💿🐜 Antkeeper source code
https://antkeeper.com
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209 lines
5.9 KiB
209 lines
5.9 KiB
/*
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* Copyright (C) 2021 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "entity/systems/terrain.hpp"
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#include "utility/fundamental-types.hpp"
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#include "entity/components/observer.hpp"
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#include "entity/components/terrain.hpp"
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#include "entity/components/celestial-body.hpp"
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#include "geom/quadtree.hpp"
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/**
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* A cube with six quadtrees as faces.
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*/
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struct quadtree_cube
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{
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typedef geom::quadtree32 quadtree_type;
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typedef quadtree_type::node_type node_type;
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void clear();
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/**
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* Refines the quadtree cube.
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*
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* @param threshold Function object which, given a quadsphere face index and quadtree node, returns `true` if the node should be subdivided, and `false` otherwise.
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*/
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void refine(const std::function<bool(std::uint8_t, node_type)>& threshold);
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quadtree_type faces[6];
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};
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void quadtree_cube::clear()
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{
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for (std::uint8_t i = 0; i < 6; ++i)
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faces[i].clear();
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}
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void quadtree_cube::refine(const std::function<bool(std::uint8_t, node_type)>& threshold)
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{
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for (std::uint8_t i = 0; i < 6; ++i)
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{
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for (auto it = faces[i].begin(); it != faces[i].end(); ++it)
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{
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node_type node = *it;
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if (threshold(i, node))
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faces[i].insert(quadtree_type::child(node, 0));
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}
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}
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}
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/*
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terrain_qtc.refine
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(
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[observer](std::uint8_t face_index, quadtree_cube_type::node_type node) -> bool
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{
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// Extract morton location code
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quadtree_type::node_type location = quadtree_type::location(node);
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quadtree_type::node_type morton_x;
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quadtree_type::node_type morton_y;
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geom::morton::decode(location, morton_x, morton_y);
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// Extract depth
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quadtree_type::node_type depth = quadtree_type::depth(node);
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// Determine fractional side length at depth
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float length = 1.0f / std::exp2(depth);
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// Determine fractional center of node
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float3 center;
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center.x = (static_cast<float>(morton_x) * length + length * 0.5f) * 2.0f - 1.0f;
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center.y = (static_cast<float>(morton_y) * length + length * 0.5f) * 2.0f - 1.0f;
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center.z = 1.0f;
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// Project node center onto unit sphere
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center = math::normalize(center);
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// Rotate projected center into sphere space
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center = face_rotations[face_index] * center;
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// Scale center by body radius
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center *= body_radius;
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// Calculate distance from observer to node center
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float distance = math::length(projected_center - observer_location);
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if (depth < 4 && distance < ...)
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return true;
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return false;
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}
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);
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*/
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/**
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* Queries a quad sphere for a list of leaf nodes. Leaf nodes will be inserted in the set
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*
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*
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* 0. If observer position changed more than x amount:
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* 1. Clear quad sphere
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* 2. Insert leaves based on observer distance.
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* 3. Pass quad sphere to tile generation function.
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* 3. Iterate leaves, deriving the face, depth, and morton location from each leaf index.
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* 4. Face, depth, and morton location can be used to determine latitude, longitude, and generate tiles.
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* 5. Generated tiles cached and added to scene.
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* 6. Record position of observer
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*/
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/**
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* Lat, lon determination:
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*
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* 1. Use morton location and depth to determine the x-y coordinates on a planar cube face.
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* 2. Project x-y coordinates onto sphere.
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* 3. Rotate coordinates according to face index.
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* 4. Convert cartesian coordinates to spherical coordinates.
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*/
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namespace entity {
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namespace system {
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terrain::terrain(entity::registry& registry):
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updatable(registry),
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patch_subdivisions(0),
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patch_vertex_size(0),
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patch_vertex_count(0),
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patch_vertex_data(nullptr)
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{
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// position + uv + normal + tangent + barycentric
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patch_vertex_size = 3 + 2 + 3 + 4 + 3;
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set_patch_subdivisions(0);
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registry.on_construct<component::terrain>().connect<&terrain::on_terrain_construct>(this);
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registry.on_destroy<component::terrain>().connect<&terrain::on_terrain_destroy>(this);
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}
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terrain::~terrain()
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{}
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void terrain::update(double t, double dt)
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{
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// Subdivide or collapse quad sphere
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registry.view<component::observer>().each(
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[&](entity::id observer_eid, const auto& observer)
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{
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// Skip observers with null reference body
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if (observer.reference_body_eid == entt::null)
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return;
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// Skip observers with non-body or non-terrestrial reference bodies
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if (!registry.has<component::celestial_body>(observer.reference_body_eid) ||
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!registry.has<component::terrain>(observer.reference_body_eid))
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return;
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const auto& celestial_body = registry.get<component::celestial_body>(observer.reference_body_eid);
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const auto& terrain = registry.get<component::terrain>(observer.reference_body_eid);
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// Haversine distance to all 6 faces, then recursively to children
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});
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}
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void terrain::set_patch_subdivisions(std::uint8_t n)
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{
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patch_subdivisions = n;
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// Recalculate number of vertices per patch
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patch_vertex_count = static_cast<std::size_t>(std::pow(std::exp2(patch_subdivisions) + 1, 2));
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// Resize patch vertex data buffer
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delete[] patch_vertex_data;
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patch_vertex_data = new float[patch_vertex_count * patch_vertex_size];
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}
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void terrain::on_terrain_construct(entity::registry& registry, entity::id entity_id, component::terrain& component)
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{
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// Build quad sphere
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}
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void terrain::on_terrain_destroy(entity::registry& registry, entity::id entity_id)
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{
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// Destroy quad sphere
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}
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void terrain::generate_patch()
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{
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}
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} // namespace system
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} // namespace entity
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