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#include "Icosahedron.h"
#include <iterator>
#include <algorithm>
#include <glbinding/gl/enum.h>
#include <glbinding/gl/functions.h>
#include <glm/glm.hpp>
#include <globjects/VertexArray.h>
#include <globjects/VertexAttributeBinding.h>
#include <globjects/Buffer.h>
using namespace gl;
using namespace glm;
using namespace globjects;
const std::array<vec3, 12> Icosahedron::vertices()
{
static const float t = (1.f + sqrtf(5.f)) * 0.5f; // 2.118
static const float i = inversesqrt(t * t + 1.f); // 0.427
static const float a = t * i; // 0.904
// icosahedron vertices (normalized) form three orthogonal golden rectangles
// http://en.wikipedia.org/wiki/Icosahedron#Cartesian_coordinates
return std::array<vec3, 12>{{
vec3(-i, a, 0)
, vec3( i, a, 0)
, vec3(-i,-a, 0)
, vec3( i,-a, 0)
, vec3( 0,-i, a)
, vec3( 0, i, a)
, vec3( 0,-i,-a)
, vec3( 0, i,-a)
, vec3( a, 0,-i)
, vec3( a, 0, i)
, vec3(-a, 0,-i)
, vec3(-a, 0, i)
}};
}
const std::array<Icosahedron::Face, 20> Icosahedron::indices()
{
return std::array<Face, 20>{{
Face{{ 0, 11, 5 }}
, Face{{ 0, 5, 1 }}
, Face{{ 0, 1, 7 }}
, Face{{ 0, 7, 10 }}
, Face{{ 0, 10, 11 }}
, Face{{ 1, 5, 9 }}
, Face{{ 5, 11, 4 }}
, Face{{ 11, 10, 2 }}
, Face{{ 10, 7, 6 }}
, Face{{ 7, 1, 8 }}
, Face{{ 3, 9, 4 }}
, Face{{ 3, 4, 2 }}
, Face{{ 3, 2, 6 }}
, Face{{ 3, 6, 8 }}
, Face{{ 3, 8, 9 }}
, Face{{ 4, 9, 5 }}
, Face{{ 2, 4, 11 }}
, Face{{ 6, 2, 10 }}
, Face{{ 8, 6, 7 }}
, Face{{ 9, 8, 1 }}
}};
}
Icosahedron::Icosahedron(const GLsizei iterations, const GLint positionLocation, const GLint normalLocation)
: m_vao(new VertexArray)
, m_vertices(new Buffer)
, m_indices(new Buffer)
{
auto v(vertices());
auto i(indices());
std::vector<vec3> vertices(v.begin(), v.end());
std::vector<Face> indices(i.begin(), i.end());
refine(vertices, indices, static_cast<char>(clamp(iterations, 0, 8)));
m_indices->setData(indices, GL_STATIC_DRAW);
m_vertices->setData(vertices, GL_STATIC_DRAW);
m_size = static_cast<GLsizei>(indices.size() * 3);
m_vao->bind();
m_indices->bind(GL_ELEMENT_ARRAY_BUFFER);
if (positionLocation >= 0)
{
auto vertexBinding = m_vao->binding(0);
vertexBinding->setAttribute(positionLocation);
vertexBinding->setBuffer(m_vertices, 0, sizeof(vec3));
vertexBinding->setFormat(3, GL_FLOAT, GL_TRUE);
m_vao->enable(0);
}
if (normalLocation >= 0)
{
auto vertexBinding = m_vao->binding(1);
vertexBinding->setAttribute(normalLocation);
vertexBinding->setBuffer(m_vertices, 0, sizeof(vec3));
vertexBinding->setFormat(3, GL_FLOAT, GL_TRUE);
m_vao->enable(1);
}
m_vao->unbind();
}
Icosahedron::~Icosahedron()
{
}
void Icosahedron::draw()
{
draw(GL_TRIANGLES);
}
void Icosahedron::draw(const GLenum mode)
{
glEnable(GL_DEPTH_TEST);
m_vao->bind();
m_vao->drawElements(mode, m_size, GL_UNSIGNED_SHORT, nullptr);
m_vao->unbind();
m_indices->unbind(GL_ELEMENT_ARRAY_BUFFER);
// glDisable(GL_DEPTH_TEST); // TODO: Use stackable states
}
void Icosahedron::refine(
std::vector<vec3> & vertices
, std::vector<Face> & indices
, const unsigned char levels)
{
std::unordered_map<uint, GLushort> cache;
for(int i = 0; i < levels; ++i)
{
const int size(static_cast<int>(indices.size()));
for(int f = 0; f < size; ++f)
{
Face & face = indices[f];
const GLushort a(face[0]);
const GLushort b(face[1]);
const GLushort c(face[2]);
const GLushort ab(split(a, b, vertices, cache));
const GLushort bc(split(b, c, vertices, cache));
const GLushort ca(split(c, a, vertices, cache));
face = {{ ab, bc, ca }};
indices.emplace_back(Face{{ a, ab, ca }});
indices.emplace_back(Face{{ b, bc, ab }});
indices.emplace_back(Face{{ c, ca, bc }});
}
}
}
GLushort Icosahedron::split(
const GLushort a
, const GLushort b
, std::vector<vec3> & points
, std::unordered_map<uint, GLushort> & cache)
{
const bool aSmaller(a < b);
const uint smaller(aSmaller ? a : b);
const uint greater(aSmaller ? b : a);
const uint hash((smaller << 16) + greater);
auto h(cache.find(hash));
if(cache.end() != h)
return h->second;
points.push_back(normalize((points[a] + points[b]) * .5f));
const GLushort i = static_cast<GLushort>(points.size() - 1);
cache[hash] = i;
return i;
}
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