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#include "terrain.h"
#include "gfx/models/texture.h"
#include <array>
#include <cache.h>
#include <cmath>
#include <cstddef>
#include <gfx/gl/shader.h>
#include <gfx/gl/transform.h>
#include <gfx/models/vertex.hpp>
#include <glm/glm.hpp>
#include <random>
Terrain::Terrain() :
m_vertexArrayObject {}, m_vertexArrayBuffers {}, texture {Texture::cachedTexture.get("res/terrain.png")}
{
constexpr auto size {241}; // Vertices
constexpr auto offset {(size - 1) / 2};
constexpr auto verticesCount = size * size;
constexpr auto resolution = 10; // Grid size
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
vertices.reserve(verticesCount + 4);
vertices.resize(verticesCount, {{}, {}, {}});
// Initial coordinates
for (auto z = 0; z < size; z += 1) {
for (auto x = 0; x < size; x += 1) {
auto & vertex = vertices[x + (z * size)];
vertex.pos = {resolution * (x - offset), -1.5, resolution * (z - offset)};
vertex.normal = {0, 1, 0};
vertex.texCoord = {(x % 2) / 2.01, (z % 2) / 2.01};
}
}
// Add hills
std::mt19937 gen(std::random_device {}());
std::uniform_int_distribution<> rpos(2, size - 2);
std::uniform_int_distribution<> rsize(10, 20);
std::uniform_int_distribution<> rheight(1, 3);
for (int h = 0; h < 500;) {
const glm::ivec2 hpos {rpos(gen), rpos(gen)};
const glm::ivec2 hsize {rsize(gen), rsize(gen)};
if (const auto lim1 = hpos - hsize; lim1.x > 0 && lim1.y > 0) {
if (const auto lim2 = hpos + hsize; lim2.x < size && lim2.y < size) {
auto height {rheight(gen)};
const glm::ivec2 hsizesqrd {hsize.x * hsize.x, hsize.y * hsize.y};
for (auto z = lim1.y; z < lim2.y; z += 1) {
for (auto x = lim1.x; x < lim2.x; x += 1) {
const auto dist {hpos - glm::ivec2 {x, z}};
const glm::ivec2 distsqrd {dist.x * dist.x, dist.y * dist.y};
if ((pow(x - hpos.x, 2) / pow(hsize.x, 2)) + (pow(z - hpos.y, 2) / pow(hsize.y, 2)) <= 1.0) {
auto & vertex = vertices[x + (z * size)];
vertex.pos.y += height;
}
}
}
h += 1;
}
}
}
finish(size, size, resolution);
}
void
Terrain::finish(unsigned int width, unsigned int height, unsigned int resolution)
{
const auto tilesCount = (width - 1) * (height - 1);
const auto trianglesCount = tilesCount * 2;
const auto indicesCount = trianglesCount * 3;
indices.reserve(indicesCount + 6);
// Indices
for (auto z = 0U; z < height - 1; z += 1) {
for (auto x = 0U; x < width - 1; x += 1) {
indices.push_back(x + (z * width));
indices.push_back((x + 1) + ((z + 1) * width));
indices.push_back((x + 1) + (z * width));
indices.push_back(x + (z * width));
indices.push_back(x + ((z + 1) * width));
indices.push_back((x + 1) + ((z + 1) * width));
}
}
// Normals
for (auto z = 1U; z < height - 1; z += 1) {
for (auto x = 1U; x < width - 1; x += 1) {
const auto a = v(width, x - 1, z).pos;
const auto b = v(width, x, z - 1).pos;
const auto c = v(width, x + 1, z).pos;
const auto d = v(width, x, z + 1).pos;
v(width, x, z).normal = -glm::normalize(glm::cross(c - a, d - b));
}
}
const auto verticesCount = vertices.size();
// Add water
const auto extentx {(int)((width - 1) * resolution / 2)};
const auto extentz {(int)((height - 1) * resolution / 2)};
vertices.emplace_back(glm::vec3 {-extentx, 0, -extentz}, glm::vec2 {0.5, 0.0}, glm::vec3 {0, 1, 0});
vertices.emplace_back(glm::vec3 {-extentx, 0, extentz}, glm::vec2 {0.5, 0.5}, glm::vec3 {0, 1, 0});
vertices.emplace_back(glm::vec3 {extentx, 0, extentz}, glm::vec2 {1, 0.5}, glm::vec3 {0, 1, 0});
vertices.emplace_back(glm::vec3 {extentx, 0, -extentz}, glm::vec2 {1, 0.0}, glm::vec3 {0, 1, 0});
indices.push_back(verticesCount);
indices.push_back(verticesCount + 1);
indices.push_back(verticesCount + 2);
indices.push_back(verticesCount);
indices.push_back(verticesCount + 2);
indices.push_back(verticesCount + 3);
glGenVertexArrays(1, &m_vertexArrayObject);
glBindVertexArray(m_vertexArrayObject);
glGenBuffers(2, m_vertexArrayBuffers.data());
glBindBuffer(GL_ARRAY_BUFFER, m_vertexArrayBuffers[0]);
glBufferData(GL_ARRAY_BUFFER, sizeof(Vertex) * vertices.size(), vertices.data(), GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void *)offsetof(Vertex, pos));
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void *)offsetof(Vertex, texCoord));
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void *)offsetof(Vertex, normal));
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_vertexArrayBuffers[1]);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices[0]) * indices.size(), indices.data(), GL_STATIC_DRAW);
glBindVertexArray(0);
}
Vertex &
Terrain::v(unsigned int width, unsigned int x, unsigned int z)
{
return vertices[x + (z * width)];
}
Terrain::~Terrain()
{
glDeleteBuffers(NUM_BUFFERS, m_vertexArrayBuffers.data());
glDeleteVertexArrays(1, &m_vertexArrayObject);
}
static const Transform identity {};
static const auto identityModel {identity.GetModel()};
void
Terrain::render(const Shader & shader) const
{
shader.setModel(identityModel);
texture->Bind();
glBindVertexArray(m_vertexArrayObject);
glDrawElementsBaseVertex(GL_TRIANGLES, indices.size(), GL_UNSIGNED_INT, nullptr, 0);
glBindVertexArray(0);
}
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