💿🐜 Antkeeper source code https://antkeeper.com
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/*
* Copyright (C) 2021 Christopher J. Howard
*
* This file is part of Antkeeper source code.
*
* Antkeeper source code is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Antkeeper source code is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
*/
#include "game/system/terrain.hpp"
#include "game/component/terrain.hpp"
#include "game/component/camera.hpp"
#include "geom/meshes/grid.hpp"
#include "geom/mesh-functions.hpp"
#include "geom/morton.hpp"
#include "geom/quadtree.hpp"
#include "geom/primitive/ray.hpp"
#include "gl/vertex-attribute.hpp"
#include "math/quaternion.hpp"
#include "render/vertex-attribute.hpp"
#include "utility/fundamental-types.hpp"
#include <functional>
#include <iostream>
namespace game {
namespace system {
terrain::terrain(entity::registry& registry):
updatable(registry),
patch_side_length(0.0f),
patch_subdivisions(0),
patch_material(nullptr),
elevation_function(nullptr),
scene_collection(nullptr),
patch_base_mesh(nullptr),
patch_vertex_size(0),
patch_vertex_stride(0),
patch_vertex_data(nullptr)
{
// Specify vertex size and stride
// (position + uv + normal + tangent + barycentric + target)
patch_vertex_size = 3 + 2 + 3 + 4 + 3 + 3;
patch_vertex_stride = patch_vertex_size * sizeof(float);
// Init quadtee node sizes at each depth
for (std::size_t i = 0; i <= quadtree_type::max_depth; ++i)
quadtree_node_size[i] = 0.0f;
std::cout << "quadtree cap: " << quadtree.max_size() << std::endl;
registry.on_construct<component::terrain>().connect<&terrain::on_terrain_construct>(this);
registry.on_update<component::terrain>().connect<&terrain::on_terrain_update>(this);
registry.on_destroy<component::terrain>().connect<&terrain::on_terrain_destroy>(this);
}
terrain::~terrain()
{
registry.on_construct<component::terrain>().disconnect<&terrain::on_terrain_construct>(this);
registry.on_update<component::terrain>().disconnect<&terrain::on_terrain_update>(this);
registry.on_destroy<component::terrain>().disconnect<&terrain::on_terrain_destroy>(this);
}
void terrain::update(double t, double dt)
{
// Clear quadtree
quadtree.clear();
// For each camera
this->registry.view<component::camera>().each
(
[&](entity::id camera_eid, const auto& camera)
{
if (!camera.object)
return;
const scene::camera& cam = *camera.object;
// for (int i = 0; i < 8; ++i)
// std::cout << "corner " << i << ": " << cam.get_view_frustum().get_corners()[i] << std::endl;
geom::primitive::ray<float, 3> rays[8];
rays[0] = cam.pick({-1, -1});
rays[1] = cam.pick({-1, 1});
rays[2] = cam.pick({ 1, 1});
rays[3] = cam.pick({ 1, -1});
float3 ntl = rays[0].origin;
float3 nbl = rays[1].origin;
float3 nbr = rays[2].origin;
float3 ntr = rays[3].origin;
float3 ftl = rays[0].origin + rays[0].direction * (cam.get_clip_far() - cam.get_clip_near());
float3 fbl = rays[1].origin + rays[1].direction * (cam.get_clip_far() - cam.get_clip_near());
float3 fbr = rays[2].origin + rays[2].direction * (cam.get_clip_far() - cam.get_clip_near());
float3 ftr = rays[3].origin + rays[3].direction * (cam.get_clip_far() - cam.get_clip_near());
// for (int i = 0; i < 8; ++i)
// std::cout << "ray or " << i << ": " << rays[i].origin << std::endl;
geom::convex_hull<float> hull(6);
hull.planes[0] = geom::plane<float>(ftl, fbl, nbl);
hull.planes[1] = geom::plane<float>(ntr, nbr, fbr);
hull.planes[2] = geom::plane<float>(fbl, fbr, nbr);
hull.planes[3] = geom::plane<float>(ftl, ntl, ntr);
hull.planes[4] = geom::plane<float>(ntl, nbl, nbr);
hull.planes[5] = geom::plane<float>(ftr, fbr, fbl);
geom::sphere<float> sphere;
sphere.center = cam.get_translation();
sphere.radius = patch_side_length;
//visit_quadtree(cam.get_view_frustum().get_bounds(), quadtree_type::root);
visit_quadtree(sphere, quadtree_type::root);
}
);
//std::cout << "qsize: " << quadtree.size() << std::endl;
std::size_t qvis = 0;
