void Update()
{
Vector3 gridOrigin = new Vector3(-0.5f *gridScale * particle_Cel_Dim, 0f, 0f);
// reset array
// ParticleCels = new particle_cel[Particle_Cel_Dim, Particle_Cel_Dim];
for (int y = 0; y < particle_Cel_Dim; ++y)
{
for (int x = 0; x < particle_Cel_Dim; ++x)
{
ParticleCels[y, x].Density = 0;
//ParticleCels[y, x].VelocityTimesDensity = Vector3.zero;
/*
// borders test
if (x==0 || y==0 || x==Particle_Cel_Dim-1 || y==Particle_Cel_Dim-1)
{
ParticleCels[y, x].Density = 1;
}else{
ParticleCels[y, x].Density = 0;
}*/
/*
// update obstacle maps test
for (int i = 0; i < obstacles.Length; i++)
{
float distance = (new Vector3(x,y,0)-(obstacles[i].position-GridOrigin)*InvGridScale).sqrMagnitude*2f;
if (distance>Particle_Cel_Dim) distance=Particle_Cel_Dim;
ParticleCels[y, x].Density += Mathf.Clamp((Particle_Cel_Dim-distance),0,Particle_Cel_Dim);
}
// test perlin map
ParticleCels[y, x].Density = Mathf.PerlinNoise(2.2f+x*0.06f,2.2f+y*0.06f);
if (ParticleCels[y, x].Density<0.4f) ParticleCels[y, x].Density=0;
if (ParticleCels[y, x].Density>0.4f) ParticleCels[y, x].Density*=9999f;
*/
}
}
// (re)spawn particle
for (int particleSpawnIndex = 0; particleSpawnIndex < spawnRate; ++particleSpawnIndex)
{
NextParticle=(NextParticle+1) % particlesAmount;
// set initial values
particles[NextParticle].P = transform.position+new Vector3(Random.Range(-0.05f, 0.05f), Random.Range(-0.05f, 0.05f), 0); // start position
// particles[NextParticle].dP = new Vector3(Random.Range(-0.07f,0.07f),0.85f,0)*7; // start speed, global direction
particles[NextParticle].dP = transform.TransformDirection(new Vector3(Random.Range(-0.01f,0.01f),7f*Random.Range(0.98f,1f),0f)); // start speed in local transform direction
particles[NextParticle].ddP = new Vector3(0f, -9.81f, 0f); // gravity
particles[NextParticle].Col = initialColor;
float randomVal = Random.Range(-0.25f, -1f);
particles[NextParticle].dColor = new Vector4(0,0,0,randomVal); // deltaColor
sprites[NextParticle].transform.position = Vector3.zero;
sprites[NextParticle].transform.localScale = Vector3.one;
}
// map particles to grid & add cell density
for (int particleIndex = 0; particleIndex < particles.Length; ++particleIndex)
{
Vector3 P = InvGridScale * (particles[particleIndex].P - gridOrigin);
int X = (int)P.x;
int Y = (int)P.y;
if (X < 0) X = 0;
if (X > particle_Cel_Dim-1) X = particle_Cel_Dim-1;
if (Y < 0) Y = 0;
if (Y > particle_Cel_Dim - 1) Y = particle_Cel_Dim - 1;
float densityFromAlpha = particles[particleIndex].Col.w;
ParticleCels[Y, X].Density += densityFromAlpha;
ParticleCels[Y, X].VelocityTimesDensity += densityFromAlpha*particles[particleIndex].dP;
}
if (debugMode)
{
// draw preview grid
for (int y = 0; y < particle_Cel_Dim; ++y)
{
for (int x = 0; x < particle_Cel_Dim; ++x)
{
float alpha = Clamp01(0.1f*ParticleCels[y, x].Density);
Color cellColor = new Color(alpha,alpha,alpha,1);
Vector3 gridPos = gridScale*new Vector3(x, y, 0f) + gridOrigin;
Debug.DrawLine(gridPos,gridPos+new Vector3(1,0,0)*gridScale,cellColor);
Debug.DrawLine(gridPos, gridPos + new Vector3(0, 1, 0)*gridScale, cellColor);
}
}
}
// simulate
for (int particleIndex = 0; particleIndex < particles.Length; ++particleIndex)
{
// snap to grid
Vector3 P = InvGridScale * (particles[particleIndex].P - gridOrigin);
int X = (int)P.x;
int Y = (int)P.y;
// clamp to edges
if (X < 1) X = 1;
if (X > particle_Cel_Dim-2) X = particle_Cel_Dim-2;
