Merge pull request #4820 from hyperlogic/ajt/particle-system-improvements

Improvements to particle entity.

examples/ajt-test.js

@@ -0,0 +1,93 @@
+
+(function () {
+    var spawnPoint = Vec3.sum(MyAvatar.position, Vec3.multiply(3, Quat.getFront(Camera.getOrientation())));
+
+    // constructor
+    function TestBox() {
+        this.entity = Entities.addEntity({ type: "Box",
+                                           position: spawnPoint,
+                                           dimentions: { x: 1, y: 1, z: 1 },
+                                           color: { red: 100, green: 100, blue: 255 },
+                                           gravity: { x: 0, y: 0, z: 0 },
+                                           visible: true,
+                                           locked: false,
+                                           lifetime: 6000 });
+        var self = this;
+        this.timer = Script.setInterval(function () {
+            var colorProp = { color: { red: Math.random() * 255,
+                                       green: Math.random() * 255,
+                                       blue: Math.random() * 255 } };
+            Entities.editEntity(self.entity, colorProp);
+        }, 1000);
+    }
+
+    TestBox.prototype.Destroy = function () {
+        Script.clearInterval(this.timer);
+        Entities.editEntity(this.entity, { locked: false });
+        Entities.deleteEntity(this.entity);
+    }
+
+    // constructor
+    function TestFx(color, emitDirection, emitRate, emitStrength, blinkRate) {
+        var animationSettings = JSON.stringify({ fps: 30,
+                                                 frameIndex: 0,
+                                                 running: true,
+                                                 firstFrame: 0,
+                                                 lastFrame: 30,
+                                                 loop: true });
+
+        this.entity = Entities.addEntity({ type: "ParticleEffect",
+                                           animationSettings: animationSettings,
+                                           position: spawnPoint,
+                                           textures: "http://www.hyperlogic.org/images/particle.png",
+                                           emitRate: emitRate,
+                                           emitStrength: emitStrength,
+                                           emitDirection: emitDirection,
+                                           color: color,
+                                           visible: true,
+                                           locked: false });
+
+        this.isPlaying = true;
+
+        var self = this;
+        this.timer = Script.setInterval(function () {
+            // flip is playing state
+            self.isPlaying = !self.isPlaying;
+            var animProp = { animationIsPlaying: self.isPlaying };
+            Entities.editEntity(self.entity, animProp);
+        }, (1 / blinkRate) * 1000);
+    }
+
+    TestFx.prototype.Destroy = function () {
+        Script.clearInterval(this.timer);
+        Entities.editEntity(this.entity, { locked: false });
+        Entities.deleteEntity(this.entity);
+    }
+
+    var objs = [];
+    function Init() {
+        objs.push(new TestBox());
+        objs.push(new TestFx({ red: 255, blue: 0, green: 0 },
+                             { x: 0.5, y: 1.0, z: 0.0 },
+                             100, 3, 1));
+        objs.push(new TestFx({ red: 0, blue: 255, green: 0 },
+                             { x: 0, y: 1, z: 0 },
+                             1000, 5, 0.5));
+        objs.push(new TestFx({ red: 0, blue: 0, green: 255 },
+                             { x: -0.5, y: 1, z: 0 },
+                             100, 3, 1));
+    }
+
+    function ShutDown() {
+        var i, len = objs.length;
+        for (i = 0; i < len; i++) {
+            objs[i].Destroy();
+        }
+        objs = [];
+    }
+
+    Init();
+    Script.scriptEnding.connect(ShutDown);
+})();
+
+

libraries/entities-renderer/src/RenderableParticleEffectEntityItem.cpp

@@ -16,6 +16,7 @@
 #include <DeferredLightingEffect.h>
 #include <PerfStat.h>
 #include <GeometryCache.h>
+#include "EntitiesRendererLogging.h"
 
 #include "RenderableParticleEffectEntityItem.h"
 
@@ -29,62 +30,158 @@ RenderableParticleEffectEntityItem::RenderableParticleEffectEntityItem(const Ent
 }
 
 void RenderableParticleEffectEntityItem::render(RenderArgs* args) {
-    PerformanceTimer perfTimer("RenderableParticleEffectEntityItem::render");
+
     assert(getType() == EntityTypes::ParticleEffect);
-    float pa_rad = getParticleRadius();
+    PerformanceTimer perfTimer("RenderableParticleEffectEntityItem::render");
 
