overte/libraries/entities/src/ParticleEffectEntityItem.cpp

536 lines
23 KiB
C++

//
// ParticleEffectEntityItem.cpp
// libraries/entities/src
//
// Some starter code for a particle simulation entity, which could ideally be used for a variety of effects.
// This is some really early and rough stuff here. It was enough for now to just get it up and running in the interface.
//
// Todo's and other notes:
// - The simulation should restart when the AnimationLoop's max frame is reached (or passed), but there doesn't seem
// to be a good way to set that max frame to something reasonable right now.
// - There seems to be a bug whereby entities on the edge of screen will just pop off or on. This is probably due
// to my lack of understanding of how entities in the octree are picked for rendering. I am updating the entity
// dimensions based on the bounds of the sim, but maybe I need to update a dirty flag or something.
// - This should support some kind of pre-roll of the simulation.
// - Just to get this out the door, I just did forward Euler integration. There are better ways.
// - Gravity always points along the Y axis. Support an actual gravity vector.
// - Add the ability to add arbitrary forces to the simulation.
// - Add controls for spread (which is currently hard-coded) and varying emission strength (not currently implemented).
// - Add drag.
// - Add some kind of support for collisions.
// - There's no synchronization of the simulation across clients at all. In fact, it's using rand() under the hood, so
// there's no gaurantee that different clients will see simulations that look anything like the other.
//
// Created by Jason Rickwald on 3/2/15.
//
// Distributed under the Apache License, Version 2.0.
// See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
//
#include <glm/gtx/transform.hpp>
#include <QtCore/QJsonDocument>
#include <QDebug>
#include <ByteCountCoding.h>
#include <GeometryUtil.h>
#include "EntityTree.h"
#include "EntityTreeElement.h"
#include "EntitiesLogging.h"
#include "EntityScriptingInterface.h"
#include "ParticleEffectEntityItem.h"
const xColor ParticleEffectEntityItem::DEFAULT_COLOR = { 255, 255, 255 };
const float ParticleEffectEntityItem::DEFAULT_ANIMATION_FRAME_INDEX = 0.0f;
const bool ParticleEffectEntityItem::DEFAULT_ANIMATION_IS_PLAYING = false;
const float ParticleEffectEntityItem::DEFAULT_ANIMATION_FPS = 30.0f;
const quint32 ParticleEffectEntityItem::DEFAULT_MAX_PARTICLES = 1000;
const float ParticleEffectEntityItem::DEFAULT_LIFESPAN = 3.0f;
const float ParticleEffectEntityItem::DEFAULT_EMIT_RATE = 15.0f;
const glm::vec3 ParticleEffectEntityItem::DEFAULT_EMIT_VELOCITY(0.0f, 0.0f, 0.0f);
const glm::vec3 ParticleEffectEntityItem::DEFAULT_VELOCITY_SPREAD(0.0f, 0.0f, 0.0f);
const glm::vec3 ParticleEffectEntityItem::DEFAULT_EMIT_ACCELERATION(0.0f, 0.0f, 0.0f);
const float ParticleEffectEntityItem::DEFAULT_PARTICLE_RADIUS = 0.025f;
const QString ParticleEffectEntityItem::DEFAULT_TEXTURES = "";
EntityItemPointer ParticleEffectEntityItem::factory(const EntityItemID& entityID, const EntityItemProperties& properties) {
return std::make_shared<ParticleEffectEntityItem>(entityID, properties);
}
// our non-pure virtual subclass for now...
