+#define _USE_MATH_DEFINES
#include <cmath>
+#include <vector>
#include "primitivebuilder.h"
#include "sphere.h"
+using namespace std;
+
namespace Msp {
namespace GL {
}
}
+
+// https://en.wikipedia.org/wiki/Regular_icosahedron#Cartesian_coordinates
+float IcoSphereBuilder::base_vertices[12*3] =
+{
+ 0.0f, -0.5257311f, -0.8506508f,
+ 0.0f, 0.5257311f, -0.8506508f,
+ 0.0f, -0.5257311f, 0.8506508f,
+ 0.0f, 0.5257311f, 0.8506508f,
+ -0.8506508f, 0.0f, -0.5257311f,
+ -0.8506508f, 0.0f, 0.5257311f,
+ 0.8506508f, 0.0f, -0.5257311f,
+ 0.8506508f, 0.0f, 0.5257311f,
+ -0.5257311f, -0.8506508f, 0.0f,
+ 0.5257311f, -0.8506508f, 0.0f,
+ -0.5257311f, 0.8506508f, 0.0f,
+ 0.5257311f, 0.8506508f, 0.0f
+};
+
+unsigned IcoSphereBuilder::base_triangles[20*3] =
+{
+ 0, 1, 6,
+ 1, 0, 4,
+ 2, 3, 5,
+ 3, 2, 7,
+ 4, 5, 10,
+ 5, 4, 8,
+ 6, 7, 9,
+ 7, 6, 11,
+ 8, 9, 2,
+ 9, 8, 0,
+ 10, 11, 1,
+ 11, 10, 3,
+ 0, 8, 4,
+ 0, 6, 9,
+ 1, 4, 10,
+ 1, 11, 6,
+ 2, 5, 8,
+ 2, 9, 7,
+ 3, 10, 5,
+ 3, 7, 11
+};
+
+unsigned IcoSphereBuilder::base_edges[30*2] = { 0, 0 };
+unsigned IcoSphereBuilder::base_tri_edges[20*3] = { 0, 0, 0 };
+
+IcoSphereBuilder::IcoSphereBuilder(float r, unsigned s):
+ radius(r),
+ subdivision(s)
+{
+ if(base_edges[0]==base_edges[1])
+ initialize_edges();
+}
+
+void IcoSphereBuilder::initialize_edges()
+{
+ vector<int> edge_map(12*12, -1);
+ unsigned next_edge = 0;
+ for(unsigned i=0; i<20; ++i)
+ for(unsigned j=0; j<3; ++j)
+ {
+ unsigned v1 = base_triangles[i*3+j];
+ unsigned v2 = base_triangles[i*3+(j+1)%3];
+ int e = edge_map[v1*12+v2];
+ if(e<0)
+ {
+ e = next_edge++;
+ base_edges[e*2] = v1;
+ base_edges[e*2+1] = v2;
+ // The other triangle using this edge will have the vertices swapped
+ edge_map[v2*12+v1] = e|32;
+ }
+ base_tri_edges[i*3+j] = e;
+ }
+}
+
+void IcoSphereBuilder::build(PrimitiveBuilder &bld) const
+{
+ for(unsigned i=0; i<12; ++i)
+ {
+ const float *v = base_vertices+i*3;
+ bld.normal(v[0], v[1], v[2]);
+ bld.vertex(v[0]*radius, v[1]*radius, v[2]*radius);
+ }
+
+ if(subdivision>1)
+ {
+ vector<Vector3> edge_subdiv(30*(subdivision+1));
+ for(unsigned i=0; i<30; ++i)
+ {
+ Vector3 v1(base_vertices+base_edges[i*2]*3);
+ Vector3 v2(base_vertices+base_edges[i*2+1]*3);
+ for(unsigned j=1; j<subdivision; ++j)
+ {
+ float t = static_cast<float>(j)/subdivision;
+ Vector3 v = v1*(1.0f-t)+v2*t;
+ edge_subdiv[i*(subdivision-1)+j-1] = v;
+ v.normalize();
+ bld.normal(v);
+ bld.vertex(v*radius);
+ }
+ }
+
+ for(unsigned i=0; i<20; ++i)
+ for(unsigned j=1; j<subdivision; ++j)
+ {
+ unsigned e = base_tri_edges[i*3];
+ Vector3 v1 = edge_subdiv[edge_vertex(e, subdivision-j)];
+ e = base_tri_edges[i*3+1];
+ Vector3 v2 = edge_subdiv[edge_vertex(e, j)];
+ for(unsigned k=1; k<j; ++k)
+ {
+ float t = static_cast<float>(k)/j;
+ Vector3 v = normalize(v1*(1.0f-t)+v2*t);
+ bld.normal(v);
+ bld.vertex(v*radius);
+ }
+ }
+
+ for(unsigned i=0; i<20; ++i)
+ {
+ unsigned mid = 12+30*(subdivision-1)+i*(subdivision-1)*(subdivision-2)/2;
+ for(unsigned j=1; j<=subdivision; ++j)
+ {
+ bld.begin(TRIANGLE_STRIP);
+ if(j==subdivision)
+ bld.element(base_triangles[i*3]);
+ else
+ bld.element(12+edge_vertex(base_tri_edges[i*3], subdivision-j));
+
+ if(j==1)
+ {
+ bld.element(base_triangles[i*3+1]);
+ bld.element(12+edge_vertex(base_tri_edges[i*3+1], j));
+ }
+ else
+ {
+ bld.element(12+edge_vertex(base_tri_edges[i*3], subdivision-j+1));
+
+ if(j==subdivision)
+ bld.element(12+edge_vertex(base_tri_edges[i*3+2], subdivision-1));
+ else
+ bld.element(mid+(j-1)*(j-2)/2);
+
+ for(unsigned k=2; k<j; ++k)
+ {
+ bld.element(mid+(j-2)*(j-3)/2+k-2);
+ if(j==subdivision)
+ bld.element(12+edge_vertex(base_tri_edges[i*3+2], subdivision-k));
+ else
+ bld.element(mid+(j-1)*(j-2)/2+k-1);
+ }
+
+ bld.element(12+edge_vertex(base_tri_edges[i*3+1], j-1));
+ if(j==subdivision)
+ bld.element(base_triangles[i*3+2]);
+ else
+ bld.element(12+edge_vertex(base_tri_edges[i*3+1], j));
+ }
+ bld.end();
+ }
+ }
+ }
+ else
+ {
+ bld.begin(TRIANGLES);
+ for(unsigned i=0; i<20*3; ++i)
+ bld.element(base_triangles[i]);
+ bld.end();
+ }
+}
+
+unsigned IcoSphereBuilder::edge_vertex(unsigned e, unsigned i) const
+{
+ return (e&31)*(subdivision-1)+((e&32)?subdivision-i:i)-1;
+}
+
} // namespace GL
} // namespace Msp
projects / libs / gl.git / blobdiff