-    const float MAX_COLOR = 255.0f;
-    glm::vec4 paColor(getColor()[RED_INDEX] / MAX_COLOR, getColor()[GREEN_INDEX] / MAX_COLOR,
-                    getColor()[BLUE_INDEX] / MAX_COLOR, getLocalRenderAlpha());
-
-    // Right now we're just iterating over particles and rendering as a cross of four quads.
-    // This is pretty dumb, it was quick enough to code up.  Really, there should be many
-    // rendering modes, including the all-important textured billboards.
-
-    QVector<glm::vec3>* pointVec = new QVector<glm::vec3>(_paCount * VERTS_PER_PARTICLE);
-    quint32 paIter = _paHead;
-    while (_paLife[paIter] > 0.0f) {
-        int j = paIter * XYZ_STRIDE;
-
-        pointVec->append(glm::vec3(_paPosition[j] - pa_rad, _paPosition[j + 1] + pa_rad, _paPosition[j + 2]));
-        pointVec->append(glm::vec3(_paPosition[j] + pa_rad, _paPosition[j + 1] + pa_rad, _paPosition[j + 2]));
-        pointVec->append(glm::vec3(_paPosition[j] + pa_rad, _paPosition[j + 1] - pa_rad, _paPosition[j + 2]));
-        pointVec->append(glm::vec3(_paPosition[j] - pa_rad, _paPosition[j + 1] - pa_rad, _paPosition[j + 2]));
-
-        pointVec->append(glm::vec3(_paPosition[j] + pa_rad, _paPosition[j + 1] + pa_rad, _paPosition[j + 2]));
-        pointVec->append(glm::vec3(_paPosition[j] - pa_rad, _paPosition[j + 1] + pa_rad, _paPosition[j + 2]));
-        pointVec->append(glm::vec3(_paPosition[j] - pa_rad, _paPosition[j + 1] - pa_rad, _paPosition[j + 2]));
-        pointVec->append(glm::vec3(_paPosition[j] + pa_rad, _paPosition[j + 1] - pa_rad, _paPosition[j + 2]));
-
-        pointVec->append(glm::vec3(_paPosition[j], _paPosition[j + 1] + pa_rad, _paPosition[j + 2] - pa_rad));
-        pointVec->append(glm::vec3(_paPosition[j], _paPosition[j + 1] + pa_rad, _paPosition[j + 2] + pa_rad));
-        pointVec->append(glm::vec3(_paPosition[j], _paPosition[j + 1] - pa_rad, _paPosition[j + 2] + pa_rad));
-        pointVec->append(glm::vec3(_paPosition[j], _paPosition[j + 1] - pa_rad, _paPosition[j + 2] - pa_rad));
-
-        pointVec->append(glm::vec3(_paPosition[j], _paPosition[j + 1] + pa_rad, _paPosition[j + 2] + pa_rad));
-        pointVec->append(glm::vec3(_paPosition[j], _paPosition[j + 1] + pa_rad, _paPosition[j + 2] - pa_rad));
-        pointVec->append(glm::vec3(_paPosition[j], _paPosition[j + 1] - pa_rad, _paPosition[j + 2] - pa_rad));
-        pointVec->append(glm::vec3(_paPosition[j], _paPosition[j + 1] - pa_rad, _paPosition[j + 2] + pa_rad));
-
-        paIter = (paIter + 1) % _maxParticles;
+    if (_texturesChangedFlag) {
+        if (_textures.isEmpty()) {
+            _texture.clear();
+        } else {
+            // for now use the textures string directly.
+            // Eventually we'll want multiple textures in a map or array.
+            _texture = DependencyManager::get<TextureCache>()->getTexture(_textures);
+        }
+        _texturesChangedFlag = false;
     }
 
-    DependencyManager::get<GeometryCache>()->updateVertices(_cacheID, *pointVec, paColor);
-                    
+    if (!_texture) {
+        renderUntexturedQuads(args);
+    } else if (_texture && !_texture->isLoaded()) {
+        renderUntexturedQuads(args);
+    } else {
+        renderTexturedQuads(args);
+    }
+};
+
+void RenderableParticleEffectEntityItem::renderUntexturedQuads(RenderArgs* args) {
+
+    float particleRadius = getParticleRadius();
+
+    const float MAX_COLOR = 255.0f;
+    glm::vec4 particleColor(getColor()[RED_INDEX] / MAX_COLOR,
+                            getColor()[GREEN_INDEX] / MAX_COLOR,
+                            getColor()[BLUE_INDEX] / MAX_COLOR,
+                            getLocalRenderAlpha());
+
+    glm::vec3 upOffset = args->_viewFrustum->getUp() * particleRadius;
+    glm::vec3 rightOffset = args->_viewFrustum->getRight() * particleRadius;
+
+    QVector<glm::vec3> vertices(getLivingParticleCount() * VERTS_PER_PARTICLE);
+    quint32 count = 0;
+    for (quint32 i = _particleHeadIndex; i != _particleTailIndex; i = (i + 1) % _maxParticles) {
+        glm::vec3 pos = _particlePositions[i];
+
+        // generate corners of quad, aligned to face the camera
+        vertices.append(pos - rightOffset + upOffset);
+        vertices.append(pos + rightOffset + upOffset);
+        vertices.append(pos + rightOffset - upOffset);
+        vertices.append(pos - rightOffset - upOffset);
+        count++;
+    }
+
+    // just double checking, cause if this invarient is false, we might have memory corruption bugs.
+    assert(count == getLivingParticleCount());
+
+    // update geometry cache with all the verts in model coordinates.
+    DependencyManager::get<GeometryCache>()->updateVertices(_cacheID, vertices, particleColor);
+
     glPushMatrix();
+
         glm::vec3 position = getPosition();
         glTranslatef(position.x, position.y, position.z);
         glm::quat rotation = getRotation();
         glm::vec3 axis = glm::axis(rotation);
         glRotatef(glm::degrees(glm::angle(rotation)), axis.x, axis.y, axis.z);
-        
+
         glPushMatrix();
+
             glm::vec3 positionToCenter = getCenter() - position;
             glTranslatef(positionToCenter.x, positionToCenter.y, positionToCenter.z);
-            
+
             DependencyManager::get<GeometryCache>()->renderVertices(gpu::QUADS, _cacheID);
+
         glPopMatrix();
+
+    glPopMatrix();
+}
+
+static glm::vec3 zSortAxis;
+static bool zSort(const glm::vec3& rhs, const glm::vec3& lhs) {
+    return glm::dot(rhs, ::zSortAxis) > glm::dot(lhs, ::zSortAxis);
+}
+
+void RenderableParticleEffectEntityItem::renderTexturedQuads(RenderArgs* args) {
+
+    float particleRadius = getParticleRadius();
+
+    const float MAX_COLOR = 255.0f;
+    glm::vec4 particleColor(getColor()[RED_INDEX] / MAX_COLOR,
+                            getColor()[GREEN_INDEX] / MAX_COLOR,
+                            getColor()[BLUE_INDEX] / MAX_COLOR,
+                            getLocalRenderAlpha());
+
+    QVector<glm::vec3> positions(getLivingParticleCount());
+    quint32 count = 0;
+    for (quint32 i = _particleHeadIndex; i != _particleTailIndex; i = (i + 1) % _maxParticles) {
+        positions.append(_particlePositions[i]);
+        count++;
+    }
+
+    // just double checking, cause if this invarient is false, we might have memory corruption bugs.
+    assert(count == getLivingParticleCount());
+
+    // sort particles back to front
+    ::zSortAxis = args->_viewFrustum->getDirection();
+    qSort(positions.begin(), positions.end(), zSort);
+
+    QVector<glm::vec3> vertices(getLivingParticleCount() * VERTS_PER_PARTICLE);
+    QVector<glm::vec2> textureCoords(getLivingParticleCount() * VERTS_PER_PARTICLE);
+
+    glm::vec3 upOffset = args->_viewFrustum->getUp() * particleRadius;
+    glm::vec3 rightOffset = args->_viewFrustum->getRight() * particleRadius;
+
+    for (int i = 0; i < positions.size(); i++) {
+        glm::vec3 pos = positions[i];
+
+        // generate corners of quad aligned to face the camera.
+        vertices.append(pos - rightOffset + upOffset);
+        vertices.append(pos + rightOffset + upOffset);
+        vertices.append(pos + rightOffset - upOffset);
+        vertices.append(pos - rightOffset - upOffset);
+
+        textureCoords.append(glm::vec2(0, 1));
+        textureCoords.append(glm::vec2(1, 1));
+        textureCoords.append(glm::vec2(1, 0));
+        textureCoords.append(glm::vec2(0, 0));
+    }
+
+    // update geometry cache with all the verts in model coordinates.
+    DependencyManager::get<GeometryCache>()->updateVertices(_cacheID, vertices, textureCoords, particleColor);
+
+    glEnable(GL_TEXTURE_2D);
+    glBindTexture(GL_TEXTURE_2D, _texture->getID());
+
+    glPushMatrix();
+
+        glm::vec3 position = getPosition();
+        glTranslatef(position.x, position.y, position.z);
+        glm::quat rotation = getRotation();
+        glm::vec3 axis = glm::axis(rotation);
+        glRotatef(glm::degrees(glm::angle(rotation)), axis.x, axis.y, axis.z);
+
+        glPushMatrix();
+
+            glm::vec3 positionToCenter = getCenter() - position;
+            glTranslatef(positionToCenter.x, positionToCenter.y, positionToCenter.z);
+
+            DependencyManager::get<GeometryCache>()->renderVertices(gpu::QUADS, _cacheID);
+
+        glPopMatrix();
+
     glPopMatrix();
 
