MeshEmitter         A plugin mesh emitter where by each vertex in the the mesh is treated as an emitter

This plugin makes use of "Retrieving vertex data from a mesh" function and credit should be given to all those involved in its creation.

WARNING: This code has not been subjected to vigorous testing and as such it may not operatate as expected. Use with caution.

CLEAN ME

Anyone is welcome to clean up this code.

Usage

Create factory.

bool MyApplication::setup( void ) {
    mRoot = new Root();

        // MeshEmitter
        pMeshEmitFact = new MeshEmitterFactory();
        ParticleSystemManager::getSingleton().addEmitterFactory(pMeshEmitFact);

    .
    .
    .


The mesh emitters take 4 additional parameters.

mesh - String value.

File name of the mesh to be used.

random - Boolean value.
default: true

If true the particles are emitted from random vertices otherwise the vertices are used sequentially.

coverage - Real value between 0 and 1.

default: 0.0

The coverage dictates the percentage of vertices that will emit simultaneously.
i.e with a value 0.5 half the vertices emit simultaneously.
A coverage of 0 will result in one vertex emitting in turn.

use_vertex_normals - Boolean value.

default: true

Vertex normal is used to particles initial direction.

Example Emitter

An edited version of GreenyNimbus to use the ogrehead mesh as the emitter.

// Exudes greeny particles which float upwards
Examples/GreenyNimbus
{
    material        Examples/Flare
    particle_width  5
    particle_height 5
    cull_each       false
    quota           5000
    billboard_type  point
    
    // Area emitter
    emitter Mesh
    {
        angle           30
        emission_rate   50
        time_to_live    5
        direction       0 1 0
        velocity        7
        colour_range_start  1 1 0
        colour_range_end    0.3 1 0.3
        mesh        ogrehead.mesh
    random        false
    coverage    1.00
    use_vertex_normals    false
    }

    // Make em float upwards
    affector LinearForce
    {
        force_vector      0 6 0
        force_application add
    }

    // Fader
    affector ColourFader
    {
        red -0.25
        green -0.25
        blue -0.25
    }

}

MeshEmitter

MeshEmitter.h

#ifndef __MeshEmitter_H__
#define __MeshEmitter_H__

#include "OgreParticleFXPrerequisites.h"
#include "OgreParticleEmitter.h"
#include "OgreMesh.h"

namespace Ogre {

    class _OgreParticleFXExport MeshEmitter : public ParticleEmitter
    {
    public:
        /** Command object for random emitters (see ParamCommand).*/
        class CmdRandom : public ParamCommand
        {
        public:
            String doGet(const void* target) const;
            void doSet(void* target, const String& val);
        };
        /** Command object for percentage coverage emitters (see ParamCommand).*/
        class CmdCoverage : public ParamCommand
        {
        public:
            String doGet(const void* target) const;
            void doSet(void* target, const String& val);
        };
        /** Command object for using vertex normal directions (see ParamCommand).*/
        class CmdUseVertexNormals : public ParamCommand
        {
        public:
            String doGet(const void* target) const;
            void doSet(void* target, const String& val);
        };
        /** Command object for emitter mesh (see ParamCommand).*/
        class CmdMesh : public ParamCommand
        {
        public:
            String doGet(const void* target) const;
            void doSet(void* target, const String& val);
        };

        MeshEmitter(ParticleSystem* psys);// : AreaEmitter(psys) {}

        void genEmissionDirection(Vector3& destVector);
        unsigned short _getEmissionCount(Real timeElapsed);

        /** Overloaded to update the trans. matrix */
        void setDirection( const Vector3& direction );

        /** See ParticleEmitter. */
        void _initParticle(Particle* pParticle);

        void setRandom(bool random);
        bool getRandom(void) const;

        void setCoverage(Real coverge);
        Real getCoverage(void) const;

        void setUseVertexNormals(bool vertexNormals);
        bool getUseVertexNormals(void) const;