/// Toggle visibility of terrain scene objects
for (auto it = patches.begin(); it != patches.end(); ++it)
{
bool active = (quadtree.contains(it->first) && quadtree.is_leaf(it->first));
it->second->model_instance->set_active(active);
if (active)
++qvis;
}
//std::cout << "qvis: " << qvis << std::endl;
}
void terrain::set_patch_side_length(float length)
{
patch_side_length = length;
// Recalculate node sizes at each quadtree depth
for (std::size_t i = 0; i <= quadtree_type::max_depth; ++i)
{
quadtree_node_size[i] = std::exp2(quadtree_type::max_depth - i) * patch_side_length;
//std::cout << quadtree_node_size[i] << std::endl;
}
}
void terrain::set_patch_subdivisions(std::size_t n)
{
patch_subdivisions = n;
// Recalculate patch properties
patch_cell_count = (patch_subdivisions + 1) * (patch_subdivisions + 1);
patch_triangle_count = patch_cell_count * 2;
// Resize patch vertex data buffer
delete[] patch_vertex_data;
patch_vertex_data = new float[patch_triangle_count * 3 * patch_vertex_size];
// Resize patch buffers
std::size_t vertex_buffer_row_size = patch_subdivisions + 4;
std::size_t vertex_buffer_column_size = vertex_buffer_row_size;
patch_vertex_buffer.resize(vertex_buffer_row_size);
for (std::size_t i = 0; i < patch_vertex_buffer.size(); ++i)
patch_vertex_buffer[i].resize(vertex_buffer_column_size);
rebuild_patch_base_mesh();
}
void terrain::set_patch_material(::render::material* material)
{
patch_material = material;
}
void terrain::set_elevation_function(const std::function<float(float, float)>& f)
{
elevation_function = f;
}
void terrain::set_scene_collection(scene::collection* collection)
{
scene_collection = collection;
}
void terrain::on_terrain_construct(entity::registry& registry, entity::id entity_id)
{
}
void terrain::on_terrain_update(entity::registry& registry, entity::id entity_id)
{
}
void terrain::on_terrain_destroy(entity::registry& registry, entity::id entity_id)
{
}
float terrain::get_patch_size(quadtree_node_type node) const
{
return quadtree_node_size[quadtree_type::depth(node)];
}
float3 terrain::get_patch_center(quadtree_node_type node) const
{
const float node_size = get_patch_size(node);
const float node_offset = quadtree_node_size[0] * -0.5f + node_size * 0.5f;
// Extract node location from Morton location code
quadtree_type::node_type node_location = quadtree_type::location(node);
quadtree_type::node_type node_location_x;
quadtree_type::node_type node_location_y;
geom::morton::decode(node_location, node_location_x, node_location_y);
return float3
{
node_offset + static_cast<float>(node_location_x) * node_size,
0.0f,
node_offset + static_cast<float>(node_location_y) * node_size
};
}
void terrain::rebuild_patch_base_mesh()
{
// Rebuild grid
delete patch_base_mesh;
patch_base_mesh = geom::meshes::grid_xy(1.0f, patch_subdivisions, patch_subdivisions);
// Convert quads to triangle fans
for (std::size_t i = 0; i < patch_base_mesh->get_faces().size(); ++i)
{
geom::mesh::face* face = patch_base_mesh->get_faces()[i];
std::size_t edge_count = 1;
for (geom::mesh::edge* edge = face->edge->next; edge != face->edge; edge = edge->next)
++edge_count;
if (edge_count > 3)
{
geom::poke_face(*patch_base_mesh, face->index);
--i;
}
}
// Transform patch base mesh coordinates from XY plane to XZ plane
const math::quaternion<float> xy_to_xz = math::quaternion<float>::rotate_x(math::half_pi<float>);
for (geom::mesh::vertex* vertex: patch_base_mesh->get_vertices())
{
vertex->position = xy_to_xz * vertex->position;
}
}
void terrain::visit_quadtree(const geom::bounding_volume<float>& volume, quadtree_node_type node)
{
const float root_offset = quadtree_node_size[0] * -0.5f;
// Extract node depth
quadtree_type::node_type node_depth = quadtree_type::depth(node);
const float node_size = get_patch_size(node);
const float3 node_center = get_patch_center(node);
// Build node bounds AABB
geom::aabb<float> node_bounds;
node_bounds.min_point =
{
