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Old 06-19-2019, 11:00 PM   #11
Michael Thayne
 
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Default Re: [Magic] Using Shape Earth and Earth to Stone in construction

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Originally Posted by GURPSman View Post
If if the GM ruled the rocks can't be fused together via Shape Earth, it's not much of a limitation. Simple dovetail joints, finger joints, pegs, joists, arches, and various basic techniques could create massive structures from many parts.
So I've been reading up on the history of architecture, and my understanding is that the civilizations GURPS calls TL1 (including Egyptians, Aztecs, and Mesopotamians) basically lacked the ability to build large stone-roofed chambers. All three civilizations built huge pyramids, but the interior chambers were small or nonexistent. This is because they may have used corbeled arches but didn't understand the value of the true arch. Now if you magically fuse the slabs of a corbeled arch, I think it would effectively become a true arch. Is the same true if you merely used Shape Earth to connect the stones making up your corbeled arch with fancy joints not normally possible in masonry? I'm not sure.

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Also, a clever player could simply fuse molten rocks together with the Fire college-at least with the Heat spell at skill 15.
Oh thanks, didn't read the Heat spell description closely enough.
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Old 06-19-2019, 11:25 PM   #12
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Default Re: [Magic] Using Shape Earth and Earth to Stone in construction

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Now if you magically fuse the slabs of a corbeled arch, I think it would effectively become a true arch.
Nope, the distinctive feature of the true arch is its shape, not how it's held together. Shape earth would make construction of a corbeled arch somewhat easier, but it's basically math to figure out a true arch (side point: the 'find weakness' spell would probably let you build a true arch by trial and error, because stress points should show up as weaknesses).
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Old 06-20-2019, 12:30 AM   #13
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Default Re: [Magic] Using Shape Earth and Earth to Stone in construction

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Related question: How can power-based Shape Earth be improved to match the skill-based one?
I think we'd need some custom rules. Since levels of Control do more than just increase the weight limit (P91 it also increases the elongate/flow Move speed...that's all I could find) then there should probably be limitations (like when you buy levels of Telekinesis) which only affect one thing the levels do or the other (weight or flow speed).

P83 has the custom TK limitation "Lift Only" where it only affects weight but not movement speed, while "Move Only" does the opposite.

I don't know if 20/40 would be the correct numbers to use for Control, but it's an idea to build from.
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Old 06-20-2019, 05:42 AM   #14
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Default Re: [Magic] Using Shape Earth and Earth to Stone in construction

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Originally Posted by Michael Thayne View Post
So I've been reading up on the history of architecture, and my understanding is that the civilizations GURPS calls TL1 (including Egyptians, Aztecs, and Mesopotamians) basically lacked the ability to build large stone-roofed chambers. All three civilizations built huge pyramids, but the interior chambers were small or nonexistent. This is because they may have used corbeled arches but didn't understand the value of the true arch. Now if you magically fuse the slabs of a corbeled arch, I think it would effectively become a true arch. Is the same true if you merely used Shape Earth to connect the stones making up your corbeled arch with fancy joints not normally possible in masonry? I'm not sure.
A TL1 mason with hammer and chisel would have an extremely difficult time making those fine joints in hard but brittle stone. Also the mason and labors transporting, lifting, and fitting those joints would have a good chance of breaking them.

Shape Earth (stone) can make complex shapes in a matter of seconds. Shape Earth (stone) also moves the stone and shapes it in place without the need to transport (an important limitation at low TLs). Other spells that are useful in building are Essential Earth tripled the strength of the joints. Earth wizards has tremendous capacity to build and construct very quickly.

Last edited by GURPSman; 06-20-2019 at 06:31 AM.
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Old 06-20-2019, 07:45 AM   #15
Michael Thayne
 
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Default Re: [Magic] Using Shape Earth and Earth to Stone in construction

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Nope, the distinctive feature of the true arch is its shape, not how it's held together. Shape earth would make construction of a corbeled arch somewhat easier, but it's basically math to figure out a true arch (side point: the 'find weakness' spell would probably let you build a true arch by trial and error, because stress points should show up as weaknesses).
I'm looking at this image on Wikipedia. The difference is entirely in the shape of the stones—the image on the left has wedge-shaped stones, including the familiar wedge-shaped keystone, whereas the image on the right has a roughly rectangular stone where its keystone should be, which is held in place mainly by mortar. I don't know the details, but I'm pretty sure mortar isn't as strong as the original rock. If you could magically fuse the elements of the right image together, though, now you have something that should be equivalent to a naturally-occurring arch, which I think are as strong as masonry arches with wedge-shaped components.
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Old 06-20-2019, 10:36 AM   #16
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Default Re: [Magic] Using Shape Earth and Earth to Stone in construction

