/
RenderableParticleBunch.cpp
733 lines (571 loc) · 26.7 KB
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RenderableParticleBunch.cpp
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#include "RenderableParticleBunch.h"
#include "itextstream.h"
#include "math/pi.h"
#include "string/string.h"
namespace particles
{
RenderableParticleBunch::RenderableParticleBunch(std::size_t index,
Rand48::result_type randSeed, const IStageDef& stage, const Matrix4& viewRotation,
const Vector3& direction, const Vector3& entityColour) :
_index(index),
_stage(stage),
_quads(),
_randSeed(randSeed),
_distributeParticlesRandomly(_stage.getRandomDistribution()),
_offset(_stage.getOffset()),
_viewRotation(viewRotation),
_direction(direction),
_entityColour(entityColour)
{
// Geometry is written in update(), just reserve the space
}
void RenderableParticleBunch::update(std::size_t time)
{
_bounds = AABB();
_quads.clear();
// Length of one cycle (duration + deadtime)
std::size_t cycleMsec = static_cast<std::size_t>(_stage.getCycleMsec());
if (cycleMsec == 0)
{
return;
}
// Reserve enough space for all the particles (non-animated case)
_quads.reserve(_stage.getCount() * 4);
// Normalise the global input time into local cycle time
// The cycleTime may be larger than the _stage.cycleMsec argument if bunching is turned off
std::size_t cycleTime = time - cycleMsec * _index;
// Reset the random number generator using our stored seed
_random.seed(_randSeed);
// Calculate the time between each particle spawn
// When bunching is set to 1 the spacing is 0, and vice versa.
std::size_t stageDurationMsec = static_cast<std::size_t>(SEC2MS(_stage.getDuration()));
float spawnSpacing = _stage.getBunching() * static_cast<float>(stageDurationMsec) / _stage.getCount();
// This is the spacing between each particle
std::size_t spawnSpacingMsec = static_cast<std::size_t>(spawnSpacing);
// Generate all particle quads, regardless of their visibility
// Visibility is considered by not rendering particles that haven't been spawned yet
for (std::size_t i = 0; i < static_cast<std::size_t>(_stage.getCount()); ++i)
{
// Consider bunching parameter
std::size_t particleStartTimeMsec = i * spawnSpacingMsec;
if (cycleTime < particleStartTimeMsec)
{
// This particle is not visible at the given time
continue;
}
assert(particleStartTimeMsec < stageDurationMsec); // some sanity checks
// Get the "local particle time" in msecs
std::size_t particleTime = cycleTime - particleStartTimeMsec;
// Generate the particle renderinfo structure (our working set)
ParticleRenderInfo particle(i, _random);
// Calculate the time fraction [0..1]
particle.timeFraction = static_cast<float>(particleTime) / stageDurationMsec;
// We need the particle time in seconds for the location/angle integrations
particle.timeSecs = MS2SEC(particleTime);
// Calculate particle origin at time t
calculateOrigin(particle);
// Get the initial angle value
particle.angle = _stage.getInitialAngle();
if (particle.angle == 0)
{
// Use random angle
particle.angle = 360 * static_cast<float>(_random()) / _random.max();
}
// Past this point, no more "randomness" is required, so let's check if we still need
// to render this particular particle. Don't dismiss particles too early, as each of them
// will change the RNG state in the calculations above. These state changes are important for
// all the subsequent particles.