ParticleEffectEntityItem::ParticleEffectEntityItem(const EntityItemID& entityItemID, const EntityItemProperties& properties) :
EntityItem(entityItemID),
_maxParticles(DEFAULT_MAX_PARTICLES),
_lifespan(DEFAULT_LIFESPAN),
_emitRate(DEFAULT_EMIT_RATE),
_emitVelocity(DEFAULT_EMIT_VELOCITY),
_emitAcceleration(DEFAULT_EMIT_ACCELERATION),
_particleRadius(DEFAULT_PARTICLE_RADIUS),
_lastAnimated(usecTimestampNow()),
_animationLoop(),
_animationSettings(),
_textures(DEFAULT_TEXTURES),
_texturesChangedFlag(false),
_shapeType(SHAPE_TYPE_NONE),
_particleLifetimes(DEFAULT_MAX_PARTICLES, 0.0f),
_particlePositions(DEFAULT_MAX_PARTICLES, glm::vec3(0.0f, 0.0f, 0.0f)),
_particleVelocities(DEFAULT_MAX_PARTICLES, glm::vec3(0.0f, 0.0f, 0.0f)),
_timeUntilNextEmit(0.0f),
_particleHeadIndex(0),
_particleTailIndex(0),
_particleMaxBound(glm::vec3(1.0f, 1.0f, 1.0f)),
_particleMinBound(glm::vec3(-1.0f, -1.0f, -1.0f)) {
_type = EntityTypes::ParticleEffect;
setColor(DEFAULT_COLOR);
setProperties(properties);
}
ParticleEffectEntityItem::~ParticleEffectEntityItem() {
}
void ParticleEffectEntityItem::setLifespan(float lifespan) {
_lifespan = lifespan;
}
void ParticleEffectEntityItem::setEmitVelocity(glm::vec3 emitVelocity) {
_emitVelocity = emitVelocity;
}
void ParticleEffectEntityItem::setVelocitySpread(glm::vec3 velocitySpread) {
_velocitySpread = velocitySpread;
}
void ParticleEffectEntityItem::setEmitAcceleration(glm::vec3 emitAcceleration) {
_emitAcceleration = emitAcceleration;
}
void ParticleEffectEntityItem::setParticleRadius(float particleRadius) {
_particleRadius = particleRadius;
}
EntityItemProperties ParticleEffectEntityItem::getProperties() const {
EntityItemProperties properties = EntityItem::getProperties(); // get the properties from our base class
COPY_ENTITY_PROPERTY_TO_PROPERTIES(color, getXColor);
COPY_ENTITY_PROPERTY_TO_PROPERTIES(animationIsPlaying, getAnimationIsPlaying);
COPY_ENTITY_PROPERTY_TO_PROPERTIES(animationFrameIndex, getAnimationFrameIndex);
COPY_ENTITY_PROPERTY_TO_PROPERTIES(animationFPS, getAnimationFPS);
COPY_ENTITY_PROPERTY_TO_PROPERTIES(glowLevel, getGlowLevel);
COPY_ENTITY_PROPERTY_TO_PROPERTIES(animationSettings, getAnimationSettings);
COPY_ENTITY_PROPERTY_TO_PROPERTIES(shapeType, getShapeType);
COPY_ENTITY_PROPERTY_TO_PROPERTIES(maxParticles, getMaxParticles);
COPY_ENTITY_PROPERTY_TO_PROPERTIES(lifespan, getLifespan);
COPY_ENTITY_PROPERTY_TO_PROPERTIES(emitRate, getEmitRate);
COPY_ENTITY_PROPERTY_TO_PROPERTIES(emitVelocity, getEmitVelocity);
COPY_ENTITY_PROPERTY_TO_PROPERTIES(emitAcceleration, getEmitAcceleration);
COPY_ENTITY_PROPERTY_TO_PROPERTIES(particleRadius, getParticleRadius);
COPY_ENTITY_PROPERTY_TO_PROPERTIES(textures, getTextures);
return properties;
}
bool ParticleEffectEntityItem::setProperties(const EntityItemProperties& properties) {
bool somethingChanged = EntityItem::setProperties(properties); // set the properties in our base class
SET_ENTITY_PROPERTY_FROM_PROPERTIES(color, setColor);
SET_ENTITY_PROPERTY_FROM_PROPERTIES(animationIsPlaying, setAnimationIsPlaying);
SET_ENTITY_PROPERTY_FROM_PROPERTIES(animationFrameIndex, setAnimationFrameIndex);
SET_ENTITY_PROPERTY_FROM_PROPERTIES(animationFPS, setAnimationFPS);
SET_ENTITY_PROPERTY_FROM_PROPERTIES(glowLevel, setGlowLevel);
SET_ENTITY_PROPERTY_FROM_PROPERTIES(animationSettings, setAnimationSettings);
SET_ENTITY_PROPERTY_FROM_PROPERTIES(shapeType, updateShapeType);
SET_ENTITY_PROPERTY_FROM_PROPERTIES(maxParticles, setMaxParticles);
