////  ParticleSystem.cpp//  hifi////  Created by Jeffrey on July 10, 2013// #include <glm/glm.hpp>#include "InterfaceConfig.h"#include <SharedUtil.h>#include "ParticleSystem.h"#include "Application.h" ParticleSystem::ParticleSystem() {     _gravity                = 0.005;    _numEmitters            = 1;    _bounce                 = 0.9f;    _timer                  = 0.0f;    _airFriction            = 6.0f;    _jitter                 = 0.1f;    _homeAttraction         = 0.0f;    _tornadoForce           = 0.0f;    _neighborAttraction     = 0.02f;    _neighborRepulsion      = 0.9f;    _TEST_bigSphereRadius   = 0.5f;    _TEST_bigSpherePosition = glm::vec3( 5.0f, _TEST_bigSphereRadius, 5.0f);    _numParticles           = 1500;        for (unsigned int e = 0; e < _numEmitters; e++) {            _emitter[e].position  = glm::vec3(0.0f, 0.0f, 0.0f);        _emitter[e].rotation  = glm::quat();        _emitter[e].right     = IDENTITY_RIGHT;        _emitter[e].up        = IDENTITY_UP;        _emitter[e].front     = IDENTITY_FRONT;    };          for (unsigned int p = 0; p < _numParticles; p++) {                float radian = ((float)p / (float)_numParticles) * PI_TIMES_TWO;        float wave = sinf(radian);                float red   = 0.5f + 0.5f * wave;        float green = 0.3f + 0.3f * wave;        float blue  = 0.2f - 0.2f * wave;                _particle[p].color        = glm::vec3(red, green, blue);        _particle[p].age          = 0.0f;        _particle[p].radius       = 0.01f;        _particle[p].emitterIndex = 0;        _particle[p].position     = glm::vec3(0.0f, 0.0f, 0.0f);        _particle[p].velocity     = glm::vec3(0.0f, 0.0f, 0.0f);    }        assert(_numParticles <= MAX_PARTICLES);    assert(_numEmitters  <= MAX_EMITTERS );}  void ParticleSystem::simulate(float deltaTime) {        // update emitters    for (unsigned int e = 0; e < _numEmitters; e++) {        updateEmitter(e, deltaTime);    }        // update particles    for (unsigned int p = 0; p < _numParticles; p++) {        updateParticle(p, deltaTime);    }     // apply special effects    runSpecialEffectsTest(deltaTime);} void ParticleSystem::updateEmitter(int e, float deltaTime) {     _emitter[e].front = _emitter[e].rotation * IDENTITY_FRONT;    _emitter[e].right = _emitter[e].rotation * IDENTITY_RIGHT;    _emitter[e].up    = _emitter[e].rotation * IDENTITY_UP;    } void ParticleSystem::runSpecialEffectsTest(float deltaTime) {     _timer += deltaTime;      glm::vec3 tilt = glm::vec3    (        30.0f * sinf( _timer * 0.55f ),        0.0f,        30.0f * cosf( _timer * 0.75f )    );       _emitter[0].rotation = glm::quat(glm::radians(tilt));     _gravity            = 0.01f  + 0.01f  * sinf( _timer * 0.52f );    _airFriction        = 3.0f   + 2.0f   * sinf( _timer * 0.32f );    _jitter             = 0.05f  + 0.05f  * sinf( _timer * 0.42f );    _homeAttraction     = 0.01f  + 0.01f  * cosf( _timer * 0.6f  );    _tornadoForce       = 0.0f   + 0.03f  * sinf( _timer * 0.7f  );    _neighborAttraction = 0.1f   + 0.1f   * cosf( _timer * 0.8f  );    _neighborRepulsion  = 0.4f   + 0.3f   * sinf( _timer * 0.4f  );}   void ParticleSystem::updateParticle(int p, float deltaTime) {     _particle[p].age += deltaTime;     // apply random jitter    _particle[p].velocity +=     glm::vec3    (        -_jitter * ONE_HALF + _jitter * randFloat(),         -_jitter * ONE_HALF + _jitter * randFloat(),         -_jitter * ONE_HALF + _jitter * randFloat()    ) * deltaTime;            // apply attraction to home position    glm::vec3 vectorToHome = _emitter[_particle[p].emitterIndex].position - _particle[p].position;    _particle[p].velocity += vectorToHome * _homeAttraction * deltaTime;        // apply neighbor attraction    int neighbor = p + 1;    if (neighbor == _numParticles ) {        neighbor = 0;    }    glm::vec3 