I do have 3D array[250][150][250] which represents human body (basically it is a voxel object). Each element contain values from 0 to 255, where 255 means that an elements is empty and should be ignored and 0-254 represent different organs (like skin, lung and etch) hence should be drawn. In my program I writing the data of elements that should be drawn in 2 txt files (vertices.txt and indices.txt). vertices.txt contain x,y and z coordinates of all voxel vertices that should be drawn and indices.txt contain all indices.
I am able to render whole body with all organs that is not the problem.
Example from vertices.txt:
193 68 0 // coordinates of a voxel
193 68 1
193 69 0
193 69 1
Example from indices.txt:
4 5 7 4 6 7 // face of a voxel. Each face is represented by 2 triangles. Hence, we need 6 indices.
2 3 7 2 6 7
0 4 6 0 2 6
My problem is that I do not know how to render a specific part of a body (For example: lets say that I want to render only lungs). How can I do that? Do I have to create indices.txt and vetices.txt for each individual organ (basically making each organ as a separate mesh)?
EDIT: Code that is responsible for writing into vertices.txt and indices.txt.
void writePhantomDataToThefile(std::ofstream& verticies_out_file, std::ofstream& indicies_out_file)
{
verticies_out_file.open(vertices, std::ofstream::out | std::ofstream::trunc);
indicies_out_file.open(indices, std::ofstream::out | std::ofstream::trunc);
unsigned elements = 0;
for (int z = 0; z < zMax; z++)
{
for (int y = 0; y < yMax; y++)
{
for (int x = 0; x < xMax; x++)
{
if (phantom->voxel[x][y][z] == emptyVoxel) // empty voxel is 255
{
continue;
}
else
{
if ((x != 0 && x != (xMax - 1)) && (y != 0 && y != (yMax - 1)) && (z != 0 && z != (zMax - 1)) &&
(phantom->voxel[x + 1][y][z] != emptyVoxel) && (phantom->voxel[x - 1][y][z] != emptyVoxel) && (phantom->voxel[x][y + 1][z] != emptyVoxel) &&
(phantom->voxel[x][y - 1][z] != emptyVoxel) && (phantom->voxel[x][y][z + 1] != emptyVoxel) && (phantom->voxel[x][y][z - 1] != emptyVoxel))
{ // this part of code skips elements if is surrounded by elements != 255
continue; // basically right now I am drawing the skin of a body
}
verticies_out_file << x << " " << y << " " << z << std::endl;
verticies_out_file << x << " " << y << " " << z + 1 << std::endl;
verticies_out_file << x << " " << y + 1 << " " << z << std::endl;
verticies_out_file << x << " " << y + 1 << " " << z + 1 << std::endl;
verticies_out_file << x + 1 << " " << y << " " << z << std::endl;
verticies_out_file << x + 1 << " " << y << " " << z + 1 << std::endl;
verticies_out_file << x + 1 << " " << y + 1 << " " << z << std::endl;
verticies_out_file << x + 1 << " " << y + 1 << " " << z + 1 << std::endl;
if (x != 0 && x != (xMax - 1))
{
if (phantom->voxel[x - 1][y][z] != emptyVoxel)
{
indicies_out_file << (elements * 8) << " " << (elements * 8 + 2) << " " << (elements * 8 + 3) << " "
<< (elements * 8) << " " << (elements * 8 + 1) << " "<< (elements * 8 + 3) << std::endl; // left face
}
if (phantom->voxel[x + 1][y][z] != emptyVoxel)
{
indicies_out_file << (elements * 8 + 4) << " " << (elements * 8 + 5) << " "<< (elements * 8 + 7) << " "
<< (elements * 8 + 4) << " "<< (elements * 8 + 6) << " " << (elements * 8 + 7) << std::endl; // right face
}
}
else
{
if (x == 0)
{
indicies_out_file << (elements * 8) << " " << (elements * 8 + 2) << " "<< (elements * 8 + 3) << " "
<< (elements * 8) << " "<< (elements * 8 + 1) << " "<< (elements * 8 + 3) << std::endl; // left face
}
if (x == (xMax - 1))
{
indicies_out_file << (elements * 8 + 4) << " "<< (elements * 8 + 5) << " "<< (elements * 8 + 7) << " "
<< (elements * 8 + 4) << " " << (elements * 8 + 6) << " " << (elements * 8 + 7) << std::endl; // right face
}
}
if (y != 0 && y != (yMax - 1))
{
if (phantom->voxel[x][y - 1][z] != emptyVoxel)
{
indicies_out_file << (elements * 8 + 1) << " " << (elements * 8 + 5) << " "<< (elements * 8 + 4) << " "
<< (elements * 8 + 1) << " " << (elements * 8) << " "<< (elements * 8 + 4) << std::endl; // bottom face
}
if (phantom->voxel[x][y + 1][z] != emptyVoxel)
{