SET_ENTITY_PROPERTY_FROM_PROPERTIES(lifespan, setLifespan);
SET_ENTITY_PROPERTY_FROM_PROPERTIES(emitRate, setEmitRate);
SET_ENTITY_PROPERTY_FROM_PROPERTIES(emitVelocity, setEmitVelocity);
SET_ENTITY_PROPERTY_FROM_PROPERTIES(emitAcceleration, setEmitAcceleration);
SET_ENTITY_PROPERTY_FROM_PROPERTIES(particleRadius, setParticleRadius);
SET_ENTITY_PROPERTY_FROM_PROPERTIES(textures, setTextures);
SET_ENTITY_PROPERTY_FROM_PROPERTIES(velocitySpread, setVelocitySpread);
if (somethingChanged) {
bool wantDebug = false;
if (wantDebug) {
uint64_t now = usecTimestampNow();
int elapsed = now - getLastEdited();
qCDebug(entities) << "ParticleEffectEntityItem::setProperties() AFTER update... edited AGO=" << elapsed <<
"now=" << now << " getLastEdited()=" << getLastEdited();
}
setLastEdited(properties.getLastEdited());
}
return somethingChanged;
}
int ParticleEffectEntityItem::readEntitySubclassDataFromBuffer(const unsigned char* data, int bytesLeftToRead,
ReadBitstreamToTreeParams& args,
EntityPropertyFlags& propertyFlags, bool overwriteLocalData) {
int bytesRead = 0;
const unsigned char* dataAt = data;
READ_ENTITY_PROPERTY(PROP_COLOR, rgbColor, setColor);
// Because we're using AnimationLoop which will reset the frame index if you change it's running state
// we want to read these values in the order they appear in the buffer, but call our setters in an
// order that allows AnimationLoop to preserve the correct frame rate.
float animationFPS = getAnimationFPS();
float animationFrameIndex = getAnimationFrameIndex();
bool animationIsPlaying = getAnimationIsPlaying();
READ_ENTITY_PROPERTY(PROP_ANIMATION_FPS, float, setAnimationFPS);
READ_ENTITY_PROPERTY(PROP_ANIMATION_FRAME_INDEX, float, setAnimationFrameIndex);
READ_ENTITY_PROPERTY(PROP_ANIMATION_PLAYING, bool, setAnimationIsPlaying);
if (propertyFlags.getHasProperty(PROP_ANIMATION_PLAYING)) {
if (animationIsPlaying != getAnimationIsPlaying()) {
setAnimationIsPlaying(animationIsPlaying);
}
}
if (propertyFlags.getHasProperty(PROP_ANIMATION_FPS)) {
setAnimationFPS(animationFPS);
}
if (propertyFlags.getHasProperty(PROP_ANIMATION_FRAME_INDEX)) {
setAnimationFrameIndex(animationFrameIndex);
}
READ_ENTITY_PROPERTY(PROP_ANIMATION_SETTINGS, QString, setAnimationSettings);
READ_ENTITY_PROPERTY(PROP_SHAPE_TYPE, ShapeType, updateShapeType);
READ_ENTITY_PROPERTY(PROP_MAX_PARTICLES, quint32, setMaxParticles);
READ_ENTITY_PROPERTY(PROP_LIFESPAN, float, setLifespan);
READ_ENTITY_PROPERTY(PROP_EMIT_RATE, float, setEmitRate);
READ_ENTITY_PROPERTY(PROP_EMIT_VELOCITY, glm::vec3, setEmitVelocity);
READ_ENTITY_PROPERTY(PROP_EMIT_ACCELERATION, glm::vec3, setEmitAcceleration);
READ_ENTITY_PROPERTY(PROP_PARTICLE_RADIUS, float, setParticleRadius);
READ_ENTITY_PROPERTY(PROP_TEXTURES, QString, setTextures);
READ_ENTITY_PROPERTY(PROP_VELOCITY_SPREAD, glm::vec3, setVelocitySpread);
return bytesRead;
}
// TODO: eventually only include properties changed since the params.lastViewFrustumSent time
EntityPropertyFlags ParticleEffectEntityItem::getEntityProperties(EncodeBitstreamParams& params) const {
EntityPropertyFlags requestedProperties = EntityItem::getEntityProperties(params);
requestedProperties += PROP_COLOR;
requestedProperties += PROP_ANIMATION_FPS;
requestedProperties += PROP_ANIMATION_FRAME_INDEX;
requestedProperties += PROP_ANIMATION_PLAYING;
requestedProperties += PROP_ANIMATION_SETTINGS;
requestedProperties += PROP_SHAPE_TYPE;
requestedProperties += PROP_MAX_PARTICLES;
requestedProperties += PROP_LIFESPAN;