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I'm looking at this image on Wikipedia. The difference is entirely in the shape of the stones
Oh, I was misremembering true arch. Fusing the stones should get the benefits of the true arch but there's also shape issues that matter, though probably not relevant to the TL1/TL2 divide.
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Old 06-20-2019, 11:20 AM   #17
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Default Re: [Magic] Using Shape Earth and Earth to Stone in construction

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I've been thinking about the impact Shape Earth and Earth to Stone would have on a setting, and I'm realizing a great deal about the spells is left unclear. Many of the most important questions involve fusing things together. For example, can Shape Earth fuse to pieces of stone together? Or even transform a rubble pile into a single continuous block? Similarly, if you pack a hole in a wall with dirt, and cast Earth to Stone, will the resulting stone be chemically bonded to the wall, or will it at best form a tight plug?

If the answer to these questions is "yes", it could help explain how bronze age (or even stone age) civilizations are able to build massive temples that in some ways resemble gothic cathedrals more than anything historically accomplished at that tech level. But Magic is extremely vague on what exactly these spells do.
I always thought that someone using these spells in the Banestorm setting could have built a canal between the Major Rivers of Caithness. It would have both heated up the civil war and brought outsiders into the picture. Mainly because the canal would seriously strengthened the Kingdom.

Certainly these spells, and some knowledge of engineering, would allow the building of fine stable canals quickly. The money making options for a kingdom would be major.
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Old 06-20-2019, 11:50 AM   #18
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Default Re: [Magic] Using Shape Earth and Earth to Stone in construction

If you fuse all the stones, you don't necessarily get a true arch. You get a shape that could be described as post-and-lintel with a semicircle chopped out of the center bottom of the lintel. I'm not an engineer, but it's not obvious to me that an homogeneous block with a semicircular cutout is stronger than the full post-and-lintel (itself weak compared to an arch).

The point of the arch is converting the downward stress into stress along the perimeter of the arch, and thus making it compressive around the arch span rather than tensile at the bottom edge of the lintel. Qualitatively speaking, the wedge shapes of the arch stones (or the stones + their mortar) gradually change the downward stress into more transverse compression, starting with trying to drive the keystone down into the rest of the arch, the driving of which wedge becomes a stress forcing the two blocks to either side apart horizontally, and so on around the boundary of the arch. For another comparison, there's a shape called a "jack" arch, which isn't curved at all, but rather a horizontal series of wedge-shaped blocks or bricks slanted outward at the tops, with those wedges filling a flat horizontal shape, identical in outline to a lintel. If it were only the bottom edge of the shape that mattered and not the internal connections, then a jack arch wouldn't be any stronger than a lintel, but merely decorative at best, but structurally not worth the bother.

If the crystals in solid stone could do that redirection of the downward force on their own, then it seems post-and-lintel would have been a fine solution to start with -- though cutting out the middle reduces the load the lintel itself contributes, it also weakens the lintel by making in thinner where the most stress is. Maybe removing part the stone makes the forces go sideways just because they no longer have a choice (other than to go down "into the air" and break the stone). But maybe it's the more macroscopic geometry of those "voussior" wedges that make the real difference, rather than the crystalline structure of the minerals in the stone or molecular bonds, or just the curved outline of the span over the doorway.

I don't suppose anyone out there just happens to be a civil engineer or architect?
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Old 06-20-2019, 01:34 PM   #19
arnej
 
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Default Re: [Magic] Using Shape Earth and Earth to Stone in construction

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Even if shape earth and earth to stone can't form chunks that are attached to existing stone, you can do plenty with large shaped chunks of stone that aren't attached. to each other, just placed against one another.
I think this explains lots of Incan ruins that I saw in Peru. :)
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Old 06-20-2019, 01:53 PM   #20
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Default Re: [Magic] Using Shape Earth and Earth to Stone in construction

From my perspective. The Shape spell would allow you to form fairly intricate homes very quickly out of stone but building them so they don't fall apart would require Engineering-Civil and making them beautiful would require Artist-Sculptor.
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