        /** Sets the name of mesh of the emitter. */
        void setMesh(String name);
        /** Gets the name of mesh of the emitter. */
        MeshPtr getMesh(void) const;
        String getMeshName(void) const;

    protected:
        String meshName;
        MeshPtr mesh;
    bool mRandom;
    bool mUseVertexNormals;
    Real mCoverage;
    size_t vertex_count,index_count;
    Vector3* vertices;
    Vector3* normals;
    unsigned* indices;

    int currentVertex;

    void getMeshInformation(MeshPtr mesh,size_t &vertex_count,Vector3* &vertices, Vector3* &normals, size_t &index_count, unsigned* &indices, const Vector3 &position = Vector3::ZERO,const Quaternion &orient = Quaternion::IDENTITY,const Vector3 &scale = Vector3::UNIT_SCALE);

        /// Command objects
        static CmdRandom msCmdRandom;
        static CmdCoverage msCmdCoverage;
        static CmdUseVertexNormals msCmdUseVertexNormals;
        static CmdMesh msCmdMesh;

    };

}

#endif

MeshEmitter.cpp

#include "OgreMeshEmitter.h"
#include "OgreParticle.h"
#include "OgreQuaternion.h"
#include "OgreException.h"
#include "OgreStringConverter.h"
#include "OgreMeshManager.h"
#include "Ogre.h"

namespace Ogre {

    // Instatiate statics
    MeshEmitter::CmdMesh MeshEmitter::msCmdMesh;
    MeshEmitter::CmdRandom MeshEmitter::msCmdRandom;
    MeshEmitter::CmdCoverage MeshEmitter::msCmdCoverage;
    MeshEmitter::CmdUseVertexNormals MeshEmitter::msCmdUseVertexNormals;

    //-----------------------------------------------------------------------
    MeshEmitter::MeshEmitter(ParticleSystem* psys)
        : ParticleEmitter(psys)
    {
        mType = "Mesh";

        mDirection = Vector3::UNIT_Z;
        mUp = Vector3::UNIT_Z;

    currentVertex = 0;
    mRandom = true;
    mCoverage = 0.0;
    mUseVertexNormals = true;
        if (createParamDictionary("MeshEmitter"))
        {

            addBaseParameters();
            ParamDictionary* pDict = getParamDictionary();

            pDict->addParameter(ParameterDef("mesh", 
                "Mesh for use as emitter",
                PT_REAL),&msCmdMesh);
            pDict->addParameter(ParameterDef("random", 
                "vertices emit in random order",
                PT_BOOL),&msCmdRandom);
            pDict->addParameter(ParameterDef("coverage", 
                "percentage of vertices emitting",
                PT_BOOL),&msCmdCoverage);
            pDict->addParameter(ParameterDef("use_vertex_normals", 
                "get particle direction from vertex normal",
                PT_BOOL),&msCmdUseVertexNormals);
        }
    }

    void MeshEmitter::_initParticle(Particle* pParticle)
    {
        Vector3 offset;
    Vector3 scale;

    // Call superclass
        ParticleEmitter::_initParticle(pParticle);

    if (mRandom)
        currentVertex = rand() % vertex_count;
    else
    {
        currentVertex++;
        if (currentVertex==vertex_count)
            currentVertex = 0;
    }
    offset = vertices[currentVertex];

    scale = mParent->getParentNode()->getScale();
    pParticle->position = mPosition + (offset * scale);
    

    // Generate complex data by reference
    genEmissionColour(pParticle->colour);
    genEmissionDirection(pParticle->direction);
    genEmissionVelocity(pParticle->direction);

    // Generate simpler data
    pParticle->timeToLive = pParticle->totalTimeToLive = genEmissionTTL();
    }