requestedProperties += PROP_EMIT_RATE;
requestedProperties += PROP_EMIT_VELOCITY;
requestedProperties += PROP_EMIT_ACCELERATION;
requestedProperties += PROP_PARTICLE_RADIUS;
requestedProperties += PROP_TEXTURES;
requestedProperties += PROP_VELOCITY_SPREAD;
return requestedProperties;
}
void ParticleEffectEntityItem::appendSubclassData(OctreePacketData* packetData, EncodeBitstreamParams& params,
EntityTreeElementExtraEncodeData* modelTreeElementExtraEncodeData,
EntityPropertyFlags& requestedProperties,
EntityPropertyFlags& propertyFlags,
EntityPropertyFlags& propertiesDidntFit,
int& propertyCount,
OctreeElement::AppendState& appendState) const {
bool successPropertyFits = true;
APPEND_ENTITY_PROPERTY(PROP_COLOR, getColor());
APPEND_ENTITY_PROPERTY(PROP_ANIMATION_FPS, getAnimationFPS());
APPEND_ENTITY_PROPERTY(PROP_ANIMATION_FRAME_INDEX, getAnimationFrameIndex());
APPEND_ENTITY_PROPERTY(PROP_ANIMATION_PLAYING, getAnimationIsPlaying());
APPEND_ENTITY_PROPERTY(PROP_ANIMATION_SETTINGS, getAnimationSettings());
APPEND_ENTITY_PROPERTY(PROP_SHAPE_TYPE, (uint32_t)getShapeType());
APPEND_ENTITY_PROPERTY(PROP_MAX_PARTICLES, getMaxParticles());
APPEND_ENTITY_PROPERTY(PROP_LIFESPAN, getLifespan());
APPEND_ENTITY_PROPERTY(PROP_EMIT_RATE, getEmitRate());
APPEND_ENTITY_PROPERTY(PROP_EMIT_VELOCITY, getEmitVelocity());
APPEND_ENTITY_PROPERTY(PROP_EMIT_ACCELERATION, getEmitAcceleration());
APPEND_ENTITY_PROPERTY(PROP_PARTICLE_RADIUS, getParticleRadius());
APPEND_ENTITY_PROPERTY(PROP_TEXTURES, getTextures());
APPEND_ENTITY_PROPERTY(PROP_VELOCITY_SPREAD, getVelocitySpread());
}
bool ParticleEffectEntityItem::isAnimatingSomething() const {
// keep animating if there are particles still alive.
return (getAnimationIsPlaying() || getLivingParticleCount() > 0) && getAnimationFPS() != 0.0f;
}
bool ParticleEffectEntityItem::needsToCallUpdate() const {
return true;
}
void ParticleEffectEntityItem::update(const quint64& now) {
float deltaTime = (float)(now - _lastAnimated) / (float)USECS_PER_SECOND;
_lastAnimated = now;
// only advance the frame index if we're playing
if (getAnimationIsPlaying()) {
_animationLoop.simulate(deltaTime);
}
if (isAnimatingSomething()) {
stepSimulation(deltaTime);
}
EntityItem::update(now); // let our base class handle it's updates...
}
void ParticleEffectEntityItem::debugDump() const {
quint64 now = usecTimestampNow();
qCDebug(entities) << "PA EFFECT EntityItem id:" << getEntityItemID() << "---------------------------------------------";
qCDebug(entities) << " color:" << _color[0] << "," << _color[1] << "," << _color[2];
qCDebug(entities) << " position:" << debugTreeVector(getPosition());
qCDebug(entities) << " dimensions:" << debugTreeVector(getDimensions());
qCDebug(entities) << " getLastEdited:" << debugTime(getLastEdited(), now);
}
void ParticleEffectEntityItem::updateShapeType(ShapeType type) {
if (type != _shapeType) {
_shapeType = type;
_dirtyFlags |= EntityItem::DIRTY_SHAPE | EntityItem::DIRTY_MASS;
}
}
void ParticleEffectEntityItem::setAnimationFrameIndex(float value) {
#ifdef WANT_DEBUG
if (isAnimatingSomething()) {
qCDebug(entities) << "ParticleEffectEntityItem::setAnimationFrameIndex()";
qCDebug(entities) << " value:" << value;
qCDebug(entities) << " was:" << _animationLoop.getFrameIndex();
}
#endif
_animationLoop.setFrameIndex(value);
}
void ParticleEffectEntityItem::setAnimationSettings(const QString& value) {
// the animations setting is a JSON string that may contain various animation settings.