-    delete pointVec;
-};
+    glDisable(GL_TEXTURE_2D);
+    glBindTexture(GL_TEXTURE_2D, 0);
+}
+

libraries/entities-renderer/src/RenderableParticleEffectEntityItem.h

@@ -12,6 +12,7 @@
 #define hifi_RenderableParticleEffectEntityItem_h
 
 #include <ParticleEffectEntityItem.h>
+#include <TextureCache.h>
 
 class RenderableParticleEffectEntityItem : public ParticleEffectEntityItem  {
 public:
@@ -19,9 +20,15 @@ public:
     RenderableParticleEffectEntityItem(const EntityItemID& entityItemID, const EntityItemProperties& properties);
     virtual void render(RenderArgs* args);
 
+    void renderUntexturedQuads(RenderArgs* args);
+    void renderTexturedQuads(RenderArgs* args);
+
 protected:
+
     int _cacheID;
-    const int VERTS_PER_PARTICLE = 16;
+    const int VERTS_PER_PARTICLE = 4;
+
+    NetworkTexturePointer _texture;
 };
 
 

libraries/entities/src/ParticleEffectEntityItem.cpp

@@ -18,12 +18,8 @@
 //  - Add controls for spread (which is currently hard-coded) and varying emission strength (not currently implemented).
 //  - Add drag.
 //  - Add some kind of support for collisions.
-//  - For simplicity, I'm currently just rendering each particle as a cross of four axis-aligned quads.  Really, we'd
-//    want multiple render modes, including (the most important) textured billboards (always facing camera).  Also, these
-//    should support animated textures.
 //  - There's no synchronization of the simulation across clients at all.  In fact, it's using rand() under the hood, so
 //    there's no gaurantee that different clients will see simulations that look anything like the other.
-//  - MORE?
 //
 //  Created by Jason Rickwald on 3/2/15.
 //
@@ -45,6 +41,7 @@
 #include "EntitiesLogging.h"
 #include "ParticleEffectEntityItem.h"
 
+const xColor ParticleEffectEntityItem::DEFAULT_COLOR = { 255, 255, 255 };
 const float ParticleEffectEntityItem::DEFAULT_ANIMATION_FRAME_INDEX = 0.0f;
 const bool ParticleEffectEntityItem::DEFAULT_ANIMATION_IS_PLAYING = false;
 const float ParticleEffectEntityItem::DEFAULT_ANIMATION_FPS = 30.0f;
@@ -55,6 +52,7 @@ const glm::vec3 ParticleEffectEntityItem::DEFAULT_EMIT_DIRECTION(0.0f, 1.0f, 0.0
 const float ParticleEffectEntityItem::DEFAULT_EMIT_STRENGTH = 25.0f;
 const float ParticleEffectEntityItem::DEFAULT_LOCAL_GRAVITY = -9.8f;
 const float ParticleEffectEntityItem::DEFAULT_PARTICLE_RADIUS = 0.025f;
+const QString ParticleEffectEntityItem::DEFAULT_TEXTURES = "";
 
 
 EntityItem* ParticleEffectEntityItem::factory(const EntityItemID& entityID, const EntityItemProperties& properties) {
@@ -63,40 +61,40 @@ EntityItem* ParticleEffectEntityItem::factory(const EntityItemID& entityID, cons
 
