DarkflameServer/dPhysics/dpGrid.cpp
2024-02-04 16:44:40 -08:00

160 lines
4.3 KiB
C++

#include "dpGrid.h"
#include "dpEntity.h"
#include <cmath>
dpGrid::dpGrid(int numCells, int cellSize) {
NUM_CELLS = numCells;
CELL_SIZE = cellSize;
m_DeleteGrid = true;
m_Cells.resize(NUM_CELLS, std::vector<std::vector<dpEntity*>>(NUM_CELLS));
}
dpGrid::~dpGrid() {
if (!this->m_DeleteGrid) return;
for (auto& x : m_Cells) { //x
for (auto& z : x) { //y
for (auto en : z) {
if (!en) continue;
delete en;
en = nullptr;
}
}
}
}
void dpGrid::Add(dpEntity* entity) {
//Determine which grid cell it's in.
int cellX = (int)std::round(entity->m_Position.x) / dpGrid::CELL_SIZE + NUM_CELLS / 2;
int cellZ = (int)std::round(entity->m_Position.z) / dpGrid::CELL_SIZE + NUM_CELLS / 2;
// Clamp values to the range [0, NUM_CELLS - 1]
cellX = std::clamp(cellX, 0, NUM_CELLS - 1);
cellZ = std::clamp(cellZ, 0, NUM_CELLS - 1);
//Add to cell:
m_Cells[cellX][cellZ].push_back(entity);
//To verify that the object isn't gargantuan:
if (entity->GetScale() >= CELL_SIZE * 2 || entity->GetIsGargantuan())
m_GargantuanObjects.insert(std::make_pair(entity->m_ObjectID, entity));
}
void dpGrid::Move(dpEntity* entity, float x, float z) {
int oldCellX = (int)std::round(entity->m_Position.x) / dpGrid::CELL_SIZE + NUM_CELLS / 2;
int oldCellZ = (int)std::round(entity->m_Position.z) / dpGrid::CELL_SIZE + NUM_CELLS / 2;
int cellX = (int)std::round(x) / dpGrid::CELL_SIZE + NUM_CELLS / 2;
int cellZ = (int)std::round(z) / dpGrid::CELL_SIZE + NUM_CELLS / 2;
// Clamp values to the range [0, NUM_CELLS - 1]
cellX = std::clamp(cellX, 0, NUM_CELLS - 1);
cellZ = std::clamp(cellZ, 0, NUM_CELLS - 1);
oldCellX = std::clamp(oldCellX, 0, NUM_CELLS - 1);
oldCellZ = std::clamp(oldCellZ, 0, NUM_CELLS - 1);
if (oldCellX == cellX && oldCellZ == cellZ) return;
//Remove from prev cell:
auto& cell = m_Cells[oldCellX][oldCellZ];
// For speed, find the single match and swap it with the last element, then pop_back.
auto toRemove = std::find(cell.begin(), cell.end(), entity);
if (toRemove != cell.end()) {
*toRemove = cell.back();
cell.pop_back();
}
//Add to the new cell
m_Cells[cellX][cellZ].push_back(entity);
}
void dpGrid::Delete(dpEntity* entity) {
if (!entity) return;
int oldCellX = (int)std::round(entity->m_Position.x) / dpGrid::CELL_SIZE + NUM_CELLS / 2;
int oldCellZ = (int)std::round(entity->m_Position.z) / dpGrid::CELL_SIZE + NUM_CELLS / 2;
// Clamp values to the range [0, NUM_CELLS - 1]
oldCellX = std::clamp(oldCellX, 0, NUM_CELLS - 1);
oldCellZ = std::clamp(oldCellZ, 0, NUM_CELLS - 1);
auto& cell = m_Cells[oldCellX][oldCellZ];
auto toRemove = std::find(cell.begin(), cell.end(), entity);
if (toRemove != cell.end()) {
*toRemove = cell.back();
cell.pop_back();
}
m_GargantuanObjects.erase(entity->m_ObjectID);
if (entity) delete entity;
entity = nullptr;
}
void dpGrid::Update(float deltaTime) {
//Pre-update:
for (auto& x : m_Cells) { //x
for (auto& z : x) { //y
for (auto en : z) {
if (!en) continue;
en->PreUpdate();
}
}
}
//Actual collision detection update:
for (int x = 0; x < NUM_CELLS; x++) {
for (int z = 0; z < NUM_CELLS; z++) {
HandleCell(x, z, deltaTime);
}
}
}
void dpGrid::HandleEntity(dpEntity* entity, dpEntity* other) {
if (!entity || !other) return;
if (other->GetIsStatic())
other->CheckCollision(entity); //swap "other" and "entity" if you want dyn objs to handle collisions.
}
void dpGrid::HandleCell(int x, int z, float deltaTime) {
auto& entities = m_Cells[x][z]; //vector of entities contained within this cell.
for (auto en : entities) {
if (!en) continue;
if (en->GetIsStatic() || en->GetSleeping()) continue;
//Check against all entities that are in the same cell as us
for (auto other : entities)
HandleEntity(en, other);
//To try neighbouring cells as well: (can be disabled if needed)
//we only check 4 of the 8 neighbouring cells, otherwise we'd get duplicates and cpu cycles wasted...
if (x > 0 && z > 0) {
for (auto other : m_Cells[x - 1][z - 1])
HandleEntity(en, other);
}
if (x > 0) {
for (auto other : m_Cells[x - 1][z])
HandleEntity(en, other);
}
if (z > 0) {
for (auto other : m_Cells[x][z - 1])
HandleEntity(en, other);
}
if (x > 0 && z < NUM_CELLS - 1) {
for (auto other : m_Cells[x - 1][z + 1])
HandleEntity(en, other);
}
for (auto& [id, entity] : m_GargantuanObjects)
HandleEntity(en, entity);
}
}