// if it includes fps, frameIndex, or running, those values will be parsed out and
// will over ride the regular animation settings
QJsonDocument settingsAsJson = QJsonDocument::fromJson(value.toUtf8());
QJsonObject settingsAsJsonObject = settingsAsJson.object();
QVariantMap settingsMap = settingsAsJsonObject.toVariantMap();
if (settingsMap.contains("fps")) {
float fps = settingsMap["fps"].toFloat();
setAnimationFPS(fps);
}
if (settingsMap.contains("frameIndex")) {
float frameIndex = settingsMap["frameIndex"].toFloat();
#ifdef WANT_DEBUG
if (isAnimatingSomething()) {
qCDebug(entities) << "ParticleEffectEntityItem::setAnimationSettings() calling setAnimationFrameIndex()...";
qCDebug(entities) << " settings:" << value;
qCDebug(entities) << " settingsMap[frameIndex]:" << settingsMap["frameIndex"];
qCDebug(entities, " frameIndex: %20.5f", frameIndex);
}
#endif
setAnimationFrameIndex(frameIndex);
}
if (settingsMap.contains("running")) {
bool running = settingsMap["running"].toBool();
if (running != getAnimationIsPlaying()) {
setAnimationIsPlaying(running);
}
}
if (settingsMap.contains("firstFrame")) {
float firstFrame = settingsMap["firstFrame"].toFloat();
setAnimationFirstFrame(firstFrame);
}
if (settingsMap.contains("lastFrame")) {
float lastFrame = settingsMap["lastFrame"].toFloat();
setAnimationLastFrame(lastFrame);
}
if (settingsMap.contains("loop")) {
bool loop = settingsMap["loop"].toBool();
setAnimationLoop(loop);
}
if (settingsMap.contains("hold")) {
bool hold = settingsMap["hold"].toBool();
setAnimationHold(hold);
}
if (settingsMap.contains("startAutomatically")) {
bool startAutomatically = settingsMap["startAutomatically"].toBool();
setAnimationStartAutomatically(startAutomatically);
}
_animationSettings = value;
_dirtyFlags |= EntityItem::DIRTY_UPDATEABLE;
}
void ParticleEffectEntityItem::setAnimationIsPlaying(bool value) {
_dirtyFlags |= EntityItem::DIRTY_UPDATEABLE;
_animationLoop.setRunning(value);
}
void ParticleEffectEntityItem::setAnimationFPS(float value) {
_dirtyFlags |= EntityItem::DIRTY_UPDATEABLE;
_animationLoop.setFPS(value);
}
QString ParticleEffectEntityItem::getAnimationSettings() const {
// the animations setting is a JSON string that may contain various animation settings.
// if it includes fps, frameIndex, or running, those values will be parsed out and
// will over ride the regular animation settings
QString value = _animationSettings;
QJsonDocument settingsAsJson = QJsonDocument::fromJson(value.toUtf8());
QJsonObject settingsAsJsonObject = settingsAsJson.object();
QVariantMap settingsMap = settingsAsJsonObject.toVariantMap();
QVariant fpsValue(getAnimationFPS());
settingsMap["fps"] = fpsValue;
QVariant frameIndexValue(getAnimationFrameIndex());
settingsMap["frameIndex"] = frameIndexValue;
QVariant runningValue(getAnimationIsPlaying());
settingsMap["running"] = runningValue;
QVariant firstFrameValue(getAnimationFirstFrame());
settingsMap["firstFrame"] = firstFrameValue;
QVariant lastFrameValue(getAnimationLastFrame());
settingsMap["lastFrame"] = lastFrameValue;
QVariant loopValue(getAnimationLoop());
settingsMap["loop"] = loopValue;
QVariant holdValue(getAnimationHold());
settingsMap["hold"] = holdValue;
QVariant startAutomaticallyValue(getAnimationStartAutomatically());
settingsMap["startAutomatically"] = startAutomaticallyValue;
settingsAsJsonObject = QJsonObject::fromVariantMap(settingsMap);
QJsonDocument newDocument(settingsAsJsonObject);
QByteArray jsonByteArray = newDocument.toJson(QJsonDocument::Compact);
QString jsonByteString(jsonByteArray);
return jsonByteString;
}
