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File:Duopyramid.png

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Summary

Description
English: Stereographic projection of 6-4 Duopyramid (blu) with its dual Duoprism (phantom red). In the last row, the Duopyramid is projected by a direction perpendicular to the first one; so the two parameters (6,4) seem to be reversed. Indeed, asymmetry is due to the projection: the two parameters are symmetric in 4D.
Date
Source Own work
Author Claudio Rocchini

Licensing

I, the copyright holder of this work, hereby publish it under the following license:
w:en:Creative Commons
attribution share alike
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Under the following conditions:
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  • share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.

Source Code

The source code needs some implementation of point3 and point4.

/* Duopyramid VRML generator
 * (C) 2012-2013 CC-By 3.0 Claudio Rocchini
 */
 
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "point3.h"
#include "point4.h"

const double PI = 3.1415926535897932384626433832795;
const double S = 100;
const double K1 = 0.03;
const double K2 = 0.06;
	
static void draw_sphere( FILE * fo, const point3 & p, double r ) {
	fprintf(fo,
		"Separator{\n"
		"\tTranslation { translation %g %g %g }\n"
		"\tSphere { radius %g }\n"
		"}\n"
		,p.x*S,p.y*S,p.z*S,r*S
	);
}
		
static void draw_edge( FILE * fo, const point3 & p1, double r1, const point3 & p2, double r2 ) {
	point3 d = p2-p1; double l = lenght(d); normalize(d);
	point3 c = (p1+p2)/2.0;
	point3 Y(0,1,0);
	point3 rd = d^Y; normalize(rd); double ra = -acos(d*Y);
	double r = (r1+r2)/2;
	
	fprintf(fo,
		"Separator{\n"
		"\tTranslation { translation %g %g %g }\n"
		"\t\tRotation { rotation %g %g %g %g }\n"
		"\t\tCylinder {\n\t\tparts SIDES\n"
        "\t\tradius %g\n\t\theight %g\n"
		"\t}\n}\n"
		,c.x*S,c.y*S,c.z*S
		,rd.x,rd.y,rd.z,ra
		,r*S,l*S
	);
}

void rotate( point4 & p ) {
	double theta = PI/2; double cs = cos(theta); double sn = sin(theta);
	double z = p.y;
	double v = p.v;
	p.y = z * cs - v * sn;
	p.v = z * sn + v * cs;
}

void proj( const point4 & v, point3 & w, double & R ) {
	w.x = v.x / (2-v.v); w.y = v.y / (2-v.v);
	w.z = v.z / (2-v.v); R = 1.0 / (2-v.v);
}

int main() {
	const int P = 6;
	const int Q = 4;
	int i,j;
	
	const int NV = P*Q; point4 V[NV];
	for(i=0;i<P;++i) {
		double ai = i*2*PI/P;
		for(j=0;j<Q;++j) {
			double aj = j*2*PI/Q;
			V[i*Q+j].x = cos(ai); V[i*Q+j].y = sin(ai);
			V[i*Q+j].z = cos(aj); V[i*Q+j].v = sin(aj);
		}
	}
	
	const int NV2 = P+Q; point4 V2[NV2];
	for(i=0;i<P;++i) {
		double a1 = i*2*PI/P;         double x1 = cos(a1); double y1 = sin(a1);
		double a2 = ((i+1)%P)*2*PI/P; double x2 = cos(a2); double y2 = sin(a2);
		V2[i+0].x = (x1+x2)/2; V2[i+0].z = 0;
		V2[i+0].y = (y1+y2)/2; V2[i+0].v = 0;
	}
	for(j=0;j<Q;++j) {
		double a1 = j*2*PI/Q;         double z1 = cos(a1); double v1 = sin(a1);
		double a2 = ((j+1)%Q)*2*PI/Q; double z2 = cos(a2); double v2 = sin(a2);
		V2[j+P].x = 0; V2[j+P].z = (z1+z2)/2;
		V2[j+P].y = 0; V2[j+P].v = (v1+v2)/2;
	}
	
	point3 VP[NV]; double R[NV];
	point3 VP2[NV2]; double R2[NV2];
	for(i=0;i<NV;++i) {
		rotate(V[i]); proj(V[i],VP[i],R[i]);
	}
	for(i=0;i<NV2;++i) {
		rotate(V2[i]); proj(V2[i],VP2[i],R2[i]);
	}

	FILE * fo = fopen("duppyramid.wrl","w");	
	fprintf(fo, "#VRML V1.0 ascii\n" );
	
	fprintf(fo,
		"Material {\n"
        "\tdiffuseColor [0.4 0.1 0.0]\n"
        "\tspecularColor [0.7 0.7 0.7]\n"
        "\temissiveColor[]\n"
        "\tambientColor[0.4 0.4 0.4]\n"
        "\tshininess 0.16\n"
        "\ttransparency 0.5\n"
		"}\n"
	);
 
	for(i=0;i<NV;++i)
		draw_sphere(fo,VP[i],R[i]*K2);
	for(j=0;j<Q;++j)
		for(i=0;i<P;++i) {
			draw_edge(fo,VP[i*Q+j],R[i*Q+j]*K1,VP[((i+1)%P)*Q+j],R[((i+1)%P)*Q+j]*K1);
			draw_edge(fo,VP[i*Q+j],R[i*Q+j]*K1,VP[i*Q+(j+1)%Q],R[i*Q+(j+1)%Q]*K1);
		}

	fprintf(fo,
		"Material {\n"
        "\tdiffuseColor [0.1 0.2 0.5]\n"
        "\tspecularColor [0.7 0.7 0.7]\n"
        "\temissiveColor[]\n"
        "\tambientColor[0.4 0.4 0.4]\n"
        "\tshininess 0.16\n"
        "\ttransparency 0.0\n"
		"}\n"
	);
 
	for(i=0;i<NV2;++i)
		draw_sphere(fo,VP2[i],R2[i]*K2);

	for(i=0;i<P;++i)
		draw_edge(fo,VP2[i],R2[i]*K1,VP2[(i+1)%P],R2[(i+1)%P]*K1);
	for(j=0;j<Q;++j)
		draw_edge(fo,VP2[P+j],R2[P+j]*K1,VP2[P+(j+1)%Q],R2[P+(j+1)%Q]*K1);
	for(i=0;i<P;++i)
	for(j=0;j<Q;++j)
		draw_edge(fo,VP2[0+i],R2[0+i]*K1,VP2[P+j],R2[P+j]*K1);

	fclose(fo);
	
	return 0;
}

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14 December 2012

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Date/TimeThumbnailDimensionsUserComment
current14:54, 14 December 2012Thumbnail for version as of 14:54, 14 December 20121,000 × 1,360 (972 KB)RocchiniUser created page with UploadWizard

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