// Each particle has a lifetime of <stage duration> at maximum
if (particleTime > stageDurationMsec)
{
continue; // particle has expired
}
// Calculate the time-dependent angle
// according to docs, half the quads have negative rotation speed
int rotFactor = i % 2 == 0 ? -1 : 1;
particle.angle += rotFactor * integrate(_stage.getRotationSpeed(), particle.timeSecs);
// Calculate render colour for this particle
calculateColour(particle);
// Consider quad size
particle.size = _stage.getSize().evaluate(particle.timeFraction);
// Consider aspect ratio
particle.aspect = _stage.getAspect().evaluate(particle.timeFraction);
// Consider animation frames
particle.animFrames = static_cast<std::size_t>(_stage.getAnimationFrames());
if (particle.animFrames > 0)
{
// Calculate the s coordinates and the resulting particle colour
calculateAnim(particle);
}
// For aimed orientation, we need to override particle height and aspect
if (_stage.getOrientationType() == IStageDef::ORIENTATION_AIMED)
{
pushAimedParticles(particle, stageDurationMsec);
}
else
{
if (particle.animFrames > 0)
{
// Animated, push two crossfaded quads
pushQuad(particle, particle.curColour, particle.sWidth * particle.curFrame, particle.sWidth);
pushQuad(particle, particle.nextColour, particle.sWidth * particle.nextFrame, particle.sWidth);
}
else
{
// Non-animated quad
pushQuad(particle, particle.colour);
}
}
}
}
void RenderableParticleBunch::addVertexData(std::vector<MeshVertex>& vertices,
std::vector<unsigned int>& indices, const Matrix4& localToWorld)
{
if (_quads.empty()) return;
auto firstIndex = static_cast<unsigned int>(vertices.size());
auto quadIndex = 0;
for (const auto& quad : _quads)
{
for (auto i = 0; i < 4; ++i)
{
auto worldVertex = localToWorld * quad.verts[i].vertex;
vertices.push_back(MeshVertex(
worldVertex,
quad.verts[i].normal,
quad.verts[i].texcoord,
quad.verts[i].colour)
);
}
auto index = firstIndex + quadIndex * 4;
indices.push_back(index + 0);
indices.push_back(index + 1);
indices.push_back(index + 2);
indices.push_back(index + 0);
indices.push_back(index + 2);
indices.push_back(index + 3);
quadIndex++;
}
}
const AABB& RenderableParticleBunch::getBounds()
{
if (!_bounds.isValid())
{
calculateBounds();
}
return _bounds;
}
Matrix4 RenderableParticleBunch::getAimedMatrix(const Vector3& particleVelocity)
{
// Get the velocity direction in object space, use the same velocity for all trailing quads
Vector3 vel = particleVelocity.getNormalised();
// Construct the matrices
const Matrix4& camera2Object = _viewRotation;
// The matrix rotating the particle into velocity space
Matrix4 object2Vel = Matrix4::getRotation(Vector3(0,1,0), vel);
// Transform the view (-z) vector into object space
Vector3 view = camera2Object.transformPoint(Vector3(0,0,-1));
// Project the view vector onto the plane defined by the velocity vector
Vector3 viewProj = view - vel * view.dot(vel);
// This is the particle normal in object space (after being oriented such that y || velocity)
Vector3 z = object2Vel.zCol3();
// The particle needs to be rotated by this angle around the velocity axis
double aimedAngle = z.angle(-viewProj);
// Use the cross to check whether to rotate in negative or positive direction
if (z.cross(-viewProj).dot(vel) > 0)
{
aimedAngle *= -1;
}
// Calculate the rotation of the particle normal towards the view vector, around the velocity axis
Matrix4 vel2aimed = Matrix4::getRotation(vel, aimedAngle);
// Combine the matrices object2Vel => vel2aimed;
return vel2aimed.getMultipliedBy(object2Vel);
}
void RenderableParticleBunch::calculateAnim(ParticleRenderInfo& particle)
{
// At a given time, two particles can be visible at most
float frameRate = _stage.getAnimationRate();
// The time interval for cross-fading, fall back to entire duration * 3 for zero animation rates
float frameIntervalSecs = frameRate > 0 ? 1.0f / frameRate : 3 * _stage.getDuration();
// Calculate the current frame number, wrap around
particle.curFrame = static_cast<std::size_t>(floor(particle.timeSecs / frameIntervalSecs)) % particle.animFrames;
// Wrap next frame around animationFrame count for looping
particle.nextFrame = (particle.curFrame + 1) % particle.animFrames;
// Calculate the time within the frame, relative to frame start
float frameMicrotime = float_mod(particle.timeSecs, frameIntervalSecs);
// As a fading lasts as long as the entire interval, the alpha gradient is the same as the FPS value
// The "current" particle is always fading out, the nextFrame is fading in
float curAlpha = 1.0f - frameRate * frameMicrotime;
float nextAlpha = frameRate * frameMicrotime;
particle.curColour = particle.colour * curAlpha;
particle.nextColour = particle.colour * nextAlpha;
// The width of a single frame in texture space
particle.sWidth = 1.0f / particle.animFrames;
}
void RenderableParticleBunch::calculateColour(ParticleRenderInfo& particle)
{
Vector4 mainColour = !_stage.getUseEntityColour() ?