void ParticleEffectEntityItem::extendBounds(const glm::vec3& point) {
_particleMinBound.x = glm::min(_particleMinBound.x, point.x);
_particleMinBound.y = glm::min(_particleMinBound.y, point.y);
_particleMinBound.z = glm::min(_particleMinBound.z, point.z);
_particleMaxBound.x = glm::max(_particleMaxBound.x, point.x);
_particleMaxBound.y = glm::max(_particleMaxBound.y, point.y);
_particleMaxBound.z = glm::max(_particleMaxBound.z, point.z);
}
void ParticleEffectEntityItem::integrateParticle(quint32 index, float deltaTime) {
glm::vec3 atSquared(0.5f * _emitAcceleration.x * deltaTime * deltaTime, 0.5f * _emitAcceleration.y * deltaTime * deltaTime, 0.5f * _emitAcceleration.z * deltaTime * deltaTime);
glm::vec3 at(0.0f, _emitAcceleration.y * deltaTime, 0.0f);
_particlePositions[index] += _particleVelocities[index] * deltaTime + atSquared;
_particleVelocities[index] += at;
}
void ParticleEffectEntityItem::stepSimulation(float deltaTime) {
_particleMinBound = glm::vec3(-1.0f, -1.0f, -1.0f);
_particleMaxBound = glm::vec3(1.0f, 1.0f, 1.0f);
// update particles between head and tail
for (quint32 i = _particleHeadIndex; i != _particleTailIndex; i = (i + 1) % _maxParticles) {
_particleLifetimes[i] -= deltaTime;
// if particle has died.
if (_particleLifetimes[i] <= 0.0f) {
// move head forward
_particleHeadIndex = (_particleHeadIndex + 1) % _maxParticles;
}
else {
integrateParticle(i, deltaTime);
extendBounds(_particlePositions[i]);
}
}
// emit new particles, but only if animaiton is playing
if (getAnimationIsPlaying()) {
float timeLeftInFrame = deltaTime;
while (_timeUntilNextEmit < timeLeftInFrame) {
timeLeftInFrame -= _timeUntilNextEmit;
_timeUntilNextEmit = 1.0f / _emitRate;
// emit a new particle at tail index.
quint32 i = _particleTailIndex;
_particleLifetimes[i] = _lifespan;
// jitter the _emitVelocity by a random offset
glm::vec3 randOffset;
randOffset.x = -_velocitySpread.x + randFloat() * (_velocitySpread.x * 2.0f);
randOffset.y = -_velocitySpread.y + randFloat() * (_velocitySpread.y * 2.0f);
randOffset.z = -_velocitySpread.z + randFloat() * (_velocitySpread.z * 2.0f);
// set initial conditions
_particlePositions[i] = glm::vec3(0.0f, 0.0f, 0.0f);
_particleVelocities[i] = _emitVelocity + randOffset;
integrateParticle(i, timeLeftInFrame);
extendBounds(_particlePositions[i]);
_particleTailIndex = (_particleTailIndex + 1) % _maxParticles;
// overflow! move head forward by one.
// because the case of head == tail indicates an empty array, not a full one.
// This can drop an existing older particle, but this is by design, newer particles are a higher priority.
if (_particleTailIndex == _particleHeadIndex) {
_particleHeadIndex = (_particleHeadIndex + 1) % _maxParticles;
}
}
_timeUntilNextEmit -= timeLeftInFrame;
}
}
void ParticleEffectEntityItem::setMaxParticles(quint32 maxParticles) {
if (_maxParticles != maxParticles) {
_maxParticles = maxParticles;
// TODO: try to do something smart here and preserve the state of existing particles.
// resize vectors
_particleLifetimes.resize(_maxParticles);
_particlePositions.resize(_maxParticles);
_particleVelocities.resize(_maxParticles);
// effectivly clear all particles and start emitting new ones from scratch.
_particleHeadIndex = 0;
_particleTailIndex = 0;
_timeUntilNextEmit = 0.0f;
}
}
// because particles are in a ring buffer, this isn't trivial
quint32 ParticleEffectEntityItem::getLivingParticleCount() const {
if (_particleTailIndex >= _particleHeadIndex) {
return _particleTailIndex - _particleHeadIndex;
} else {
return (_maxParticles - _particleHeadIndex) + _particleTailIndex;
}
}