109 lines
3.1 KiB
C++
109 lines
3.1 KiB
C++
#include "sphere.h"
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#define M_PI 3.14159265358979323846
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#define MAGIC_RATIO 0.37139f
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Sphere::Sphere(int n)
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{
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// icosahedron :
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// top cap
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createVertex(0, 1);
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for(int i=0; i<5; i++)
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createVertex(i/5.f, 1-MAGIC_RATIO);
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// bottom cap
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createVertex(0, 0);
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for(int i=0; i<5; i++)
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createVertex((i+0.5f)/5.f, MAGIC_RATIO);
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// Compute faces
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for(int i=0; i<5; i++){
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int top = 1;
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int bottom = 7;
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int offset = (i+1)%5;
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// top cap
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addFace(0, top+i, top+offset);
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// bottom cap
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addFace(6, bottom+offset, bottom+i);
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// middle ribbon
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addFace(top+i, bottom+i, top+offset);
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addFace(top+offset, bottom+i, bottom+offset);
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}
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// geodesic subdivisions :
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for(int i=0; i<n; i++){
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edges = new Edge[vertices.size()-1];
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int nb_triangles = indices.size()/3;
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for(int j=0; j<nb_triangles; j++)
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{
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int vid[3];
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for(int k=0; k<3; k++)
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{
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int idA = indices[j*3 + k];
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int idB = indices[j*3 + (k+1)%3];
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int a = idA < idB ? idA : idB;
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int b = idA > idB ? idA : idB;
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vid[k] = getEdge(a, b);
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}
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for(int k=0; k<3; k++)
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addFace(indices[j*3 + k], vid[k], vid[(k+2)%3]);
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addFace(vid[0], vid[1], vid[2]);
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}
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delete[](edges);
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indices.erase(indices.begin(), indices.begin()+nb_triangles*3);
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}
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}
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int Sphere::getEdge(int a, int b)
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{
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Edge* current = edges+a;
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int vid = -1;
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while(vid == -1)
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{
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if(current->b == b)
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vid = current->vertex;
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else if(current->next == NULL)
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{
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// creating subdivision vertex
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Vertex v;
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Vertex v0 = vertices[a];
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Vertex v1 = vertices[b];
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v.position = glm::normalize((v0.position + v1.position)/2.f);
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v.normal = v.position;
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// u/v sphériques, cohérents sur toute la sphère sauf des artefacts au niveau des u==0
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float newU = (v.position.x < 0 ? 1.5f : 1.f) + atan(v.position.z/v.position.x)/(2*M_PI);
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float newV = acos(v.position.y)/M_PI;
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v.texCoord = glm::vec2(newU - floor(newU), newV);
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// alternative, u/v moyennés :
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//v.texCoord = (v0.texCoord + v1.texCoord)/2.f;
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vid = vertices.size();
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addVertex(v);
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// inserting the new vertex in the edge collection
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if(current->b == -1)
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{
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current->vertex = vid;
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current->b = b;
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}
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else
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current->next = new Edge(b, vid);
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}
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else
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current = current->next;
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}
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return vid;
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}
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void Sphere::createVertex(float u, float v)
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{
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Vertex vert;
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vert.position = glm::vec3(cos(u*2*M_PI)*sin(v*M_PI),
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cos(v*M_PI),
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sin(u*2*M_PI)*sin(v*M_PI));
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vert.normal = vert.position;
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vert.texCoord = glm::vec2(u, v);
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addVertex(vert);
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}
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