MaxwellParticles

Description

This extension enables maxwell to render particles as spheres. These particles can be stored in a .bin or .pxy file, typically saved from realflow, or passed as internal data which is stored in the .mxs file.

Besides generating its own geometry, this extension can generate also its own UV coordinates. This is done using one or more of the 39 custom UV generators available. Each particle is assigned a pair of UV coordinates whose value depends on the generator used and the mapped magnitude. To use one of the generators, create a UV channel and assign it the desired custom type, and don't forget to enable loading the appropriate data array.

Example of how to create a MaxwellParticles object, add a uv channel, set its custom type to "Density" and enable loading the particle densities array.

CextensionManager* extensionManager = CextensionManager::instance();
CgeometryProceduralExtension* geomProcExtension = extensionManager->createGeometryProceduralExtension( "MaxwellParticles" );
//Get the extension container. When using this method of getting the container,
//nearly all parameters have default values, and there is no need to explicitly set them.
MXparamList* particlesParams = geomProcExtension->getExtensionData();

//Fill the required data
char* filename = "/home/rocco/Emitter01_00023.bin";
particlesParams->setString( "FileName", filename );

//Enable loading particle densities data
byte load = 1;
particlesParams->setByte( "Load particle Density", load );

//These two numbers can be obtained parsing the particles file
//They're needed to map the values of densities from 0.0 to 1.0 to access the texture.
float minD = 0.19;
float maxD = 1.67;
particlesParams->setFloat( "Min Density", minD );
particlesParams->setFloat( "Max Density", maxD );

//Get the number of custom generators available
byte numCustomUVGenerators = geomProcPlugin->getNumberOfUVGenerators();
Cmaxwell::Cobject obj = scene->createGeometryProceduralObject( "My Particles", particlesParams );

dword uvIndex;//returned uv channel index. Use this index in the texture map properties to access its uv's
byte isOk = obj.addChannelUVW( uvIndex );
obj.generateCustomUVW( uvIndex, 34 );//34 is the type of the custom uv generator.

//Now assign a material and set the first BSDF reflectance0º color a texture driven by uv channel 'uvIndex'
 

Parameters

UV Generators

"FileName"

Name of the file that contains particles data. It is a NULL terminated string.

Example:

char* file = "/home/paco/Emitter01_00049.bin"; 
extParam->setString( "FileName", file ); 

"Radius Factor"

Multiplier for the particle radius that is read from the file. Can go from 0.00001 to 1000000 and the default value is 1.

Example:

float rFactor = 0.3f; 
extParam->setFloat( "Radius Factor", rFactor );

"MB Factor"

Multiplier to increase or decrease the amount of motion blur of the particles. Can go from 0.0 to 1000000.0. Default is 1.0.

Example:

float factor = 0.3f; 
extParam->setFloat( "MB Factor", factor );

"Shutter 1/"

Shutterspeed of the active camera. Affects the amount of motion of the particles. It is the inverse of the time the shutter is open.

Example:

float shutter = 125.f;
extParam->setFloat( "Shutter 1/", shutter );

"Load particles %"

Percentage of particles to load. Can go from 0.0 to 100.0, default value is 100.

Example:

float percent = 75.f; 
extParam->setFloat( "Load particles %", percent );

"Create N particles per particle"

This parameter, if set greater than zero, activates the Multipoint feature, creating N more particles around each particle. So, if you have 100 particles and set this parameter to 4, it will create 400 more particles, and the final count will be 500.

Example:

unsigned int nParts = 10;
extParam->setUInt( "Create N particles per particle", nParts );

"Extra particles dispersion"

This parameter sets the size of the cloud of extra particles around each original particle. Can go from 0 to 100000. Default is 0.

Example:

float dispersion = 2.f;
extParam->setFloat( "Extra particles dispersion", dispersion );

"Extra particles deformation"

Sets the amount of deformation of the new particles cloud along the speed vector of the original particle. Can go from 0 to 100000. Default is 0.