_stage.getColour() : Vector4(_entityColour.x(), _entityColour.y(), _entityColour.z(), 1);
// We start with the stage's standard colour
particle.colour = mainColour;
// Consider fade index fraction, which can spawn particles already faded to some extent
float fadeIndexFraction = _stage.getFadeIndexFraction();
if (fadeIndexFraction > 0)
{
// greebo: The linear fading function goes like this:
// frac(t) = (startFrac - t) / (startFrac - 1) with t in [0..1]
// Boundary conditions: frac(1) = 1 and frac(startFrac) = 0
// Use the particle index as "time", normalised to [0..1]
// such that particle with higher index start more faded
float pIdx = static_cast<float>(particle.index) / _stage.getCount();
// Calculate how much we should be faded already
float startFrac = 1.0f - fadeIndexFraction;
float frac = (startFrac - pIdx) / (startFrac - 1.0f);
// Ignore negative fraction values, this also takes care that only
// those particles with time >= fadeIndexFraction get faded.
if (frac > 0)
{
particle.colour = lerpColour(particle.colour, _stage.getFadeColour(), frac);
}
}
float fadeInFraction = _stage.getFadeInFraction();
if (fadeInFraction > 0 && particle.timeFraction <= fadeInFraction)
{
particle.colour = lerpColour(_stage.getFadeColour(), mainColour, particle.timeFraction / fadeInFraction);
}
float fadeOutFraction = _stage.getFadeOutFraction();
float fadeOutFractionInverse = 1.0f - fadeOutFraction;
if (fadeOutFraction > 0 && particle.timeFraction >= fadeOutFractionInverse)
{
particle.colour = lerpColour(mainColour, _stage.getFadeColour(), (particle.timeFraction - fadeOutFractionInverse) / fadeOutFraction);
}
}
void RenderableParticleBunch::calculateOrigin(ParticleRenderInfo& particle)
{
// Check if the main direction is different to the z axis
Vector3 dir = _direction.getNormalised();
Vector3 zDir(0,0,1);
double deviation = dir.angle(zDir);
Matrix4 rotation = deviation != 0 ? Matrix4::getRotation(zDir, dir) : Matrix4::getIdentity();
// Consider offset as starting point
particle.origin = rotation.transformPoint(_offset);
switch (_stage.getCustomPathType())
{
case IStageDef::PATH_STANDARD: // Standard path calculation
{
// Consider particle distribution
Vector3 distributionOffset = getDistributionOffset(particle, _distributeParticlesRandomly);
// Add this to the origin
particle.origin += distributionOffset;
// Calculate particle direction, pass distribution offset (this is needed for DIRECTION_OUTWARD)
Vector3 particleDirection = getDirection(particle, rotation, distributionOffset);
// Consider speed
particle.origin += particleDirection * integrate(_stage.getSpeed(), particle.timeSecs);
}
break;
case IStageDef::PATH_FLIES:
{
// greebo: "Flies" particles are moving on the surface of a sphere of radius <size>
// The radial and axial speeds are chosen at random (but never 0) and are constant
// during the lifetime of a particle. Starting position appears to be random,
// but different to the "distribution sphere" type (i.e. it is not evenly distributed,
// instead the particles seem to bunch themselves at the poles).
// Sphere radius
float radius = _stage.getCustomPathParm(2);
// Generate starting conditions speed (+/-50%)
float rand = 2 * particle.rand[0] - 1.0f;
float radialSpeedFactor = 1.0f + 0.5f * rand * rand;
// greebo: factor 0.4 is empirical, I measured a few D3 particles for their circulation times
float radialSpeed = _stage.getCustomPathParm(0) * radialSpeedFactor * 0.4f;
rand = 2 * particle.rand[1] - 1.0f;
float axialSpeedFactor = 1.0f + 0.5f * rand * rand;
float axialSpeed = _stage.getCustomPathParm(1) * axialSpeedFactor * 0.4f;
float phi0 = 2 * static_cast<float>(math::PI) * particle.rand[2];
float theta0 = static_cast<float>(math::PI) * particle.rand[3];
// Calculate angles at the given particleTime
float phi = phi0 + axialSpeed * particle.timeSecs;
float theta = theta0 + radialSpeed * particle.timeSecs;
// Pre-calculate the sin/cos values
float cosPhi = cos(phi);
float sinPhi = sin(phi);
float cosTheta = cos(theta);
float sinTheta = sin(theta);
// Move the particle origin
particle.origin += Vector3(radius * cosTheta * sinPhi, radius * sinTheta * sinPhi, radius * cosPhi);
}
break;
case IStageDef::PATH_HELIX:
{
// greebo: Helical movement is describing an elliptic cylinder, its shape is determined by
// sizeX, sizeY and sizeZ. Particles are spawned randomly on that cylinder surface,
// their velocities (radial and axial) are also random (both negative and positive
// velocities are allowed).
