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 _emitDirection by a random offset
glm::vec3 randOffset;
randOffset.x = (randFloat() - 0.5f) * 0.25f * _emitStrength;
randOffset.y = (randFloat() - 0.5f) * 0.25f * _emitStrength;
randOffset.z = (randFloat() - 0.5f) * 0.25f * _emitStrength;
// set initial conditions
_particlePositions[i] = glm::vec3(0.0f, 0.0f, 0.0f);
_particleVelocities[i] = _emitDirection * _emitStrength + 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::stepSimulation(float deltaTime) {
// update particles between head and tail
int popCount = 0;
for (Particle& particle : _particles) {
particle.lifetime += deltaTime;
// if particle has died.
if (particle.lifetime >= _lifespan) {
// move head forward
popCount++;
} else {
// Otherwise update it
integrateParticle(particle, deltaTime);
}
}
_particles.erase(_particles.begin(), _particles.begin() + popCount);
// emit new particles, but only if we are emmitting
if (getIsEmitting() && _emitRate > 0.0f && _lifespan > 0.0f && _polarStart <= _polarFinish) {
float timeLeftInFrame = deltaTime;
while (_timeUntilNextEmit < timeLeftInFrame) {
// 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 (_particles.size() >= _maxParticles) {
_particles.pop_front();
}
// emit a new particle at tail index.
_particles.push_back(createParticle(glm::mix(_previousPosition, getPosition(),
(deltaTime - timeLeftInFrame) / deltaTime)));
auto particle = _particles.back();
particle.lifetime += timeLeftInFrame;
// Initialize it
integrateParticle(particle, deltaTime);
// Advance in frame
timeLeftInFrame -= _timeUntilNextEmit;
_timeUntilNextEmit = 1.0f / _emitRate;
}
_timeUntilNextEmit -= timeLeftInFrame;
}
_previousPosition = getPosition();
}
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 || _lifespan == 0.0f) {
// move head forward
_particleHeadIndex = (_particleHeadIndex + 1) % _maxParticles;
}
else {
float age = 1.0f - _particleLifetimes[i] / _lifespan; // 0.0 .. 1.0
updateRadius(i, age);
updateColor(i, age);
updateAlpha(i, age);
integrateParticle(i, deltaTime);
extendBounds(_particlePositions[i]);
}
}
// emit new particles, but only if we are emmitting
if (getIsEmitting() && _emitRate > 0.0f && _lifespan > 0.0f && _polarStart <= _polarFinish) {
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;
// Radius
if (_radiusSpread == 0.0f) {
_radiusStarts[i] = getRadiusStart();
_radiusMiddles[i] =_particleRadius;
_radiusFinishes[i] = getRadiusFinish();
} else {
float spreadMultiplier;
if (_particleRadius > 0.0f) {
spreadMultiplier = 1.0f + randFloatInRange(-1.0f, 1.0f) * _radiusSpread / _particleRadius;
} else {
spreadMultiplier = 1.0f;
}
_radiusStarts[i] =
glm::clamp(spreadMultiplier * getRadiusStart(), MINIMUM_PARTICLE_RADIUS, MAXIMUM_PARTICLE_RADIUS);
_radiusMiddles[i] =
glm::clamp(spreadMultiplier * _particleRadius, MINIMUM_PARTICLE_RADIUS, MAXIMUM_PARTICLE_RADIUS);
_radiusFinishes[i] =
glm::clamp(spreadMultiplier * getRadiusFinish(), MINIMUM_PARTICLE_RADIUS, MAXIMUM_PARTICLE_RADIUS);
}
updateRadius(i, 0.0f);
// Position, velocity, and acceleration
if (_polarStart == 0.0f && _polarFinish == 0.0f && _emitDimensions.z == 0.0f) {
// Emit along z-axis from position
_particlePositions[i] = getPosition();
_particleVelocities[i] =
(_emitSpeed + randFloatInRange(-1.0f, 1.0f) * _speedSpread) * (_emitOrientation * Z_AXIS);
_particleAccelerations[i] = _emitAcceleration + randFloatInRange(-1.0f, 1.0f) * _accelerationSpread;
} else {
// Emit around point or from ellipsoid
// - Distribute directions evenly around point
// - Distribute points relatively evenly over ellipsoid surface
// - Distribute points relatively evenly within ellipsoid volume
float elevationMinZ = sin(PI_OVER_TWO - _polarFinish);
float elevationMaxZ = sin(PI_OVER_TWO - _polarStart);