node_center.x() - node_size * 0.5f,
-std::numeric_limits<float>::infinity(),
node_center.z() - node_size * 0.5f
};
node_bounds.max_point =
{
node_bounds.min_point.x() + node_size,
std::numeric_limits<float>::infinity(),
node_bounds.min_point.z() + node_size
};
// If volume intersects node
if (volume.intersects(node_bounds))
{
// Subdivide leaf nodes
if (quadtree.is_leaf(node))
{
quadtree.insert(quadtree_type::child(node, 0));
for (quadtree_node_type i = 0; i < quadtree_type::children_per_node; ++i)
{
quadtree_node_type child = quadtree_type::child(node, i);
if (patches.find(child) == patches.end())
{
patch* child_patch = generate_patch(child);
patches[child] = child_patch;
scene_collection->add_object(child_patch->model_instance);
}
}
}
// Visit children
if (node_depth < quadtree_type::max_depth - 1)
{
for (quadtree_node_type i = 0; i < quadtree_type::children_per_node; ++i)
visit_quadtree(volume, quadtree_type::child(node, i));
}
}
}
geom::mesh* terrain::generate_patch_mesh(quadtree_node_type node) const
{
// Extract node depth
const quadtree_type::node_type node_depth = quadtree_type::depth(node);
// Get size of node at depth
const float node_size = quadtree_node_size[node_depth];
// Extract node Morton location code and decode location
const quadtree_type::node_type node_location = quadtree_type::location(node);
quadtree_type::node_type node_location_x;
quadtree_type::node_type node_location_y;
geom::morton::decode(node_location, node_location_x, node_location_y);
// Determine center of node
const float node_offset = quadtree_node_size[0] * -0.5f + node_size * 0.5f;
const float3 node_center =
{
node_offset + static_cast<float>(node_location_x) * node_size,
0.0f,
node_offset + static_cast<float>(node_location_y) * node_size
};
// Copy patch base mesh
geom::mesh* patch_mesh = new geom::mesh(*patch_base_mesh);
// Modify patch mesh vertex positions
for (geom::mesh::vertex* v: patch_mesh->get_vertices())
{
v->position.x() = node_center.x() + v->position.x() * node_size;
v->position.z() = node_center.z() + v->position.z() * node_size;
v->position.y() = elevation_function(v->position.x(), v->position.z());
}
return patch_mesh;
}
::render::model* terrain::generate_patch_model(quadtree_node_type node) const
{
// Get size and position of patch
const float patch_size = get_patch_size(node);
const float3 patch_center = get_patch_center(node);
// Calculate size of a patch cell
const float cell_size = patch_size / static_cast<float>(patch_subdivisions + 1);
const float half_cell_size = cell_size * 0.5f;
// Init patch bounds
geom::aabb<float> patch_bounds;
patch_bounds.min_point.x() = patch_center.x() - patch_size * 0.5f;
patch_bounds.min_point.y() = std::numeric_limits<float>::infinity();
patch_bounds.min_point.z() = patch_center.z() - patch_size * 0.5f;
patch_bounds.max_point.x() = patch_center.x() + patch_size * 0.5f;
patch_bounds.max_point.y() = -std::numeric_limits<float>::infinity();
patch_bounds.max_point.z() = patch_center.z() + patch_size * 0.5f;
// Calculate positions and UVs of patch vertices and immediately neighboring vertices
float3 first_vertex_position =
{
patch_bounds.min_point.x() - cell_size,
patch_center.y(),
patch_bounds.min_point.z() - cell_size
};
float3 vertex_position = first_vertex_position;
for (std::size_t i = 0; i < patch_vertex_buffer.size(); ++i)
{
// For each column
for (std::size_t j = 0; j < patch_vertex_buffer[i].size(); ++j)
{
// Calculate vertex elevation
vertex_position.y() = elevation_function(vertex_position.x(), vertex_position.z());
// Update patch bounds
patch_bounds.min_point.y() = std::min(patch_bounds.min_point.y(), vertex_position.y());
patch_bounds.max_point.y() = std::max(patch_bounds.max_point.y(), vertex_position.y());
// Update patch vertex position
patch_vertex_buffer[i][j].position = vertex_position;
// Calculate patch vertex UV
patch_vertex_buffer[i][j].uv.x() = (vertex_position.x() - patch_bounds.min_point.x()) / patch_size;