float sizeX = _stage.getCustomPathParm(0);
float sizeY = _stage.getCustomPathParm(1);
float sizeZ = _stage.getCustomPathParm(2);
float radialSpeed = _stage.getCustomPathParm(3) * (2 * particle.rand[0] - 1.0f);
float axialSpeed = _stage.getCustomPathParm(4) * (2 * particle.rand[1] - 1.0f);
float phi0 = 2 * static_cast<float>(math::PI) * particle.rand[2];
float z0 = sizeZ * (2 * particle.rand[3] - 1.0f);
float sinPhi = sin(phi0 + radialSpeed * particle.timeSecs);
float cosPhi = cos(phi0 + radialSpeed * particle.timeSecs);
float x = sizeX * cosPhi;
float y = sizeY * sinPhi;
float z = z0 + axialSpeed * particle.timeSecs;
particle.origin += Vector3(x, y, z);
}
break;
case IStageDef::PATH_ORBIT:
case IStageDef::PATH_DRIP:
// These are actually unsupported by the engine ("bad path type")
rWarning() << "Unsupported path type (drip/orbit)." << std::endl;
break;
default:
// Nothing
break;
};
// Consider gravity
// if "world" is set, use -z as gravity direction, otherwise use the reverse emitter direction
Vector3 gravity = _stage.getWorldGravityFlag() ? Vector3(0,0,-1) : -_direction.getNormalised();
particle.origin += gravity * _stage.getGravity() * particle.timeSecs * particle.timeSecs * 0.5f;
}
Vector3 RenderableParticleBunch::getDirection(ParticleRenderInfo& particle, const Matrix4& rotation, const Vector3& distributionOffset)
{
switch (_stage.getDirectionType())
{
case IStageDef::DIRECTION_CONE:
{
// Find a random vector on the sphere surface defined by the cone with apex 2*angle
float u = particle.rand[3];
// Scale the variable v such that it takes uniform values in the interval [(1+cos(angle))/2 .. 1]
float angleRad = _stage.getDirectionParm(0) * static_cast<float>(math::PI) / 180.0f;
float v0 = (1 + cos(angleRad)) * 0.5f;
float v1 = 1;
float v = v0 + particle.rand[4] * (v1 - v0);
float theta = 2 * static_cast<float>(math::PI) * u;
float phi = acos(2*v - 1);
Vector3 endPoint(cos(theta) * sin(phi), sin(theta) * sin(phi), cos(phi));
// Rotate the vector into the particle's main direction
endPoint = rotation.transformPoint(endPoint);
return endPoint.getNormalised();
}
case IStageDef::DIRECTION_OUTWARD:
{
// This heavily relies on particles being distributed randomly within the spawn area
Vector3 direction = distributionOffset.getNormalised();
// Consider upwards bias
direction.z() += _stage.getDirectionParm(0);
return direction; // CHECKME: Use .getNormalised() ?
