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29 Apr 2024 15:50:03 EDT (-0400)
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From: Bald Eagle
Subject: Geometric task library?
Date: 3 Aug 2014 17:40:00
Message: <web.53deac1d250d318b5e7df57c0@news.povray.org>
Does anyone know of a source for existing code or macros for performing
geometric tasks that are likely to crop up while modeling things in 3d?

Circumscribing a circle around a triangle, finding the center of a sphere that
includes that circle in its surface, finding a circle that is tangent to 3 other
circles, etc.

No doubt, I could code a few such algebraic solutions to geometric problems, but
why reinvent the wheel, and there might be methods out there that use POV-Ray's
bounding boxes and other features to speed up the process...

Thanks!


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From: FractRacer
Subject: Re: Geometric task library?
Date: 4 Aug 2014 03:05:19
Message: <53df30af@news.povray.org>

>
> Does anyone know of a source for existing code or macros for performing
> geometric tasks that are likely to crop up while modeling things in 3d?
>
> Circumscribing a circle around a triangle, finding the center of a sphere that
> includes that circle in its surface, finding a circle that is tangent to 3 other
> circles, etc.
>
> No doubt, I could code a few such algebraic solutions to geometric problems, but
> why reinvent the wheel, and there might be methods out there that use POV-Ray's
> bounding boxes and other features to speed up the process...
>
> Thanks!
>
>
  Take a look at the page of Friedrich A. Lohmueller, he wrote an 
analytical_g.inc file (macros for Analytical Geometry)
http://wwww.f-lohmueller.de


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From: Bald Eagle
Subject: Re: Geometric task library?
Date: 4 Aug 2014 14:25:00
Message: <web.53dfcfe1401cb4475e7df57c0@news.povray.org>
Thanks - I found that, and indeed it has some good stuff in there.

Some of it's a bit cryptic, but I'm working through it.

It's a bit rough going.

It can be challenging to keep the syntax, math, geometry, and POV-Ray's
interpretation of a "Vector" all straight.

Still working on the sphere in contact with the 3 points of a triangle and a 4th
point...  Can't seem to get it to work out.


#declare Corner_A_1 = <0, 0, 0>;
#declare Corner_A_2 = <4, 0, 0>;
#declare Corner_A_3 = <4, 4, 0>;
#declare H = 1;


#declare Circumscribed = object {Circumscribe (Corner_A_1, Corner_A_2,
Corner_A_3)};



 #macro Circumscribed_Sphere (Corner_1, Corner_2, Corner_3, Height)  // POINTS
A, B, C
 union{
  #declare Middle =  Triangle_M_out (Corner_1, Corner_2, Corner_3); // POINT P /
Middle
   #declare Radius =  Triangle_R_out (Corner_1, Corner_2, Corner_3); //
   #declare Normal =  Triangle_Normal(Corner_1, Corner_2, Corner_3);

   sphere {Middle, 0.1 translate Normal texture {Plane} }
   object {Vector (Middle, vtransform ( Middle, transform {translate Normal} ),
0.05) texture {Plane}}
   object {Vector (Middle, vtransform ( Middle, transform {translate -4*Normal}
), 0.05) texture {Plane}}

   // translate Middle along Normal by Height to get point D
   #declare PointD  =  vtransform ( Middle, transform {translate Normal*Height}
) ;
   sphere {o, 0.1 translate PointD texture {Object} }   // POINT D
   sphere {Corner_A_3, 0.1  texture {Object} }
   object {Vector (Corner_A_3, PointD, 0.05) texture {Tex_Dark}}


   // midpoint EP
   #declare Midpoint = (Corner_A_3 + PointD)/2;
   sphere {Midpoint, 0.1  texture {Object} }
   #declare Tangent = Triangle_Normal ( Corner_A_3, Middle, PointD );
   // Perpendicular to triangle containing sphere center
   #declare PerpRef = vtransform (Tangent*5, transform {translate Corner_A_3} );
// Just a big tangent
   object {Vector (Corner_A_3, PerpRef, 0.05) texture {Plane}}


   #declare Perp = vcross (PointD-Corner_A_3, Tangent);
   #declare PerpN = vnormalize (Perp);
   #declare PerpV = vtransform (Perp*2, transform {translate Midpoint} );
   object {Vector (Midpoint, PerpV, 0.05) texture {Tex_Dark}}
   #declare Adjacent = vlength (Midpoint - PointD);
   #declare Theta = VAngleD (Midpoint - PointD, Middle - PointD);
   #declare Opposite = Adjacent * atan (Theta);


   #declare Center = vtransform (Midpoint, transform {translate PerpN *
Opposite} );
   sphere {Center, 0.1  texture {Object} }
   #declare SRadius = vlength (Center - PointD);

   sphere {Center, SRadius texture {Shaded} } // Circumscribed sphere
   }
 #end

#declare  Sphere = object {Circumscribed_Sphere (Corner_A_1, Corner_A_2,
Corner_A_3, H)};


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From: FractRacer
Subject: Re: Geometric task library?
Date: 6 Aug 2014 08:48:40
Message: <53e22428@news.povray.org>
Here a version sligthly modified, the circle (draw by a torus) is in 
contact with the 3 points of the triangle.

