cgal/Arrangement_on_surface_2/demo/earth/Triangles.cpp

81 lines
2.2 KiB
C++

// Copyright(c) 2023, 2024 Tel-Aviv University (Israel).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
// Author(s): Engin Deniz Diktas <denizdiktas@gmail.com>
#include "Triangles.h"
#include <iostream>
//! \brief
Triangles::Triangles(std::vector<QVector3D>& vertices) {
initializeOpenGLFunctions();
// computer the normals of each vertex
std::vector<QVector3D> normals;
for(const auto& p : vertices) {
auto n = p;
n.normalize();
normals.push_back(n);
}
int num_triangles = vertices.size() / 3;
// strided vertex-data
std::vector<QVector3D> vertex_data;
for (int i = 0; i < vertices.size(); ++i) {
vertex_data.push_back(vertices[i]);
vertex_data.push_back(normals[i]);
}
// DEFINE OPENGL BUFFERS
glGenVertexArrays(1, &m_vao);
glBindVertexArray(m_vao);
m_num_vertices = vertices.size();
// Vertex Buffer
glGenBuffers(1, &m_vbo);
glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
auto vertex_buffer_size = sizeof(QVector3D) * vertex_data.size();
auto vertex_buffer_data = reinterpret_cast<const void*>(vertex_data.data());
glBufferData(GL_ARRAY_BUFFER, vertex_buffer_size, vertex_buffer_data,
GL_STATIC_DRAW);
// Position Vertex-Attribute
GLint position_attrib_index = 0;
const void* position_offset = 0;
GLsizei stride = 6 * sizeof(float);
glVertexAttribPointer(position_attrib_index, 3, GL_FLOAT, GL_FALSE, stride,
position_offset);
glEnableVertexAttribArray(position_attrib_index);
// Normal Vertex-Attribute
GLint normal_attrib_index = 1;
auto* normal_offset = reinterpret_cast<const void*>(3 * sizeof(float));
glVertexAttribPointer(normal_attrib_index, 3, GL_FLOAT, GL_FALSE, stride,
normal_offset);
glEnableVertexAttribArray(normal_attrib_index);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
}
//! \brief
void Triangles::set_color(const QVector4D& rgba)
{ m_color = rgba; }
//! \brief
const QVector4D& Triangles::get_color() const { return m_color; }
//! \brief
void Triangles::draw() {
// DRAW TRIANGLES
glBindVertexArray(m_vao);
glDrawArrays(GL_TRIANGLES, 0, m_num_vertices);
glBindVertexArray(0);
}