float elevation = asin(elevationMinZ + (elevationMaxZ - elevationMinZ) * randFloat());
float azimuth;
if (_azimuthFinish >= _azimuthStart) {
azimuth = _azimuthStart + (_azimuthFinish - _azimuthStart) * randFloat();
} else {
azimuth = _azimuthStart + (TWO_PI + _azimuthFinish - _azimuthStart) * randFloat();
}
glm::vec3 emitDirection;
if (_emitDimensions == glm::vec3()) {
// Point
emitDirection = glm::quat(glm::vec3(PI_OVER_TWO - elevation, 0.0f, azimuth)) * Z_AXIS;
_particlePositions[i] = getPosition();
} else {
// Ellipsoid
float radiusScale = 1.0f;
if (_emitRadiusStart < 1.0f) {
float emitRadiusStart = glm::max(_emitRadiusStart, EPSILON); // Avoid math complications at center
float randRadius =
emitRadiusStart + randFloatInRange(0.0f, MAXIMUM_EMIT_RADIUS_START - emitRadiusStart);
radiusScale = 1.0f - std::pow(1.0f - randRadius, 3.0f);
}
glm::vec3 radiuses = radiusScale * 0.5f * _emitDimensions;
float x = radiuses.x * glm::cos(elevation) * glm::cos(azimuth);
float y = radiuses.y * glm::cos(elevation) * glm::sin(azimuth);
float z = radiuses.z * glm::sin(elevation);
glm::vec3 emitPosition = glm::vec3(x, y, z);
emitDirection = glm::normalize(glm::vec3(
radiuses.x > 0.0f ? x / (radiuses.x * radiuses.x) : 0.0f,
radiuses.y > 0.0f ? y / (radiuses.y * radiuses.y) : 0.0f,
radiuses.z > 0.0f ? z / (radiuses.z * radiuses.z) : 0.0f
));
_particlePositions[i] = getPosition() + _emitOrientation * emitPosition;
}
_particleVelocities[i] =
(_emitSpeed + randFloatInRange(-1.0f, 1.0f) * _speedSpread) * (_emitOrientation * emitDirection);
_particleAccelerations[i] = _emitAcceleration + randFloatInRange(-1.0f, 1.0f) * _accelerationSpread;
}
integrateParticle(i, timeLeftInFrame);
extendBounds(_particlePositions[i]);
// Color
if (_colorSpread == xColor{ 0, 0, 0 }) {
_colorStarts[i] = getColorStart();
_colorMiddles[i] = getXColor();
_colorFinishes[i] = getColorFinish();
} else {
xColor startColor = getColorStart();
xColor middleColor = getXColor();
xColor finishColor = getColorFinish();
float spread = randFloatInRange(-1.0f, 1.0f);
float spreadMultiplierRed =
middleColor.red > 0 ? 1.0f + spread * (float)_colorSpread.red / (float)middleColor.red : 1.0f;
float spreadMultiplierGreen =
middleColor.green > 0 ? 1.0f + spread * (float)_colorSpread.green / (float)middleColor.green : 1.0f;
float spreadMultiplierBlue =
middleColor.blue > 0 ? 1.0f + spread * (float)_colorSpread.blue / (float)middleColor.blue : 1.0f;
_colorStarts[i].red = (int)glm::clamp(spreadMultiplierRed * (float)startColor.red, 0.0f, 255.0f);
_colorStarts[i].green = (int)glm::clamp(spreadMultiplierGreen * (float)startColor.green, 0.0f, 255.0f);
_colorStarts[i].blue = (int)glm::clamp(spreadMultiplierBlue * (float)startColor.blue, 0.0f, 255.0f);
_colorMiddles[i].red = (int)glm::clamp(spreadMultiplierRed * (float)middleColor.red, 0.0f, 255.0f);
_colorMiddles[i].green = (int)glm::clamp(spreadMultiplierGreen * (float)middleColor.green, 0.0f, 255.0f);
_colorMiddles[i].blue = (int)glm::clamp(spreadMultiplierBlue * (float)middleColor.blue, 0.0f, 255.0f);
_colorFinishes[i].red = (int)glm::clamp(spreadMultiplierRed * (float)finishColor.red, 0.0f, 255.0f);
_colorFinishes[i].green = (int)glm::clamp(spreadMultiplierGreen * (float)finishColor.green, 0.0f, 255.0f);
_colorFinishes[i].blue = (int)glm::clamp(spreadMultiplierBlue * (float)finishColor.blue, 0.0f, 255.0f);
}
updateColor(i, 0.0f);
// Alpha
if (_alphaSpread == 0.0f) {
_alphaStarts[i] = getAlphaStart();
_alphaMiddles[i] = _alpha;
_alphaFinishes[i] = getAlphaFinish();
} else {
float spreadMultiplier = 1.0f + randFloatInRange(-1.0f, 1.0f) * _alphaSpread / _alpha;
_alphaStarts[i] = spreadMultiplier * getAlphaStart();
_alphaMiddles[i] = spreadMultiplier * _alpha;
_alphaFinishes[i] = spreadMultiplier * getAlphaFinish();
}
updateAlpha(i, 0.0f);
_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;
}
}