 // our non-pure virtual subclass for now...
 ParticleEffectEntityItem::ParticleEffectEntityItem(const EntityItemID& entityItemID, const EntityItemProperties& properties) :
-    EntityItem(entityItemID, properties) {
+    EntityItem(entityItemID, properties),
+    _maxParticles(DEFAULT_MAX_PARTICLES),
+    _lifespan(DEFAULT_LIFESPAN),
+    _emitRate(DEFAULT_EMIT_RATE),
+    _emitDirection(DEFAULT_EMIT_DIRECTION),
+    _emitStrength(DEFAULT_EMIT_STRENGTH),
+    _localGravity(DEFAULT_LOCAL_GRAVITY),
+    _particleRadius(DEFAULT_PARTICLE_RADIUS),
+    _lastAnimated(usecTimestampNow()),
+    _animationLoop(),
+    _animationSettings(),
+    _textures(DEFAULT_TEXTURES),
+    _texturesChangedFlag(false),
+    _shapeType(SHAPE_TYPE_NONE),
+    _particleLifetimes(DEFAULT_MAX_PARTICLES, 0.0f),
+    _particlePositions(DEFAULT_MAX_PARTICLES, glm::vec3(0.0f, 0.0f, 0.0f)),
+    _particleVelocities(DEFAULT_MAX_PARTICLES, glm::vec3(0.0f, 0.0f, 0.0f)),
+    _timeUntilNextEmit(0.0f),
+    _particleHeadIndex(0),
+    _particleTailIndex(0),
+    _particleMaxBound(glm::vec3(1.0f, 1.0f, 1.0f)),
+    _particleMinBound(glm::vec3(-1.0f, -1.0f, -1.0f)) {
+
     _type = EntityTypes::ParticleEffect;
-    _maxParticles = DEFAULT_MAX_PARTICLES;
-    _lifespan = DEFAULT_LIFESPAN;
-    _emitRate = DEFAULT_EMIT_RATE;
-    _emitDirection = DEFAULT_EMIT_DIRECTION;
-    _emitStrength = DEFAULT_EMIT_STRENGTH;
-    _localGravity = DEFAULT_LOCAL_GRAVITY;
-    _particleRadius = DEFAULT_PARTICLE_RADIUS;
+    setColor(DEFAULT_COLOR);
     setProperties(properties);
-    // this is a pretty dumb thing to do, and it should probably be changed to use a more dynamic
-    // data structure in the future.  I'm just trying to get some code out the door for now (and it's
-    // at least time efficient (though not space efficient).
-    // Also, this being a real-time application, it's doubtful we'll ever have millions of particles
-    // to keep track of, so this really isn't all that bad.
-    _paLife = new float[_maxParticles];
-    _paPosition = new float[_maxParticles * XYZ_STRIDE]; // x,y,z
-    _paVelocity = new float[_maxParticles * XYZ_STRIDE]; // x,y,z
-    _paXmax = _paYmax = _paZmax = 1.0f;
-    _paXmin = _paYmin = _paZmin = -1.0f;
-    _randSeed = (unsigned int) glm::abs(_lifespan + _emitRate + _localGravity + getPosition().x + getPosition().y + getPosition().z);
-    resetSimulation();
-    _lastAnimated = usecTimestampNow();
 }
 
 ParticleEffectEntityItem::~ParticleEffectEntityItem() {
-    delete [] _paLife;
-    delete [] _paPosition;
-    delete [] _paVelocity;
 }
 
 EntityItemProperties ParticleEffectEntityItem::getProperties() const {
     EntityItemProperties properties = EntityItem::getProperties(); // get the properties from our base class
-    
+
     COPY_ENTITY_PROPERTY_TO_PROPERTIES(color, getXColor);
     COPY_ENTITY_PROPERTY_TO_PROPERTIES(animationIsPlaying, getAnimationIsPlaying);
     COPY_ENTITY_PROPERTY_TO_PROPERTIES(animationFrameIndex, getAnimationFrameIndex);
@@ -111,6 +109,7 @@ EntityItemProperties ParticleEffectEntityItem::getProperties() const {
     COPY_ENTITY_PROPERTY_TO_PROPERTIES(emitStrength, getEmitStrength);
     COPY_ENTITY_PROPERTY_TO_PROPERTIES(localGravity, getLocalGravity);
     COPY_ENTITY_PROPERTY_TO_PROPERTIES(particleRadius, getParticleRadius);
+    COPY_ENTITY_PROPERTY_TO_PROPERTIES(textures, getTextures);
 
     return properties;
 }
@@ -132,6 +131,7 @@ bool ParticleEffectEntityItem::setProperties(const EntityItemProperties& propert
     SET_ENTITY_PROPERTY_FROM_PROPERTIES(emitStrength, setEmitStrength);
     SET_ENTITY_PROPERTY_FROM_PROPERTIES(localGravity, setLocalGravity);
     SET_ENTITY_PROPERTY_FROM_PROPERTIES(particleRadius, setParticleRadius);
+    SET_ENTITY_PROPERTY_FROM_PROPERTIES(textures, setTextures);
 
     if (somethingChanged) {
         bool wantDebug = false;
@@ -147,8 +147,8 @@ bool ParticleEffectEntityItem::setProperties(const EntityItemProperties& propert
 }
 
 int ParticleEffectEntityItem::readEntitySubclassDataFromBuffer(const unsigned char* data, int bytesLeftToRead,
-    ReadBitstreamToTreeParams& args,
-    EntityPropertyFlags& propertyFlags, bool overwriteLocalData) {
+                                                               ReadBitstreamToTreeParams& args,
+                                                               EntityPropertyFlags& propertyFlags, bool overwriteLocalData) {
 
     int bytesRead = 0;
     const unsigned char* dataAt = data;
@@ -186,6 +186,7 @@ int ParticleEffectEntityItem::readEntitySubclassDataFromBuffer(const unsigned ch
     READ_ENTITY_PROPERTY(PROP_EMIT_STRENGTH, float, _emitStrength);
     READ_ENTITY_PROPERTY(PROP_LOCAL_GRAVITY, float, _localGravity);
     READ_ENTITY_PROPERTY(PROP_PARTICLE_RADIUS, float, _particleRadius);
+    READ_ENTITY_PROPERTY(PROP_TEXTURES, QString, _textures);
 
