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Merge pull request #1447 from DarkflameUniverse/dpGrid_speedup
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chore: Use vector instead of forward_list for dpGrid for ~50% physics loop speed improvement
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@DarwinAnim8or
DarwinAnim8or authored Feb 8, 2024
2 parents 395e5c1 + e8aa491 commit 24f94ed
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Showing 3 changed files with 44 additions and 48 deletions.
2 changes: 1 addition & 1 deletion dPhysics/dpEntity.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -76,7 +76,7 @@ void dpEntity::CheckCollision(dpEntity* other) {
return;
}

bool wasFound = (m_CurrentlyCollidingObjects.find(other->GetObjectID()) != m_CurrentlyCollidingObjects.end());
bool wasFound = m_CurrentlyCollidingObjects.contains(other->GetObjectID());

bool isColliding = m_CollisionShape->IsColliding(other->GetShape());

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80 changes: 38 additions & 42 deletions dPhysics/dpGrid.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8,24 +8,14 @@ dpGrid::dpGrid(int numCells, int cellSize) {
CELL_SIZE = cellSize;
m_DeleteGrid = true;

//fill x
for (int i = 0; i < NUM_CELLS; i++) {
m_Cells.push_back(std::vector<std::forward_list<dpEntity*>>());
}

//fill z
for (int i = 0; i < NUM_CELLS; i++) {
for (int i = 0; i < NUM_CELLS; i++) {
m_Cells[i].push_back(std::forward_list<dpEntity*>());
}
}
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& y : x) { //y
for (auto en : y) {
for (auto& z : x) { //y
for (auto en : z) {
if (!en) continue;
delete en;
en = nullptr;
Expand All @@ -39,13 +29,12 @@ void dpGrid::Add(dpEntity* entity) {
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;

if (cellX < 0) cellX = 0;
if (cellZ < 0) cellZ = 0;
if (cellX >= NUM_CELLS) cellX = NUM_CELLS - 1;
if (cellZ >= NUM_CELLS) cellZ = NUM_CELLS - 1;
// 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_front(entity);
m_Cells[cellX][cellZ].push_back(entity);

//To verify that the object isn't gargantuan:
if (entity->GetScale() >= CELL_SIZE * 2 || entity->GetIsGargantuan())
Expand All @@ -59,39 +48,46 @@ void dpGrid::Move(dpEntity* entity, float x, float z) {
int cellX = (int)std::round(x) / dpGrid::CELL_SIZE + NUM_CELLS / 2;
int cellZ = (int)std::round(z) / dpGrid::CELL_SIZE + NUM_CELLS / 2;

if (cellX < 0) cellX = 0;
if (cellZ < 0) cellZ = 0;
if (cellX >= NUM_CELLS) cellX = NUM_CELLS - 1;
if (cellZ >= NUM_CELLS) cellZ = NUM_CELLS - 1;
// 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);

if (oldCellX < 0) oldCellX = 0;
if (oldCellZ < 0) oldCellZ = 0;
if (oldCellX >= NUM_CELLS) oldCellX = NUM_CELLS - 1;
if (oldCellZ >= NUM_CELLS) oldCellZ = 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 perv cell:
m_Cells[oldCellX][oldCellZ].remove(entity);
//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_front(entity);
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;

if (oldCellX < 0) oldCellX = 0;
if (oldCellZ < 0) oldCellZ = 0;
if (oldCellX >= NUM_CELLS) oldCellX = NUM_CELLS - 1;
if (oldCellZ >= NUM_CELLS) oldCellZ = NUM_CELLS - 1;
// 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);

m_Cells[oldCellX][oldCellZ].remove(entity);
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();
}

if (m_GargantuanObjects.find(entity->m_ObjectID) != m_GargantuanObjects.end())
m_GargantuanObjects.erase(entity->m_ObjectID);
m_GargantuanObjects.erase(entity->m_ObjectID);

if (entity) delete entity;
entity = nullptr;
Expand All @@ -100,8 +96,8 @@ void dpGrid::Delete(dpEntity* entity) {
void dpGrid::Update(float deltaTime) {
//Pre-update:
for (auto& x : m_Cells) { //x
for (auto& y : x) { //y
for (auto en : y) {
for (auto& z : x) { //y
for (auto en : z) {
if (!en) continue;
en->PreUpdate();
}
Expand All @@ -110,8 +106,8 @@ void dpGrid::Update(float deltaTime) {

//Actual collision detection update:
for (int x = 0; x < NUM_CELLS; x++) {
for (int y = 0; y < NUM_CELLS; y++) {
HandleCell(x, y, deltaTime);
for (int z = 0; z < NUM_CELLS; z++) {
HandleCell(x, z, deltaTime);
}
}
}
Expand Down Expand Up @@ -157,7 +153,7 @@ void dpGrid::HandleCell(int x, int z, float deltaTime) {
HandleEntity(en, other);
}

for (auto other : m_GargantuanObjects)
HandleEntity(en, other.second);
for (auto& [id, entity] : m_GargantuanObjects)
HandleEntity(en, entity);
}
}
10 changes: 5 additions & 5 deletions dPhysics/dpGrid.h
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Original file line number Diff line number Diff line change
@@ -1,8 +1,7 @@
#pragma once
#include <vector>
#include <list>
#include <forward_list>
#include <map>
#include <vector>

#include "dCommonVars.h"

class dpEntity;
Expand Down Expand Up @@ -30,15 +29,16 @@ class dpGrid {
*/
void SetDeleteGrid(bool value) { this->m_DeleteGrid = value; };

std::vector<std::vector<std::forward_list<dpEntity*>>> GetCells() { return this->m_Cells; };
// Intentional copy since this is only used when we delete this class to re-create it.
std::vector<std::vector<std::vector<dpEntity*>>> GetCells() { return this->m_Cells; };

private:
void HandleEntity(dpEntity* entity, dpEntity* other);
void HandleCell(int x, int z, float deltaTime);

private:
//cells on X, cells on Y for that X, then another vector that contains the entities within that cell.
std::vector<std::vector<std::forward_list<dpEntity*>>> m_Cells;
std::vector<std::vector<std::vector<dpEntity*>>> m_Cells;
std::map<LWOOBJID, dpEntity*> m_GargantuanObjects;
bool m_DeleteGrid = true;
};

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