if (Y < 1) Y = 1;
if (Y > particle_Cel_Dim - 2) Y = particle_Cel_Dim - 2;
// get neighbour cell values
float celCenterDensity = ParticleCels[Y, X].Density;
float celLeftDensity = ParticleCels[Y, X-1].Density;
float celRightDensity = ParticleCels[Y, X+1].Density;
float celDownDensity = ParticleCels[Y-1, X].Density;
float celUpDensity = ParticleCels[Y+1, X].Density;
// calculate direction from cell density
Vector3 dispersion = Vector3.zero;
float dispersionCoeffifient = 0.5f; // multiplier of pushing force
/* original dispersion
dispersion += dispersionCoeffifient*(celCenterDensity-celLeftDensity)*new Vector3(-1f,0f,0f);
dispersion += dispersionCoeffifient*(celCenterDensity-celRightDensity)*new Vector3(1f,0f,0f);
dispersion += dispersionCoeffifient*(celCenterDensity-celDownDensity)*new Vector3(0f,-1f,0f);
dispersion += dispersionCoeffifient*(celCenterDensity-celUpDensity)*new Vector3(0f,1f,0f);
*/
// check which side the particle is more (left or right from particle system x)
float centerDistanceX = (particles[particleIndex].P.x-transform.position.x);
dispersion += dispersionCoeffifient*(celCenterDensity-celLeftDensity)*new Vector3(-1f+centerDistanceX,0f,0f);
dispersion += dispersionCoeffifient*(celCenterDensity-celRightDensity)*new Vector3(1f+centerDistanceX,0f,0f);
dispersion += dispersionCoeffifient*(celCenterDensity-celDownDensity)*new Vector3(0f,-1f,0f);
dispersion += dispersionCoeffifient*(celCenterDensity-celUpDensity)*new Vector3(0f,1f,0f);
Vector3 ddP = particles[particleIndex].ddP+(enableDispersion?dispersion:Vector3.zero);
// debug test
// if (particleIndex<1) Debug.Log(particles[particleIndex].dP);
// calculate movement & color
particles[particleIndex].P += (0.5f*Mathf.Sqrt(Time.deltaTime)*Time.deltaTime*ddP + Time.deltaTime*particles[particleIndex].dP);
particles[particleIndex].dP += Time.deltaTime*ddP;
particles[particleIndex].Col += Time.deltaTime*particles[particleIndex].dColor;
// ground collision & bounce
if (groundPlaneCollision && particles[particleIndex].P.y<groundY)
{
float coefficientOfRestitution = 0.3f;
float coefficientOfFriction = 0.7f;
particles[particleIndex].P.y = -particles[particleIndex].P.y;
particles[particleIndex].dP.y = -coefficientOfRestitution*particles[particleIndex].dP.y;
particles[particleIndex].dP.x = coefficientOfFriction*particles[particleIndex].dP.x;
}
/*
// TEST max speed clamp
if (particles[ParticleIndex].dP.sqrMagnitude>maxSpeed)
{
particles[ParticleIndex].dP = particles[ParticleIndex].dP.normalized*maxSpeed;
}*/
// clamp colors
particles[particleIndex].Col.x = Clamp01(particles[particleIndex].Col.x);
particles[particleIndex].Col.y = Clamp01(particles[particleIndex].Col.y);
particles[particleIndex].Col.z = Clamp01(particles[particleIndex].Col.z);
particles[particleIndex].Col.w = Clamp01(particles[particleIndex].Col.w);
// fix particle sudden spawn by making it transparent first, not working smoothly
if (particles[particleIndex].Col.w>0.9f)
{
particles[particleIndex].Col.w = 0.9f*Clamp01MapToRange(1f,(particles[particleIndex].Col.w),0.9f);
}
// set position, color, scale
sprites[particleIndex].transform.position = particles[particleIndex].P;
sprites[particleIndex].color = (Color)particles[particleIndex].Col;
var scaler = particles[particleIndex].Col.w;
sprites[particleIndex].transform.localScale = new Vector3(scaler, scaler, scaler)*0.75f; // scale test
}
}