patch_vertex_buffer[i][j].uv.y() = (vertex_position.z() - patch_bounds.min_point.z()) / patch_size;
// Init patch vertex normal, tangent, and bitangent
patch_vertex_buffer[i][j].normal = {0, 0, 0};
patch_vertex_buffer[i][j].tangent = {0, 0, 0};
patch_vertex_buffer[i][j].bitangent = {0, 0, 0};
vertex_position.x() += cell_size;
}
vertex_position.z() += cell_size;
vertex_position.x() = first_vertex_position.x();
}
// Accumulate normals, tangents, and bitangents
for (std::size_t i = 0; i < patch_vertex_buffer.size() - 1; ++i)
{
for (std::size_t j = 0; j < patch_vertex_buffer[i].size() - 1; ++j)
{
patch_vertex& a = patch_vertex_buffer[i ][j];
patch_vertex& b = patch_vertex_buffer[i+1][j];
patch_vertex& c = patch_vertex_buffer[i ][j+1];
patch_vertex& d = patch_vertex_buffer[i+1][j+1];
auto add_ntb = [](auto& a, auto& b, auto& c)
{
const float3 ba = b.position - a.position;
const float3 ca = c.position - a.position;
const float2 uvba = b.uv - a.uv;
const float2 uvca = c.uv - a.uv;
const float3 normal = math::normalize(math::cross(ba, ca));
const float f = 1.0f / (uvba.x() * uvca.y() - uvca.x() * uvba.y());
const float3 tangent = (ba * uvca.y() - ca * uvba.y()) * f;
const float3 bitangent = (ba * -uvca.x() + ca * uvba.x()) * f;
a.normal += normal;
a.tangent += tangent;
a.bitangent += bitangent;
b.normal += normal;
b.tangent += tangent;
b.bitangent += bitangent;
c.normal += normal;
c.tangent += tangent;
c.bitangent += bitangent;
};
if ((j + i) % 2)
{
add_ntb(a, b, c);
add_ntb(c, b, d);
}
else
{
add_ntb(a, b, d);
add_ntb(a, d, c);
}
}
}
// Finalize normals, tangents, and bitangent signs of patch vertices
for (std::size_t i = 1; i < patch_vertex_buffer.size() - 1; ++i)
{
for (std::size_t j = 1; j < patch_vertex_buffer[i].size() - 1; ++j)
{
auto& vertex = patch_vertex_buffer[i][j];
// Normalize normal
vertex.normal = math::normalize(vertex.normal);
// Gram-Schmidt orthogonalize tangent
vertex.tangent = math::normalize(vertex.tangent - vertex.normal * math::dot(vertex.normal, vertex.tangent));
// Calculate bitangent sign
vertex.bitangent_sign = std::copysign(1.0f, math::dot(math::cross(vertex.normal, vertex.tangent), vertex.bitangent));
}
}
/*
0 subdivisions:
+---+---+---+
| |
+ +---+ +
| | | |
+ +---+ +
| |
+---+---+---+
1 subdivision:
+---+---+---+---+
| |
+ +---+---+ +
| | | | |
+ +---+---+ +
| | | | |
+ +---+---+ +
| |
+---+---+---+---+
2 subdivisions:
+---+---+---+---+---+
| |
+ +---+---+---+ +
| | | | | |
+ +---+---+---+ +
| | | | | |
+ +---+---+---+ +
| | | | | |
+ +---+---+---+ +
| |
+---+---+---+---+---+
*/
// For each row
float* v = patch_vertex_data;
for (std::size_t i = 1; i < patch_vertex_buffer.size() - 2; ++i)
{
// For each column
for (std::size_t j = 1; j < patch_vertex_buffer[i].size() - 2; ++j)
{
// a---c
// | |
// b---d
const patch_vertex& a = patch_vertex_buffer[i ][j];
const patch_vertex& b = patch_vertex_buffer[i+1][j];
const patch_vertex& c = patch_vertex_buffer[i ][j+1];
const patch_vertex& d = patch_vertex_buffer[i+1][j+1];
auto add_triangle = [&v](const patch_vertex& a, const patch_vertex& b, const patch_vertex& c)
{
auto add_vertex = [&v](const patch_vertex& vertex, const float3& barycentric)
{
// Position
*(v++) = vertex.position[0];
*(v++) = vertex.position[1];
*(v++) = vertex.position[2];
// UV
*(v++) = vertex.uv[0];
*(v++) = vertex.uv[1];
// Normal
*(v++) = vertex.normal[0];
*(v++) = vertex.normal[1];
*(v++) = vertex.normal[2];
/// Tangent
*(v++) = vertex.tangent[0];
*(v++) = vertex.tangent[1];
*(v++) = vertex.tangent[2];
*(v++) = vertex.bitangent_sign;
// Barycentric
*(v++) = barycentric[0];
*(v++) = barycentric[1];
*(v++) = barycentric[2];
// Morph target (LOD transition)
*(v++) = 0.0f;
*(v++) = 0.0f;
*(v++) = 0.0f;
};
add_vertex(a, float3{1, 0, 0});
add_vertex(b, float3{0, 1, 0});
add_vertex(c, float3{0, 0, 1});
};
if ((j + i) % 2)
{
add_triangle(a, b, c);
add_triangle(c, b, d);
}
else