vectorToNeighbor = _particle[p].position - _particle[neighbor].position;        _particle[p].velocity -= vectorToNeighbor * _neighborAttraction * deltaTime;     float distanceToNeighbor = glm::length(vectorToNeighbor);    if (distanceToNeighbor > 0.0f) {        _particle[neighbor].velocity += (vectorToNeighbor / ( 1.0f + distanceToNeighbor * distanceToNeighbor)) * _neighborRepulsion * deltaTime;    }        // apply tornado force    //glm::vec3 tornadoDirection = glm::cross(vectorToHome, _emitter[_particle[p].emitterIndex].up);    //_particle[p].velocity += tornadoDirection * _tornadoForce * deltaTime;    //_particle[p].velocity += _emitter[_particle[p].emitterIndex].up * _tornadoForce * deltaTime;     // apply air friction    float drag = 1.0 - _airFriction * deltaTime;    if (drag < 0.0f) {        _particle[p].velocity = glm::vec3(0.0f, 0.0f, 0.0f);    } else {        _particle[p].velocity *= drag;    }        // apply gravity    _particle[p].velocity.y -= _gravity * deltaTime;            // update position by velocity    _particle[p].position += _particle[p].velocity;        // collision with ground    if (_particle[p].position.y < _particle[p].radius) {        _particle[p].position.y = _particle[p].radius;                if (_particle[p].velocity.y < 0.0f) {            _particle[p].velocity.y *= -_bounce;        }    }        // collision with sphere    glm::vec3 vectorToSphereCenter = _TEST_bigSpherePosition - _particle[p].position;    float distanceToSphereCenter = glm::length(vectorToSphereCenter);    float combinedRadius = _TEST_bigSphereRadius + _particle[p].radius;    if (distanceToSphereCenter < combinedRadius) {            if (distanceToSphereCenter > 0.0f){            glm::vec3 directionToSphereCenter = vectorToSphereCenter / distanceToSphereCenter;            _particle[p].position = _TEST_bigSpherePosition - directionToSphereCenter * combinedRadius;                    }    }}  void ParticleSystem::render() {     // render the emitters    for (unsigned int e = 0; e < _numEmitters; e++) {        renderEmitter(e, 0.2f);    };       // render the particles    for (unsigned int p = 0; p < _numParticles; p++) {        renderParticle(p);    }}   void ParticleSystem::renderParticle(int p) {     glColor3f(_particle[p].color.x, _particle[p].color.y, _particle[p].color.z);    glPushMatrix();    glTranslatef(_particle[p].position.x, _particle[p].position.y, _particle[p].position.z);    glutSolidSphere(_particle[p].radius, 6, 6);    glPopMatrix();     // render velocity lines    glColor4f( _particle[p].color.x, _particle[p].color.y, _particle[p].color.z, 0.5f);    glm::vec3 end = _particle[p].position - _particle[p].velocity * 2.0f;    glBegin(GL_LINES);    glVertex3f(_particle[p].position.x, _particle[p].position.y, _particle[p].position.z);    glVertex3f(end.x, end.y, end.z);        glEnd();}   void ParticleSystem::renderEmitter(int e, float size) {        glm::vec3 r = _emitter[e].right * size;    glm::vec3 u = _emitter[e].up    * size;    glm::vec3 f = _emitter[e].front * size;     glLineWidth(2.0f);     glColor3f(0.8f, 0.4, 0.4);    glBegin(GL_LINES);    glVertex3f(_emitter[e].position.x, _emitter[e].position.y, _emitter[e].position.z);    glVertex3f(_emitter[e].position.x + r.x, _emitter[e].position.y + r.y, _emitter[e].position.z + r.z);    glEnd();     glColor3f(0.4f, 0.8, 0.4);    glBegin(GL_LINES);    glVertex3f(_emitter[e].position.x, _emitter[e].position.y, _emitter[e].position.z);    glVertex3f(_emitter[e].position.x + u.x, _emitter[e].position.y + u.y, _emitter[e].position.z + u.z);    glEnd();     glColor3f(0.4f, 0.4, 0.8);    glBegin(GL_LINES);    glVertex3f(_emitter[e].position.x, _emitter[e].position.y, _emitter[e].position.z);    glVertex3f(_emitter[e].position.x + f.x, _emitter[e].position.y + f.y, _emitter[e].position.z + f.z);    glEnd();}