     return bytesRead;
 }
@@ -194,7 +195,7 @@ int ParticleEffectEntityItem::readEntitySubclassDataFromBuffer(const unsigned ch
 // TODO: eventually only include properties changed since the params.lastViewFrustumSent time
 EntityPropertyFlags ParticleEffectEntityItem::getEntityProperties(EncodeBitstreamParams& params) const {
     EntityPropertyFlags requestedProperties = EntityItem::getEntityProperties(params);
-    
+
     requestedProperties += PROP_COLOR;
     requestedProperties += PROP_ANIMATION_FPS;
     requestedProperties += PROP_ANIMATION_FRAME_INDEX;
@@ -208,17 +209,18 @@ EntityPropertyFlags ParticleEffectEntityItem::getEntityProperties(EncodeBitstrea
     requestedProperties += PROP_EMIT_STRENGTH;
     requestedProperties += PROP_LOCAL_GRAVITY;
     requestedProperties += PROP_PARTICLE_RADIUS;
+    requestedProperties += PROP_TEXTURES;
 
     return requestedProperties;
 }
 
 void ParticleEffectEntityItem::appendSubclassData(OctreePacketData* packetData, EncodeBitstreamParams& params,
-    EntityTreeElementExtraEncodeData* modelTreeElementExtraEncodeData,
-    EntityPropertyFlags& requestedProperties,
-    EntityPropertyFlags& propertyFlags,
-    EntityPropertyFlags& propertiesDidntFit,
-    int& propertyCount,
-    OctreeElement::AppendState& appendState) const {
+                                                  EntityTreeElementExtraEncodeData* modelTreeElementExtraEncodeData,
+                                                  EntityPropertyFlags& requestedProperties,
+                                                  EntityPropertyFlags& propertyFlags,
+                                                  EntityPropertyFlags& propertiesDidntFit,
+                                                  int& propertyCount,
+                                                  OctreeElement::AppendState& appendState) const {
 
     bool successPropertyFits = true;
     APPEND_ENTITY_PROPERTY(PROP_COLOR, appendColor, getColor());
@@ -234,11 +236,12 @@ void ParticleEffectEntityItem::appendSubclassData(OctreePacketData* packetData,
     APPEND_ENTITY_PROPERTY(PROP_EMIT_STRENGTH, appendValue, getEmitStrength());
     APPEND_ENTITY_PROPERTY(PROP_LOCAL_GRAVITY, appendValue, getLocalGravity());
     APPEND_ENTITY_PROPERTY(PROP_PARTICLE_RADIUS, appendValue, getParticleRadius());
+    APPEND_ENTITY_PROPERTY(PROP_TEXTURES, appendValue, getTextures());
 }
 
 bool ParticleEffectEntityItem::isAnimatingSomething() const {
-    return getAnimationIsPlaying() &&
-        getAnimationFPS() != 0.0f;
+    // keep animating if there are particles still alive.
+    return (getAnimationIsPlaying() || getLivingParticleCount() > 0) && getAnimationFPS() != 0.0f;
 }
 
 bool ParticleEffectEntityItem::needsToCallUpdate() const {
@@ -246,33 +249,25 @@ bool ParticleEffectEntityItem::needsToCallUpdate() const {
 }
 
 void ParticleEffectEntityItem::update(const quint64& now) {
+
+    float deltaTime = (float)(now - _lastAnimated) / (float)USECS_PER_SECOND;
+     _lastAnimated = now;
+
     // only advance the frame index if we're playing
     if (getAnimationIsPlaying()) {
-        float deltaTime = (float)(now - _lastAnimated) / (float)USECS_PER_SECOND;
-        _lastAnimated = now;
-        float lastFrame = _animationLoop.getFrameIndex();
         _animationLoop.simulate(deltaTime);
-        float curFrame = _animationLoop.getFrameIndex();
-        if (curFrame > lastFrame) {
-            stepSimulation(deltaTime);
-        }
-        else if (curFrame < lastFrame) {
-            // we looped around, so restart the sim and only sim up to the point
-            // since the beginning of the frame range.
-            resetSimulation();
-            stepSimulation((curFrame - _animationLoop.getFirstFrame()) / _animationLoop.getFPS());
-        }
-    }
-    else {
-        _lastAnimated = now;
     }
 
-    // update the dimensions
-    glm::vec3 dims;
-    dims.x = glm::max(glm::abs(_paXmin), glm::abs(_paXmax)) * 2.0f;
-    dims.y = glm::max(glm::abs(_paYmin), glm::abs(_paYmax)) * 2.0f;
-    dims.z = glm::max(glm::abs(_paZmin), glm::abs(_paZmax)) * 2.0f;
-    setDimensions(dims);
+    if (isAnimatingSomething()) {
+        stepSimulation(deltaTime);
+
+        // update the dimensions
+        glm::vec3 dims;
+        dims.x = glm::max(glm::abs(_particleMinBound.x), glm::abs(_particleMaxBound.x)) * 2.0f;
+        dims.y = glm::max(glm::abs(_particleMinBound.y), glm::abs(_particleMaxBound.y)) * 2.0f;
+        dims.z = glm::max(glm::abs(_particleMinBound.z), glm::abs(_particleMaxBound.z)) * 2.0f;
+        setDimensions(dims);
+    }
 
     EntityItem::update(now); // let our base class handle it's updates...
 }
@@ -418,96 +413,103 @@ QString ParticleEffectEntityItem::getAnimationSettings() const {
     return jsonByteString;
 }
 
-void ParticleEffectEntityItem::stepSimulation(float deltaTime) {
-    _paXmin = _paYmin = _paZmin = -1.0f;
-    _paXmax = _paYmax = _paZmax = 1.0f;
+void ParticleEffectEntityItem::extendBounds(const glm::vec3& point) {
+    _particleMinBound.x = glm::min(_particleMinBound.x, point.x);
+    _particleMinBound.y = glm::min(_particleMinBound.y, point.y);
+    _particleMinBound.z = glm::min(_particleMinBound.z, point.z);
+    _particleMaxBound.x = glm::max(_particleMaxBound.x, point.x);
+    _particleMaxBound.y = glm::max(_particleMaxBound.y, point.y);
+    _particleMaxBound.z = glm::max(_particleMaxBound.z, point.z);
+}
 