}
default:
return Vector3(0,0,1);
};
}
Vector3 RenderableParticleBunch::getDistributionOffset(ParticleRenderInfo& particle, bool distributeParticlesRandomly)
{
switch (_stage.getDistributionType())
{
// Rectangular distribution
case IStageDef::DISTRIBUTION_RECT:
{
// Factors to use for the random distribution
float randX = 1.0f;
float randY = 1.0f;
float randZ = 1.0f;
if (distributeParticlesRandomly)
{
// Rectangular spawn zone
randX = 2 * particle.rand[0] - 1.0f;
randY = 2 * particle.rand[1] - 1.0f;
randZ = 2 * particle.rand[2] - 1.0f;
}
// If random distribution is off, particles get spawned at <sizex, sizey, sizez>
return Vector3(randX * _stage.getDistributionParm(0),
randY * _stage.getDistributionParm(1),
randZ * _stage.getDistributionParm(2));
}
case IStageDef::DISTRIBUTION_CYLINDER:
{
// Get the cylinder dimensions
float sizeX = _stage.getDistributionParm(0);
float sizeY = _stage.getDistributionParm(1);
float sizeZ = _stage.getDistributionParm(2);
float ringFrac = _stage.getDistributionParm(3);
// greebo: Some tests showed that for the cylinder type
// the fourth parameter ("ringfraction") is only effective if >1,
// it effectively scales the elliptic shape by that factor.
// Values < 1.0 didn't have any effect (?) Someone could double-check that.
// Interestingly, the built-in particle editor doesn't really allow editing that parameter.
if (ringFrac > 1.0f)
{
sizeX *= ringFrac;
sizeY *= ringFrac;
}
if (distributeParticlesRandomly)
{
// Get a random angle in [0..2pi]
float angle = static_cast<float>(2*math::PI) * particle.rand[0];
float xPos = cos(angle) * sizeX;
float yPos = sin(angle) * sizeY;
float zPos = sizeZ * (2 * particle.rand[1] - 1.0f);
return Vector3(xPos, yPos, zPos);
}
else
{
// Random distribution is off, particles get spawned at <sizex, sizey, sizez>
return Vector3(sizeX, sizeY, sizeZ);
}
}
case IStageDef::DISTRIBUTION_SPHERE:
{
// Get the sphere dimensions
float maxX = _stage.getDistributionParm(0);
float maxY = _stage.getDistributionParm(1);
float maxZ = _stage.getDistributionParm(2);
float ringFrac = _stage.getDistributionParm(3);
float minX = maxX * ringFrac;
float minY = maxY * ringFrac;
float minZ = maxZ * ringFrac;
if (distributeParticlesRandomly)
{
// The following is modeled after http://mathworld.wolfram.com/SpherePointPicking.html
float u = particle.rand[0];
float v = particle.rand[1];
float theta = 2 * static_cast<float>(math::PI) * u;
float phi = acos(2*v - 1);
// Take the sqrt(radius) to correct bunching at the center of the sphere
float r = sqrt(particle.rand[2]);
float x = (minX + (maxX - minX) * r) * cos(theta) * sin(phi);
float y = (minY + (maxY - minY) * r) * sin(theta) * sin(phi);
float z = (minZ + (maxZ - minZ) * r) * cos(phi);
return Vector3(x,y,z);
}
else
{
// Random distribution is off, particles get spawned at <sizex, sizey, sizez>
return Vector3(maxX, maxY, maxZ);
}
}
// Default case, should not be reachable
default:
return Vector3(0,0,0);
};
}
void RenderableParticleBunch::pushQuad(ParticleRenderInfo& particle, const Vector4& colour, float s0, float sWidth)
{
// greebo: Create a (rotated) quad facing the z axis
// then rotate it to fit the requested orientation
// finally translate it to its position.
const Vector3 normal = _viewRotation.zCol3();
_quads.push_back(ParticleQuad(particle.size, particle.aspect, particle.angle, colour, normal, s0, sWidth));
_quads.back().transform(_viewRotation);
_quads.back().translate(particle.origin);
}
void RenderableParticleBunch::pushAimedParticles(ParticleRenderInfo& particle, std::size_t stageDurationMsec)
{
int trails = static_cast<int>(_stage.getOrientationParm(0)); // trails
float aimedTime = _stage.getOrientationParm(1); // time
if (trails < 0)
{
trails = 0;
}
// The time parameter defaults to 0.5 if not specified
if (aimedTime == 0.0f)
{
aimedTime = 0.5f;
}
// The time delta to step into the past
int numQuads = trails + 1;
// The time delta between quads
float timeStep = aimedTime / numQuads;
Vector3 lastOrigin = particle.origin;
for (int i = 1; i <= numQuads; ++i)
{
// Copy over the info of the incoming particle (contains anim info, colour, etc.)
