tree.cpp

#include "tree.hpp"
#include <math.h>
using namespace cgp;


mesh create_cylinder_mesh(float radius, float height)
{
    mesh m; 
    int n = 1000;
    for (int i = 0; i < n; i++) {
        m.position.push_back(vec3{ cos(2 * Pi * i / n) * radius, sin(2 * Pi * i / n) * radius, (i % 2) * height- 0.05f * ((i+1) % 2) });
    }
    for (int i = 0; i < n; i++) {
        if (i % 2 == 0) m.connectivity.push_back(uint3{ i, (i+2)%n, (i + 1) % n });
        else m.connectivity.push_back(uint3{i, (i + 1) % n, (i+2)%n});
    }

    // To do: fill this mesh ...
    // ...
    // To add a position: 
    //   m.position.push_back(vec3{x,y,z})
    // Or in pre-allocating the buffer:
    //   m.position.resize(maximalSize);
    //   m.position[index] = vec3{x,y,z}; (with 0<= index < maximalSize)
    // 
    // Similar with the triangle connectivity:
    //  m.connectivity.push_back(uint3{index_1, index_2, index_3});


    // Need to call fill_empty_field() before returning the mesh 
    //  this function fill all empty buffer with default values (ex. normals, colors, etc).
    m.fill_empty_field();

    return m;
}

mesh create_cone_mesh(float radius, float height, float z_offset)
{
    mesh m; 
    int n = 10;
    for (int i = 0; i < n; i++) {
        m.position.push_back(vec3{ cos(2 * Pi * i / n) * radius, sin(2 * Pi * i / n) * radius, z_offset});
    }
    m.position.push_back(vec3{0, 0, z_offset });
    m.position.push_back(vec3{0, 0, z_offset + height });
    for (int i = 0; i < n; i++) {
        m.connectivity.push_back(uint3(i, n, (i + 1) % n));
        m.connectivity.push_back(uint3(i, (i + 1) % n, n + 1));
    }

    m.fill_empty_field();
    return m;
}

mesh create_tree()
{
    float h = 0.7f; // trunk height
    float r = 0.1f; // trunk radius

    // Create a brown trunk
    mesh trunk = create_cylinder_mesh(r, h);
    trunk.color.fill({ 0.4f, 0.3f, 0.3f });


    // Create a green foliage from 3 cones
    mesh foliage = create_cone_mesh(4 * r, 6 * r, 0.0f);      // base-cone
    foliage.push_back(create_cone_mesh(4 * r, 6 * r, 2 * r));   // middle-cone
    foliage.push_back(create_cone_mesh(4 * r, 6 * r, 4 * r));   // top-cone
    foliage.apply_translation_to_position({ 0,0,h });       // place foliage at the top of the trunk
    foliage.color.fill({ 0.4f, 0.6f, 0.3f });

    // The tree is composed of the trunk and the foliage
    mesh tree = trunk;
    tree.push_back(foliage);

    return tree;
}