Example:

float deformation = 1.1f;
extParam->setFloat( "Extra particles deformation", deformation );

"Load particle Force" "Load particle Vorticity" "Load particle Normal" "Load particle neighbors no." "Load particle UV" "Load particle Age" "Load particle Isolation Time" "Load particle Viscosity" "Load particle Density" "Load particle Pressure"  "Load particle Mass" "Load particle Temperature" "Load particle ID"

These flags enable the extension to load the magnitudes arrays to be used with the corresponding UV generators. Note that loading every array without later using it with the UV generator is a waste of memory and could slow the render process. Use them only if you need them.

The particle ID array is needed only if the Multipoint feature is used.

byte loadArray = 1;
extParam->setByte( "Load particle Viscosity", loadArray );

"Min Force" "Max Force" "Min Vorticity" "Max Vorticity" "Min Nneighbors" "Max Nneighbors" "Min Age" "Max Age" "Min Isolation Time" "Max Isolation Time" "Min Viscosity" "Max Viscosity" "Min Density" "Max Density" "Min Pressure" "Max Pressure" "Min Mass" "Max Mass" "Min Temperature" "Max Temperature"

These values must be set to normalize the values read from the corresponding magnitudes arrays. For vector magnitudes the max and min values should be the max and min modulus of these vectors.

"PARTICLE_POSITIONS"

Particle data can come whether in a file or internally stored in the .mxs file. If a filename is not supplied, the extension checks for internal data, and if successful, loads it. This parameter is a linear array of floats x0 y0 z0 x1 y1 z1 x2 y2 z2 x3 y3 z3 x4 y4 z4 ...., its length is 3*numberOfParticles.

Example:

int numParticles = 4;
float points[ 3*4 ];
for( int idx = 0; idx < numParticles; idx++ )
{
	points[ 3*idx + 0 ] = (float)idx;
	points[ 3*idx + 1 ] = (float)idx;
	points[ 3*idx + 2 ] = (float)idx;
}
extParam->setFloatArray( "PARTICLE_POSITIONS", points, 3*numParticles );

"PARTICLE_SPEEDS"

Linear array of particle speeds, floating point numbers, needed to enable calculation of motion blur: Vx0 Vy0 Vz0 Vx1 Vy1 Vz1 Vx2 Vy2 Vz2...., its length is 3*numberOfParticles.

Example:

int numParticles = 4;
float speeds[ 3*4 ];
for( int idx = 0; idx < numParticles; idx++ )
{
 speeds[ 3*idx + 0 ] = (float)idx;
 speeds[ 3*idx + 1 ] = (float)idx;
 speeds[ 3*idx + 2 ] = (float)idx;
}
extParam->setFloatArray( "PARTICLE_SPEEDS", speeds, 3*numParticles );

"PARTICLE_RADII"

Linear array of particle radii, floating point numbers: r0 r1 r2 r3 r4 r5 r6 .... The length of this array can be either 1 or numParticles. If only one radius is given , it is applied to all the particles, otherwise each particle gets its own radius.

Example:

//Each particle its own radius
int numParticles = 4;
float radius[ 4 ];
for( int idx = 0; idx < numParticles; idx++ )
{
 radius[ idx ] = (float)idx + 0.01f;
}
extParam->setFloatArray( "PARTICLE_RADII", radius, numParticles );

//One radius for all particles
float r = 0.4f;
setFloatArray( "PARTICLE_RADII", &r, 1 );

"PARTICLE_IDS"

Linear array of particle IDs, id0 id1 id2 id3 id4 id5.......needed to enable coherent calculation of multipoint. It is an integer array.

Example:

int numParticles = 3;
int ids[ 3 ];
ids[ 0 ] = 23;
ids[ 1 ] = 9;
ids[ 2 ] = 51;

extParam->setIntArray( "PARTICLE_IDS", ids, numParticles );