-    // update particles
-    quint32 updateIter = _paHead;
-    while (_paLife[updateIter] > 0.0f) {
-        _paLife[updateIter] -= deltaTime;
-        if (_paLife[updateIter] <= 0.0f) {
-            _paLife[updateIter] = -1.0f;
-            _paHead = (_paHead + 1) % _maxParticles;
-            _paCount--;
+void ParticleEffectEntityItem::integrateParticle(quint32 index, float deltaTime) {
+    glm::vec3 atSquared(0.0f, 0.5f * _localGravity * deltaTime * deltaTime, 0.0f);
+    glm::vec3 at(0.0f, _localGravity * deltaTime, 0.0f);
+    _particlePositions[index] += _particleVelocities[index] * deltaTime + atSquared;
+    _particleVelocities[index] += at;
+}
+
+void ParticleEffectEntityItem::stepSimulation(float deltaTime) {
+
+    _particleMinBound = glm::vec3(-1.0f, -1.0f, -1.0f);
+    _particleMaxBound = glm::vec3(1.0f, 1.0f, 1.0f);
+
+    // update particles between head and tail
+    for (quint32 i = _particleHeadIndex; i != _particleTailIndex; i = (i + 1) % _maxParticles) {
+        _particleLifetimes[i] -= deltaTime;
+
+        // if particle has died.
+        if (_particleLifetimes[i] <= 0.0f) {
+            // move head forward
+            _particleHeadIndex = (_particleHeadIndex + 1) % _maxParticles;
         }
         else {
-            // DUMB FORWARD EULER just to get it done
-            int j = updateIter * XYZ_STRIDE;
-            _paPosition[j] += _paVelocity[j] * deltaTime;
-            _paPosition[j+1] += _paVelocity[j+1] * deltaTime;
-            _paPosition[j+2] += _paVelocity[j+2] * deltaTime;
-
-            _paXmin = glm::min(_paXmin, _paPosition[j]);
-            _paYmin = glm::min(_paYmin, _paPosition[j+1]);
-            _paZmin = glm::min(_paZmin, _paPosition[j+2]);
-            _paXmax = glm::max(_paXmax, _paPosition[j]);
-            _paYmax = glm::max(_paYmax, _paPosition[j + 1]);
-            _paZmax = glm::max(_paZmax, _paPosition[j + 2]);
-
-            // massless particles
-            _paVelocity[j + 1] += deltaTime * _localGravity;
+            integrateParticle(i, deltaTime);
+            extendBounds(_particlePositions[i]);
         }
-        updateIter = (updateIter + 1) % _maxParticles;
     }
 
-    // emit new particles
-    quint32 emitIdx = updateIter;
-    _partialEmit += ((float)_emitRate) * deltaTime;
-    quint32 birthed = (quint32)_partialEmit;
-    _partialEmit -= (float)birthed;
-    glm::vec3 randOffset;
+    // emit new particles, but only if animaiton is playing
+    if (getAnimationIsPlaying()) {
 
-    for (quint32 i = 0; i < birthed; i++) {
-        if (_paLife[emitIdx] < 0.0f) {
-            int j = emitIdx * XYZ_STRIDE;
-            _paLife[emitIdx] = _lifespan;
-            randOffset.x = (((double)rand() / (double)RAND_MAX) - 0.5) * 0.25 * _emitStrength;
-            randOffset.y = (((double)rand() / (double)RAND_MAX) - 0.5) * 0.25 * _emitStrength;
-            randOffset.z = (((double)rand() / (double)RAND_MAX) - 0.5) * 0.25 * _emitStrength;
-            _paVelocity[j] = (_emitDirection.x * _emitStrength) + randOffset.x;
-            _paVelocity[j + 1] = (_emitDirection.y * _emitStrength) + randOffset.y;
-            _paVelocity[j + 2] = (_emitDirection.z * _emitStrength) + randOffset.z;
+        float timeLeftInFrame = deltaTime;
+        while (_timeUntilNextEmit < timeLeftInFrame) {
 
-            // DUMB FORWARD EULER just to get it done
-            _paPosition[j] += _paVelocity[j] * deltaTime;
-            _paPosition[j + 1] += _paVelocity[j + 1] * deltaTime;
-            _paPosition[j + 2] += _paVelocity[j + 2] * deltaTime;
+            timeLeftInFrame -= _timeUntilNextEmit;
+            _timeUntilNextEmit = 1.0f / _emitRate;
 
-            _paXmin = glm::min(_paXmin, _paPosition[j]);
-            _paYmin = glm::min(_paYmin, _paPosition[j + 1]);
-            _paZmin = glm::min(_paZmin, _paPosition[j + 2]);
-            _paXmax = glm::max(_paXmax, _paPosition[j]);
-            _paYmax = glm::max(_paYmax, _paPosition[j + 1]);
-            _paZmax = glm::max(_paZmax, _paPosition[j + 2]);
+            // emit a new particle at tail index.
+            quint32 i = _particleTailIndex;
+            _particleLifetimes[i] = _lifespan;
 
-            // massless particles
-            // and simple gravity down
-            _paVelocity[j + 1] += deltaTime * _localGravity;
+            // jitter the _emitDirection by a random offset
+            glm::vec3 randOffset;
+            randOffset.x = (randFloat() - 0.5f) * 0.25f * _emitStrength;
+            randOffset.y = (randFloat() - 0.5f) * 0.25f * _emitStrength;
+            randOffset.z = (randFloat() - 0.5f) * 0.25f * _emitStrength;
 
-            emitIdx = (emitIdx + 1) % _maxParticles;
-            _paCount++;
+            // set initial conditions
+            _particlePositions[i] = glm::vec3(0.0f, 0.0f, 0.0f);
+            _particleVelocities[i] = _emitDirection * _emitStrength + randOffset;
+
+            integrateParticle(i, timeLeftInFrame);
+            extendBounds(_particlePositions[i]);
+
+            _particleTailIndex = (_particleTailIndex + 1) % _maxParticles;
+
+            // overflow! move head forward by one.
+            // because the case of head == tail indicates an empty array, not a full one.
+            // This can drop an existing older particle, but this is by design, newer particles are a higher priority.
+            if (_particleTailIndex == _particleHeadIndex) {
+                _particleHeadIndex = (_particleHeadIndex + 1) % _maxParticles;
+            }
         }
-        else
-            break;
+
+        _timeUntilNextEmit -= timeLeftInFrame;
     }
 }
 