indicies_out_file << (elements * 8 + 2) << " " << (elements * 8 + 3) << " " << (elements * 8 + 7) << " "
<< (elements * 8 + 2) << " " << (elements * 8 + 6) << " " << (elements * 8 + 7) << std::endl; // top face
}
}
else
{
if (y == 0)
{
indicies_out_file << (elements * 8 + 1) << " " << (elements * 8 + 5) << " " << (elements * 8 + 4) << " "
<< (elements * 8 + 1) << " " << (elements * 8) << " " << (elements * 8 + 4) << std::endl; // bottom face
}
if (y == (yMax - 1))
{
indicies_out_file << (elements * 8 + 2) << " " << (elements * 8 + 3) << " " << (elements * 8 + 7) << " "
<< (elements * 8 + 2) << " " << (elements * 8 + 6) << " " << (elements * 8 + 7) << std::endl; // top face
}
}
if (z != 0 && z != (zMax - 1))
{
if (phantom->voxel[x][y][z - 1] != emptyVoxel)
{
indicies_out_file << (elements * 8) << " " << (elements * 8 + 4) << " " << (elements * 8 + 6) << " "
<< (elements * 8) << " " << (elements * 8 + 2) << " " << (elements * 8 + 6) << std::endl; // front face
}
if (phantom->voxel[x][y][z + 1] != emptyVoxel)
{
indicies_out_file << (elements * 8 + 1) << " " << (elements * 8 + 5) << " " << (elements * 8 + 7) << " "
<< (elements * 8 + 1) << " " << (elements * 8 + 3) << " " << (elements * 8 + 7) << std::endl; // back face
}
}
else
{
if (z == 0)
{
indicies_out_file << (elements * 8) << " " << (elements * 8 + 4) << " " << (elements * 8 + 6) << " "
<< (elements * 8) << " " << (elements * 8 + 2) << " " << (elements * 8 + 6) << std::endl; // front face
}
if (z == (zMax - 1))
{
indicies_out_file << (elements * 8 + 1) << " " << (elements * 8 + 5) << " " << (elements * 8 + 7) << " "
<< (elements * 8 + 1) << " " << (elements * 8 + 3) << " " << (elements * 8 + 7) << std::endl; // back face
}
}
elements++;
}
}
}
}
verticies_out_file.close();
indicies_out_file.close();
}
Mesh.cpp
#include "Mesh.h"
#include <iostream>
#include <sstream>
#include <fstream>
Mesh::Mesh()
{
loaded = false;
}
Mesh::~Mesh()
{
glDeleteVertexArrays(1, &vao);
glDeleteBuffers(1, &vbo);
glDeleteBuffers(1, &ibo);
}
void Mesh::loadVertices(std::string fileName)
{
int item = 0, n = 0, x = 0, y = 0;
std::ifstream is(fileName, std::ifstream::binary);
if (is) {
is.seekg(0, is.end);
int length = is.tellg();
is.seekg(0, is.beg);
char* buffer = new char[length];
is.read(buffer, length);
is.close();
for (unsigned int i = 0; i < is.gcount(); i++)
{
switch (buffer[i])
{
case '\r':
break;
case '\n':
{
vertices.push_back(glm::vec3(y, item, x));
n = 0;
item = 0;
break;
}
case ' ':
{
n++;
if (n == 1)
{
x = item;
}
else
{
y = item;
}
item = 0;
break;
}
case '0': case '1': case '2': case '3':
case '4': case '5': case '6': case '7':
case '8': case '9':
item = 10 * item + buffer[i] - '0';
break;
default:
std::cerr << "Bad format\n";
}
}
delete[] buffer;
}
}
void Mesh::loadIndices(std::string fileName)
{
int item = 0;
std::ifstream is(fileName, std::ifstream::binary);
if (is) {
is.seekg(0, is.end);
int length = is.tellg();
is.seekg(0, is.beg);
char* buffer = new char[length];
is.read(buffer, length);
is.close();
for (unsigned int i = 0; i < is.gcount(); i++)
{
switch (buffer[i])
{
case '\r':
break;
case '\n':
{
indicies.push_back(item);
item = 0;
break;
}
case ' ':
{
indicies.push_back(item);
item = 0;
break;
}
case '0': case '1': case '2': case '3':
case '4': case '5': case '6': case '7':
case '8': case '9':
item = 10 * item + buffer[i] - '0';
break;
default:
std::cerr << "Bad format\n";
}
}
delete[] buffer;
}
}
bool Mesh::loadOBJ()
{
loadVertices("Phantom Data/FA_vertices.txt");
loadIndices("Phantom Data/FA_indices.txt");
initBuffers();
return (loaded = true);
}
void Mesh::draw()
{
if (!loaded) return;
glBindVertexArray(vao);
glDrawElements(GL_TRIANGLES, indicies.size(), GL_UNSIGNED_INT, nullptr);
glBindVertexArray(0);
}
void Mesh::initBuffers()
{
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(glm::vec3), &vertices[0], GL_STATIC_DRAW);
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(glm::vec3), NULL);
glEnableVertexAttribArray(0);
glGenBuffers(1, &ibo);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indicies.size() * sizeof(GLuint), &indicies[0], GL_STATIC_DRAW);
glBindVertexArray(0);
}