#declare Corner_A_1 = <0, 0, 0>;
#declare Corner_A_2 = <4, 0, 0>;
#declare Corner_A_3 = <4, 4, 0>;
#declare H = 1;

#local AT = text {
ttf "arial.ttf", "A", 0.02, 0.0 // thickness, offset
pigment{ color rgb<1,1,1>*0.5 }
}


#local BT = text {
ttf "arial.ttf", "B", 0.02, 0.0 // thickness, offset
pigment{ color rgb<1,1,1>*0.5 }
}

#local CT = text {
ttf "arial.ttf", "C", 0.02, 0.0 // thickness, offset
pigment{ color rgb<1,1,1>*0.5 }
}


#local DT = text {
ttf "arial.ttf", "d", 0.02, 0.0 // thickness, offset
pigment{ color rgb<1,0.5,0.5> }
scale 0.75
}

#local MT = text {
ttf "arial.ttf", "m", 0.02, 0.0 // thickness, offset
pigment{ color rgb<1,0.5,0.5> }
scale 0.75
}


#local Plane = texture {
pigment {color rgb 0.7}
}

#local Object = texture {
pigment {color rgb <0.7,0.3,0.1>}
}

#local Tex_Dark = texture {
pigment {color rgb <0.17,0.13,0.81>}
}

#local Shaded   = texture {
pigment {color rgb <0.2,0.2,0.2> filter 0.87}
}


#local Rayon = 0.125;

#macro Circumscribed_Sphere (Corner_1, Corner_2, Corner_3, Height)

union{
cylinder {Corner_A_1-0.15*z, Corner_A_1+0.1*z, Rayon  texture {Object} }
object {AT translate Corner_A_1-x*1-y*0.5}
cylinder {Corner_A_2-0.15*z, Corner_A_2+0.1*z, Rayon  texture {Object} }
object {BT translate Corner_A_2+x*0.5-y*0.5}
cylinder {Corner_A_3-0.15*z, Corner_A_3+0.1*z, Rayon  texture {Object} }
object {CT translate Corner_A_3+x*0.5+y*0.5}

// POINT P / Middle
#declare Middle =  Triangle_M_out (Corner_A_1, Corner_A_2, Corner_A_3);
#declare Radius =  Triangle_R_out (Corner_A_1, Corner_A_2, Corner_A_3); /
/
#declare Normal =  Triangle_Normal(Corner_A_1, Corner_A_2, Corner_A_3);
#local TMC = Triangle_Mass_Center(Corner_A_1, Corner_A_2, Corner_A_3);

cylinder {
	Middle-0.15*z, Middle+0.25*z, Rayon  translate Normal
	texture {Shaded}
}
object {MT translate Middle-x*0.5}
cylinder {
	TMC-0.15*z , TMC +0.1*z, Rayon
	translate Normal
	texture {Tex_Dark}
}

#declare PointD  =  vtransform (
	Middle, transform {translate Normal*Height}
);

//		object {DT translate PointD}
object {
	Distance_Marker(Corner_A_3, PointD, 0.025)
	pigment {color rgb <1,1,0>}
}

object {
	Distance_Marker(Corner_A_3, Corner_A_2, 0.025)
	pigment {color rgb <1,1,1>}
}

object {
	Distance_Marker(Corner_A_3, Corner_A_1, 0.025)
	pigment {color rgb <1,1,1>}
}

object {
	Distance_Marker(Corner_A_2, Corner_A_1, 0.025)
	pigment {color rgb <1,1,1>}
}

object {
	Distance_Marker(PointD, Corner_A_2, 0.025)
	pigment {color rgb <1,1,0>}
}

#declare Midpoint = (Corner_A_3 + PointD)/2;
cylinder {
	Midpoint-0.15*z, Midpoint+0.0*z, Rayon/2
	pigment {color rgb <2,0,0>}
}

#declare Tangent = Triangle_Normal ( Corner_A_3, Middle, PointD );

//#declare PerpRef = vtransform (Tangent*5, transform {translate 
Corner_A_3} );
//		object {
//			Distance_Marker(Corner_A_3, PerpRef, 0.025)
//			texture {Plane}
//		}


#declare Perp = vcross (PointD-Corner_A_3, Tangent);
#declare PerpN = vnormalize (Perp);
#declare PerpV = vtransform (Perp*2, transform {translate Midpoint} );

#declare Adjacent = vlength (Midpoint - PointD);
#declare Theta = VAngleD (Midpoint - PointD, Middle - PointD);
#declare Opposite = Adjacent * atan (Theta);

#declare Center = vtransform (Midpoint, transform {translate PerpN * 
Opposite} );

#declare SRayon = vlength (Center - PointD);

torus {
	SRayon,0.01
	rotate x*90
	translate Middle
	pigment {color rgb <1,0.0,0.0>}
}
}
#end


#declare  Sphere = object {
	Circumscribed_Sphere (Corner_A_1, Corner_A_2,Corner_A_3, H)
};

Sphere

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---

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From: Bald Eagle
Subject: Re: Geometric task library?
Date: 6 Aug 2014 12:45:01
Message: <web.53e25a86401cb4475e7df57c0@news.povray.org>
I took a look at that.
Thanks a lot for looking through that for me.

See:
http://news.povray.org/povray.binaries.images/thread/<web.53e25769ad990c965e7df57c0%40news.povray.org>/


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