-void ParticleEffectEntityItem::resetSimulation() {
-    for (quint32 i = 0; i < _maxParticles; i++) {
-        quint32 j = i * XYZ_STRIDE;
-        _paLife[i] = -1.0f;
-        _paPosition[j] = 0.0f;
-        _paPosition[j+1] = 0.0f;
-        _paPosition[j+2] = 0.0f;
-        _paVelocity[j] = 0.0f;
-        _paVelocity[j+1] = 0.0f;
-        _paVelocity[j+2] = 0.0f;
-    }
-    _paCount = 0;
-    _paHead = 0;
-    _partialEmit = 0.0f;
+void ParticleEffectEntityItem::setMaxParticles(quint32 maxParticles) {
+    _maxParticles = maxParticles;
 
-    srand(_randSeed);
+    // TODO: try to do something smart here and preserve the state of existing particles.
+
+    // resize vectors
+    _particleLifetimes.resize(_maxParticles);
+    _particlePositions.resize(_maxParticles);
+    _particleVelocities.resize(_maxParticles);
+
+    // effectivly clear all particles and start emitting new ones from scratch.
+    _particleHeadIndex = 0;
+    _particleTailIndex = 0;
+    _timeUntilNextEmit = 0.0f;
 }
 
+// because particles are in a ring buffer, this isn't trivial
+quint32 ParticleEffectEntityItem::getLivingParticleCount() const {
+    if (_particleTailIndex >= _particleHeadIndex) {
+        return _particleTailIndex - _particleHeadIndex;
+    } else {
+        return (_maxParticles - _particleHeadIndex) + _particleTailIndex;
+    }
+}

libraries/entities/src/ParticleEffectEntityItem.h

@@ -2,29 +2,6 @@
 //  ParticleEffectEntityItem.h
 //  libraries/entities/src
 //
-//  Some starter code for a particle simulation entity, which could ideally be used for a variety of effects.
-//  This is some really early and rough stuff here.  It was enough for now to just get it up and running in the interface.
-//
-//  Todo's and other notes:
-//  - The simulation should restart when the AnimationLoop's max frame is reached (or passed), but there doesn't seem
-//    to be a good way to set that max frame to something reasonable right now.
-//  - There seems to be a bug whereby entities on the edge of screen will just pop off or on.  This is probably due
-//    to my lack of understanding of how entities in the octree are picked for rendering.  I am updating the entity
-//    dimensions based on the bounds of the sim, but maybe I need to update a dirty flag or something.
-//  - This should support some kind of pre-roll of the simulation.
-//  - Just to get this out the door, I just did forward Euler integration.  There are better ways.
-//  - Gravity always points along the Y axis.  Support an actual gravity vector.
-//  - Add the ability to add arbitrary forces to the simulation.
-//  - Add controls for spread (which is currently hard-coded) and varying emission strength (not currently implemented).
-//  - Add drag.
-//  - Add some kind of support for collisions.
-//  - For simplicity, I'm currently just rendering each particle as a cross of four axis-aligned quads.  Really, we'd
-//    want multiple render modes, including (the most important) textured billboards (always facing camera).  Also, these
-//    should support animated textures.
-//  - There's no synchronization of the simulation across clients at all.  In fact, it's using rand() under the hood, so
-//    there's no gaurantee that different clients will see simulations that look anything like the other.
-//  - MORE?
-//
 //  Created by Jason Rickwald on 3/2/15.
 //
 //  Distributed under the Apache License, Version 2.0.
@@ -39,14 +16,14 @@
 
 class ParticleEffectEntityItem : public EntityItem {
 public:
-    
+
     static EntityItem* factory(const EntityItemID& entityID, const EntityItemProperties& properties);
 
     ParticleEffectEntityItem(const EntityItemID& entityItemID, const EntityItemProperties& properties);
     virtual ~ParticleEffectEntityItem();
 
     ALLOW_INSTANTIATION // This class can be instantiated
-        
+
     // methods for getting/setting all properties of this entity
     virtual EntityItemProperties getProperties() const;
     virtual bool setProperties(const EntityItemProperties& properties);
@@ -54,16 +31,16 @@ public:
     virtual EntityPropertyFlags getEntityProperties(EncodeBitstreamParams& params) const;
 
     virtual void appendSubclassData(OctreePacketData* packetData, EncodeBitstreamParams& params,
-        EntityTreeElementExtraEncodeData* modelTreeElementExtraEncodeData,
-        EntityPropertyFlags& requestedProperties,
-        EntityPropertyFlags& propertyFlags,
-        EntityPropertyFlags& propertiesDidntFit,
-        int& propertyCount,
-        OctreeElement::AppendState& appendState) const;
+                                    EntityTreeElementExtraEncodeData* modelTreeElementExtraEncodeData,
+                                    EntityPropertyFlags& requestedProperties,
+                                    EntityPropertyFlags& propertyFlags,
+                                    EntityPropertyFlags& propertiesDidntFit,
+                                    int& propertyCount,
+                                    OctreeElement::AppendState& appendState) const;
 
     virtual int readEntitySubclassDataFromBuffer(const unsigned char* data, int bytesLeftToRead,
-        ReadBitstreamToTreeParams& args,
-        EntityPropertyFlags& propertyFlags, bool overwriteLocalData);
+                                                 ReadBitstreamToTreeParams& args,
+                                                 EntityPropertyFlags& propertyFlags, bool overwriteLocalData);
 
     virtual void update(const quint64& now);
     virtual bool needsToCallUpdate() const;
@@ -71,6 +48,7 @@ public:
     const rgbColor& getColor() const { return _color; }
     xColor getXColor() const { xColor color = { _color[RED_INDEX], _color[GREEN_INDEX], _color[BLUE_INDEX] }; return color; }
 
