphere.gif).

Thanks in advance for any advice on how I can make this possible. Regards.

Javier S.