    //-----------------------------------------------------------------------
    void MeshEmitter::setRandom(bool random)
    {
        mRandom = random;
    }
    //-----------------------------------------------------------------------
    bool MeshEmitter::getRandom(void) const
    {
        return mRandom;
    }
    //-----------------------------------------------------------------------
    void MeshEmitter::setCoverage(Real coverage)
    {
        mCoverage = coverage;
    }
    //-----------------------------------------------------------------------
    Real MeshEmitter::getCoverage(void) const
    {
        return mCoverage;
    }
    //-----------------------------------------------------------------------
    void MeshEmitter::setUseVertexNormals(bool vertexNormals)
    {
        mUseVertexNormals = vertexNormals;
    }
    //-----------------------------------------------------------------------
    bool MeshEmitter::getUseVertexNormals(void) const
    {
        return mUseVertexNormals;
    }
    //-----------------------------------------------------------------------
    void MeshEmitter::setMesh(String name)
    {
    meshName = name;
    mesh = MeshManager::getSingleton().load(name, ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME);
    getMeshInformation(mesh,vertex_count,vertices,normals,index_count,indices);
    }
    //-----------------------------------------------------------------------
    String MeshEmitter::getMeshName(void) const
    {
        return meshName;
    }
    //-----------------------------------------------------------------------
    MeshPtr MeshEmitter::getMesh(void) const
    {
        return mesh;
    }
    //-----------------------------------------------------------------------
    void MeshEmitter::genEmissionDirection(Vector3& destVector)
    {
    if (mUseVertexNormals)
    {
        if (mAngle != Radian(0))
        {
        // Randomise angle
        Radian angle = Math::UnitRandom() * mAngle;
    
        // Randomise direction
        destVector = normals[currentVertex].randomDeviant(angle, mUp);
        }
        else
        {
        // Constant angle
        destVector = normals[currentVertex];
        }
    }
    else
        ParticleEmitter::genEmissionDirection(destVector);
    }
    //-----------------------------------------------------------------------
    unsigned short MeshEmitter::_getEmissionCount(Real timeElapsed)
    {
        // Use basic constant emission 
    unsigned short mod = vertex_count*mCoverage;
    if (mod==0)
        mod = 1;
        return genConstantEmissionCount(timeElapsed)*mod;
    }
    //-----------------------------------------------------------------------
    void MeshEmitter::setDirection( const Vector3& direction )
    {
        ParticleEmitter::setDirection( direction );

    }

    //-----------------------------------------------------------------------
    // Command objects
    //-----------------------------------------------------------------------
    //-----------------------------------------------------------------------
    String MeshEmitter::CmdRandom::doGet(const void* target) const
    {
        return StringConverter::toString(
            static_cast<const MeshEmitter*>(target)->getRandom() );
    }
    void MeshEmitter::CmdRandom::doSet(void* target, const String& val)
    {
        static_cast<MeshEmitter*>(target)->setRandom(StringConverter::parseBool(val));
    }
    //-----------------------------------------------------------------------
    String MeshEmitter::CmdCoverage::doGet(const void* target) const
    {
        return StringConverter::toString(
            static_cast<const MeshEmitter*>(target)->getCoverage() );
    }
    void MeshEmitter::CmdCoverage::doSet(void* target, const String& val)
    {
        static_cast<MeshEmitter*>(target)->setCoverage(StringConverter::parseReal(val));
    }
    //-----------------------------------------------------------------------
    String MeshEmitter::CmdUseVertexNormals::doGet(const void* target) const
    {
        return StringConverter::toString(
            static_cast<const MeshEmitter*>(target)->getUseVertexNormals() );
    }
    void MeshEmitter::CmdUseVertexNormals::doSet(void* target, const String& val)
    {
        static_cast<MeshEmitter*>(target)->setUseVertexNormals(StringConverter::parseBool(val));
    }
    //-----------------------------------------------------------------------
    String MeshEmitter::CmdMesh::doGet(const void* target) const
    {
        return static_cast<const MeshEmitter*>(target)->getMeshName();
    }
    void MeshEmitter::CmdMesh::doSet(void* target, const String& val)
    {
        static_cast<MeshEmitter*>(target)->setMesh(val);
    }

    void MeshEmitter::getMeshInformation(MeshPtr mesh,size_t &vertex_count,Vector3* &vertices, Vector3* &normals, size_t &index_count, unsigned* &indices, const Vector3 &position,const Quaternion &orient,const Vector3 &scale)
    {
        vertex_count = index_count = 0;
        
        bool added_shared = false;
        size_t current_offset = vertex_count;
        size_t shared_offset = vertex_count;
        size_t next_offset = vertex_count;
        size_t index_offset = index_count;
        size_t prev_vert = vertex_count;
        size_t prev_ind = index_count;
        
        // Calculate how many vertices and indices we're going to need
        for(int i = 0;i < mesh->getNumSubMeshes();i++)
        {
            SubMesh* submesh = mesh->getSubMesh(i);
        
