Indoor grafitti

An animation concept I am working on. Work in Progress.

indoor grafitti from Petfactory on Vimeo.

Burning fuel streak in Maya

Some short notes on setting up a burning fuel streak in Maya using fluids.

First I create a 2D container and set the density and velocity to static. Set temp, fuel and color to dynamic. Then I paint the density and fuel. I add an emitter to ignite the fuel. I only emit heat.

Some notes on controlling the burning flame.

Temperature:

Dissipation: Controls the “drop off” of the heat. How fast the temperature cools down. Larger value will produce a short tail, lower gives a longer tail ( it takes longer for the temp to cool down)

Diffusion: We need a low number of diffusion to make the simulation run, but for aesthetic reasons we want to keep this value quite low. High values will produce a blurred result or diffused really :)

Fuel

Heat Released: The heat that is released. Higher value will produce a stronger burn.

Controlling particles with expressions

It´s been awhile since I played around with expressions and particles. I recently saw a video where a softbody was controlled with a fluid. The idea is to use the velocity of each voxel of the fluid to position the particles of the softbody. I want to recreate this setup and the first step is to learn how to position particles. I did some initial test with some expressions.

if (pPlane1ParticleShape.particleId == 0)
{

vector $pos = pPlane1ParticleShape.position;
pPlane1ParticleShape.position = <<$pos.x,$pos.y+2,$pos.z>>;

}

if (pPlane1ParticleShape.particleId == 3)
{

vector $pos = pPlane1ParticleShape.position;
pPlane1ParticleShape.position = <<$pos.x,2,$pos.z>>;

}

if (pPlane1ParticleShape.particleId == 12)
{

vector $pos = pPlane1ParticleShape.position;
pPlane1ParticleShape.position = <<$pos.x, frame,$pos.z>>;

}

Maya : nParticles

Using emission rates pp

To control from which verts particles arte emitted we can use pp emission rates.

Using per particle expressions on nParticles

Using pp exp is the smae as using on the old particle type. if you use the exp below to kill off particles below a certain y value make sure to turn on use pp in the lifespan attribute of the particleShape.

vector $pos = nParticleShape1.position;
if ($pos.y < -2) nParticleShape1.lifespanPP = 0;

Emitting nParticles from nPartciles

If you want to emit nParticles from other nParticles it is just to select thenParticles and then emit from object. This will push the source emitting nParticles forward by the collision of the emitted particles. To turn this behaviour off disable the collisions of the source (the emitting ) particle.

If forcefiled generation is turned on of the emitted particles tey will also propell the source emitting particle.

To make nParticles not collide with nCloth

To make an nParticle just pass through an nCloth set the collision layer of the nParticle to something greater then the collision layer of the nucleus.

For instance the default collision layer range of a nucleus is 4 ( Nucleus>solver attributes>collision layer range). if we set the collision layer of the nCloth ( nClothShape>collisions>collision layer) to something greater then the collision layer range of the nucleus, they will not collide.

Maya : Fluids

Maya fluid note to self

Emitting nParticles from nPartciles

If you want to emit nParticles from other nParticles it is just to select thenParticles and then emit from object. This will push the source emitting nParticles forward by the collision of the emitted particles. To turn this behaviour off disable the collisions of the source (the emitting ) particle.

If forcefiled generation is turned on of the emitted particles tey will also propell the source emitting particle.

To make nParticles not collide with nCloth

To make an nParticle just pass through an nCloth set the collision layer of the nParticle to something greater then the collision layer of the nucleus.

For instance the default collision layer range of a nucleus is 4 ( Nucleus>solver attributes>collision layer range). if we set the collision layer of the nCloth ( nClothShape>collisions>collision layer) to something greater then the collision layer range of the nucleus, they will not collide.

For a puff of smoke or dust effect (at the footsteps of a character, for example)

• key fluidEmitter > Fluid Attributes > Density/Voxel/Sec
• and maybe > Heat/Voxel/Sec to 0, then 20 for a few frames, then 0 again.

Set color of emitted fluid & blend colors

• seledct the container contents method > color method set it to dynamic grid
• To set the color of fluid select the emitter > Fluid attributes > enable emit fluid color and then select the color tou want.
• add more emitters, set the color and the color are blended togheter.

To render a 2d fluid as a displaced surface

• create a 2d fluid and emitter
• enable use heightfield
• set the depth to a higher value
• shading > set the transparency to 0
• shading > color > create a bw gradient
• shading > set the color input to density