{
add_triangle(a, b, d);
add_triangle(a, d, c);
}
}
}
// Allocate patch model
::render::model* patch_model = new ::render::model();
// Get model VBO and VAO
gl::vertex_buffer* vbo = patch_model->get_vertex_buffer();
gl::vertex_array* vao = patch_model->get_vertex_array();
// Resize model VBO and upload vertex data
vbo->resize(patch_triangle_count * 3 * patch_vertex_stride, patch_vertex_data);
std::size_t attribute_offset = 0;
// Define position vertex attribute
gl::vertex_attribute position_attribute;
position_attribute.buffer = vbo;
position_attribute.offset = attribute_offset;
position_attribute.stride = patch_vertex_stride;
position_attribute.type = gl::vertex_attribute_type::float_32;
position_attribute.components = 3;
attribute_offset += position_attribute.components * sizeof(float);
// Define UV vertex attribute
gl::vertex_attribute uv_attribute;
uv_attribute.buffer = vbo;
uv_attribute.offset = attribute_offset;
uv_attribute.stride = patch_vertex_stride;
uv_attribute.type = gl::vertex_attribute_type::float_32;
uv_attribute.components = 2;
attribute_offset += uv_attribute.components * sizeof(float);
// Define normal vertex attribute
gl::vertex_attribute normal_attribute;
normal_attribute.buffer = vbo;
normal_attribute.offset = attribute_offset;
normal_attribute.stride = patch_vertex_stride;
normal_attribute.type = gl::vertex_attribute_type::float_32;
normal_attribute.components = 3;
attribute_offset += normal_attribute.components * sizeof(float);
// Define tangent vertex attribute
gl::vertex_attribute tangent_attribute;
tangent_attribute.buffer = vbo;
tangent_attribute.offset = attribute_offset;
tangent_attribute.stride = patch_vertex_stride;
tangent_attribute.type = gl::vertex_attribute_type::float_32;
tangent_attribute.components = 4;
attribute_offset += tangent_attribute.components * sizeof(float);
// Define barycentric vertex attribute
gl::vertex_attribute barycentric_attribute;
barycentric_attribute.buffer = vbo;
barycentric_attribute.offset = attribute_offset;
barycentric_attribute.stride = patch_vertex_stride;
barycentric_attribute.type = gl::vertex_attribute_type::float_32;
barycentric_attribute.components = 3;
attribute_offset += barycentric_attribute.components * sizeof(float);
// Define target vertex attribute
gl::vertex_attribute target_attribute;
target_attribute.buffer = vbo;
target_attribute.offset = attribute_offset;
target_attribute.stride = patch_vertex_stride;
target_attribute.type = gl::vertex_attribute_type::float_32;
target_attribute.components = 3;
attribute_offset += target_attribute.components * sizeof(float);
// Bind vertex attributes to VAO
vao->bind(::render::vertex_attribute::position, position_attribute);
vao->bind(::render::vertex_attribute::uv, uv_attribute);
vao->bind(::render::vertex_attribute::normal, normal_attribute);
vao->bind(::render::vertex_attribute::tangent, tangent_attribute);
vao->bind(::render::vertex_attribute::barycentric, barycentric_attribute);
vao->bind(::render::vertex_attribute::target, target_attribute);
// Create model group
::render::model_group* patch_model_group = patch_model->add_group("terrain");
patch_model_group->set_material(patch_material);
patch_model_group->set_drawing_mode(gl::drawing_mode::triangles);
patch_model_group->set_start_index(0);
patch_model_group->set_index_count(patch_triangle_count * 3);
// Set patch model bounds
patch_model->set_bounds(patch_bounds);
//std::cout << "depth: " << quadtree_type::depth(node) << "; size: " << (patch_bounds.max_point + patch_bounds.min_point) * 0.5f << std::endl;
return patch_model;
}
terrain::patch* terrain::generate_patch(quadtree_node_type node)
{
patch* node_patch = new patch();
node_patch->mesh = nullptr;//generate_patch_mesh(node);
node_patch->model = generate_patch_model(node);
node_patch->model_instance = new scene::model_instance(node_patch->model);
return node_patch;
}
} // namespace system
} // namespace game