ParticleRenderInfo aimedParticle = particle;
// Get the time of the i-th particle in seconds, plus the fraction
aimedParticle.timeSecs = particle.timeSecs - timeStep * i;
aimedParticle.timeFraction = SEC2MS(aimedParticle.timeSecs) / stageDurationMsec;
// Get origin and velocity at that time
calculateOrigin(aimedParticle);
// Gotcha: don't bother calculating the actual velocity at the given time, just use the
// difference vector of the two origins, this is enough to receive the "aimed" direction
Vector3 velocity = lastOrigin - aimedParticle.origin;
float height = static_cast<float>(velocity.getLength());
aimedParticle.aspect = height / (2 * aimedParticle.size);
// Calculate the vertical texture coordinates
aimedParticle.tWidth = 1.0f / static_cast<float>(numQuads);
aimedParticle.t0 = (i - 1) * aimedParticle.tWidth;
// The matrix is special for each particle. For helix and other path types
// it's necessary to apply the same matrix to each vertex sharing the same 3D location.
// Calculate the matrix to orient it towards the viewer
Matrix4 local2aimed = getAimedMatrix(velocity);
{
const Vector3 normal = local2aimed.zCol3();
// Ignore the angle for aimed orientation
ParticleQuad curQuad(aimedParticle.size, aimedParticle.aspect, 0,
aimedParticle.colour, normal, 0, 1, aimedParticle.t0, aimedParticle.tWidth);
// Apply a slight origin correction before rotating them, particles are not centered around 0,0,0 here
curQuad.translate(Vector3(0, -height*0.5f, 0));
curQuad.transform(local2aimed);
curQuad.translate(lastOrigin);
// Push two quads for animated particles
if (aimedParticle.animFrames > 0)
{
// "Current" quad
curQuad.assignColour(aimedParticle.curColour);
// Set the hoirzontal texcoord for the current frame
curQuad.setHorizTexCoords(aimedParticle.sWidth * aimedParticle.curFrame, aimedParticle.sWidth);
// Glue the first row of vertices to the last quad, if applicable
if (i > 1)
{
snapQuads(curQuad, *(_quads.end()-2));
}
_quads.push_back(curQuad);
// "Next" quad, re-use the curQuad structure
curQuad.assignColour(aimedParticle.nextColour);
// Set the hoirzontal texcoord for the next frame
curQuad.setHorizTexCoords(aimedParticle.sWidth * aimedParticle.nextFrame, aimedParticle.sWidth);
if (i > 1)
{
snapQuads(curQuad, *(_quads.end()-2));
}
_quads.push_back(curQuad);
}
else
{
if (i > 1)
{
snapQuads(curQuad, _quads.back());
}
// Non-animated case
_quads.push_back(curQuad);
}
}
lastOrigin = aimedParticle.origin;
}
}
void RenderableParticleBunch::snapQuads(ParticleQuad& curQuad, ParticleQuad& prevQuad)
{
// Take the midpoint
curQuad.verts[0].vertex = (curQuad.verts[0].vertex + prevQuad.verts[3].vertex) * 0.5f;
curQuad.verts[1].vertex = (curQuad.verts[1].vertex + prevQuad.verts[2].vertex) * 0.5f;
// Snap the "previous" vertices to the same spot
prevQuad.verts[3].vertex = curQuad.verts[0].vertex;
prevQuad.verts[2].vertex = curQuad.verts[1].vertex;
// Interpolate the normals too
curQuad.verts[0].normal = (curQuad.verts[0].normal + prevQuad.verts[3].normal).getNormalised();
curQuad.verts[1].normal = (curQuad.verts[1].normal + prevQuad.verts[2].normal).getNormalised();
prevQuad.verts[3].normal = curQuad.verts[0].normal;
prevQuad.verts[2].normal = curQuad.verts[1].normal;
}
void RenderableParticleBunch::calculateBounds()
{
for (Quads::const_iterator i = _quads.begin(); i != _quads.end(); ++i)
{
_bounds.includePoint(i->verts[0].vertex);
_bounds.includePoint(i->verts[1].vertex);
_bounds.includePoint(i->verts[2].vertex);
_bounds.includePoint(i->verts[3].vertex);
}
}
} // namespace