            // We only need to add the shared vertices once
            if(submesh->useSharedVertices)
            {
            if(!added_shared)
            {
                VertexData* vertex_data = mesh->sharedVertexData;
                vertex_count += vertex_data->vertexCount;
                added_shared = true;
            }
            }
            else
            {
            VertexData* vertex_data = submesh->vertexData;
            vertex_count += vertex_data->vertexCount;
            }
        
            // Add the indices
            Ogre::IndexData* index_data = submesh->indexData;
            index_count += index_data->indexCount;
        }
        
        // Allocate space for the vertices and indices
        vertices = new Vector3[vertex_count];
        normals = new Vector3[vertex_count];
        indices = new unsigned[index_count];
        
        added_shared = false;
        
        // Run through the submeshes again, adding the data into the arrays
        for(int i = 0;i < mesh->getNumSubMeshes();i++)
        {
            SubMesh* submesh = mesh->getSubMesh(i);
        
            Ogre::VertexData* vertex_data = submesh->useSharedVertices ? mesh->sharedVertexData : submesh->vertexData;
            if((!submesh->useSharedVertices)||(submesh->useSharedVertices && !added_shared))
            {
            if(submesh->useSharedVertices)
            {
                added_shared = true;
                shared_offset = current_offset;
            }
        
            const Ogre::VertexElement* posElem = vertex_data->vertexDeclaration->findElementBySemantic(Ogre::VES_POSITION);
            const Ogre::VertexElement* normalElem = vertex_data->vertexDeclaration->findElementBySemantic(Ogre::VES_NORMAL);
            Ogre::HardwareVertexBufferSharedPtr vbuf = vertex_data->vertexBufferBinding->getBuffer(posElem->getSource());
            unsigned char* vertex = static_cast<unsigned char*>(vbuf->lock(Ogre::HardwareBuffer::HBL_READ_ONLY));
            Ogre::Real* pReal;
        
            for(size_t j = 0; j < vertex_data->vertexCount; ++j, vertex += vbuf->getVertexSize())
            {
                posElem->baseVertexPointerToElement(vertex, &pReal);
        
                Vector3 pt;
        
                pt.x = (*pReal++);
                pt.y = (*pReal++);
                pt.z = (*pReal++);
        
                pt = (orient * (pt * scale)) + position;
        
                vertices[current_offset + j].x = pt.x;
                vertices[current_offset + j].y = pt.y;
                vertices[current_offset + j].z = pt.z;

                normalElem->baseVertexPointerToElement(vertex, &pReal);
                pt.x = (*pReal++);
                pt.y = (*pReal++);
                pt.z = (*pReal++);

                normals[current_offset + j].x = pt.x;
                normals[current_offset + j].y = pt.y;
                normals[current_offset + j].z = pt.z;

            }
            vbuf->unlock();
            next_offset += vertex_data->vertexCount;
            }

            Ogre::IndexData* index_data = submesh->indexData;
        
            size_t numTris = index_data->indexCount / 3;
            unsigned short* pShort;
            unsigned int* pInt;
            Ogre::HardwareIndexBufferSharedPtr ibuf = index_data->indexBuffer;
            bool use32bitindexes = (ibuf->getType() == Ogre::HardwareIndexBuffer::IT_32BIT);
            if (use32bitindexes) pInt = static_cast<unsigned int*>(ibuf->lock(Ogre::HardwareBuffer::HBL_READ_ONLY));
            else pShort = static_cast<unsigned short*>(ibuf->lock(Ogre::HardwareBuffer::HBL_READ_ONLY));
        
            for(size_t k = 0; k < numTris; ++k)
            {
            size_t offset = (submesh->useSharedVertices)?shared_offset:current_offset;
        
            unsigned int vindex = use32bitindexes? *pInt++ : *pShort++;
            indices[index_offset + 0] = vindex + offset;
            vindex = use32bitindexes? *pInt++ : *pShort++;
            indices[index_offset + 1] = vindex + offset;
            vindex = use32bitindexes? *pInt++ : *pShort++;
            indices[index_offset + 2] = vindex + offset;
        
            index_offset += 3;
            }
            ibuf->unlock();
            current_offset = next_offset;
        }
    }

}