+    static const xColor DEFAULT_COLOR;
     void setColor(const rgbColor& value) { memcpy(_color, value, sizeof(_color)); }
     void setColor(const xColor& value) {
         _color[RED_INDEX] = value.red;
@@ -109,7 +87,7 @@ public:
     float getAnimationLastFrame() const { return _animationLoop.getLastFrame(); }
 
     static const quint32 DEFAULT_MAX_PARTICLES;
-    void setMaxParticles(quint32 maxParticles) { _maxParticles = maxParticles; }
+    void setMaxParticles(quint32 maxParticles);
     quint32 getMaxParticles() const { return _maxParticles; }
 
     static const float DEFAULT_LIFESPAN;
@@ -121,7 +99,7 @@ public:
     float getEmitRate() const { return _emitRate; }
 
     static const glm::vec3 DEFAULT_EMIT_DIRECTION;
-    void setEmitDirection(glm::vec3 emitDirection) { _emitDirection = emitDirection; }
+    void setEmitDirection(glm::vec3 emitDirection) { _emitDirection = glm::normalize(emitDirection); }
     const glm::vec3& getEmitDirection() const { return _emitDirection; }
 
     static const float DEFAULT_EMIT_STRENGTH;
@@ -141,11 +119,22 @@ public:
     float getAnimationFPS() const { return _animationLoop.getFPS(); }
     QString getAnimationSettings() const;
 
+    static const QString DEFAULT_TEXTURES;
+    const QString& getTextures() const { return _textures; }
+    void setTextures(const QString& textures) {
+        if (_textures != textures) {
+            _textures = textures;
+            _texturesChangedFlag = true;
+        }
+    }
+
 protected:
 
     bool isAnimatingSomething() const;
     void stepSimulation(float deltaTime);
-    void resetSimulation();
+    void extendBounds(const glm::vec3& point);
+    void integrateParticle(quint32 index, float deltaTime);
+    quint32 getLivingParticleCount() const;
 
     // the properties of this entity
     rgbColor _color;
@@ -159,25 +148,24 @@ protected:
     quint64 _lastAnimated;
     AnimationLoop _animationLoop;
     QString _animationSettings;
+    QString _textures;
+    bool _texturesChangedFlag;
     ShapeType _shapeType = SHAPE_TYPE_NONE;
 
     // all the internals of running the particle sim
-    const quint32 XYZ_STRIDE = 3;
-    float* _paLife;
-    float* _paPosition;
-    float* _paVelocity;
-    float _partialEmit;
-    quint32 _paCount;
-    quint32 _paHead;
-    float _paXmin;
-    float _paXmax;
-    float _paYmin;
-    float _paYmax;
-    float _paZmin;
-    float _paZmax;
-    unsigned int _randSeed;
+    QVector<float> _particleLifetimes;
+    QVector<glm::vec3> _particlePositions;
+    QVector<glm::vec3> _particleVelocities;
+    float _timeUntilNextEmit;
 
+    // particle arrays are a ring buffer, use these indicies
+    // to keep track of the living particles.
+    quint32 _particleHeadIndex;
+    quint32 _particleTailIndex;
+
+    // bounding volume
+    glm::vec3 _particleMaxBound;
+    glm::vec3 _particleMinBound;
 };
 
 #endif // hifi_ParticleEffectEntityItem_h
-

libraries/networking/src/PacketHeaders.cpp

@@ -72,7 +72,7 @@ PacketVersion versionForPacketType(PacketType packetType) {
             return 1;
         case PacketTypeEntityAddOrEdit:
         case PacketTypeEntityData:
-            return VERSION_ENTITIES_ZONE_ENTITIES_STAGE_HAS_AUTOMATIC_HOURDAY;
+            return VERSION_ENTITIES_PARTICLE_ENTITIES_HAVE_TEXTURES;
         case PacketTypeEntityErase:
             return 2;
         case PacketTypeAudioStreamStats:

libraries/networking/src/PacketHeaders.h

@@ -173,5 +173,6 @@ const PacketVersion VERSION_ENTITIES_HAVE_NAMES = 19;
 const PacketVersion VERSION_ENTITIES_ZONE_ENTITIES_HAVE_ATMOSPHERE = 20;
 const PacketVersion VERSION_ENTITIES_ZONE_ENTITIES_HAVE_SKYBOX = 21;
 const PacketVersion VERSION_ENTITIES_ZONE_ENTITIES_STAGE_HAS_AUTOMATIC_HOURDAY = 22;
+const PacketVersion VERSION_ENTITIES_PARTICLE_ENTITIES_HAVE_TEXTURES = 23;
 
 #endif // hifi_PacketHeaders_h

libraries/render-utils/src/GeometryCache.cpp

@@ -721,6 +721,76 @@ void GeometryCache::updateVertices(int id, const QVector<glm::vec3>& points, con
     #endif
 }
 
+void GeometryCache::updateVertices(int id, const QVector<glm::vec3>& points, const QVector<glm::vec2>& texCoords, const glm::vec4& color) {
+    BatchItemDetails& details = _registeredVertices[id];
+
+    if (details.isCreated) {
+        details.clear();
+        #ifdef WANT_DEBUG
+            qCDebug(renderutils) << "updateVertices()... RELEASING REGISTERED";
+        #endif // def WANT_DEBUG
+    }
+
+    const int FLOATS_PER_VERTEX = 5;
+    details.isCreated = true;
+    details.vertices = points.size();
+    details.vertexSize = FLOATS_PER_VERTEX;
+
+    gpu::BufferPointer verticesBuffer(new gpu::Buffer());
+    gpu::BufferPointer colorBuffer(new gpu::Buffer());
+    gpu::Stream::FormatPointer streamFormat(new gpu::Stream::Format());
+    gpu::BufferStreamPointer stream(new gpu::BufferStream());
+
+    details.verticesBuffer = verticesBuffer;
+    details.colorBuffer = colorBuffer;
+    details.streamFormat = streamFormat;
+    details.stream = stream;
+
+    details.streamFormat->setAttribute(gpu::Stream::POSITION, 0, gpu::Element(gpu::VEC3, gpu::FLOAT, gpu::XYZ), 0);
+    details.streamFormat->setAttribute(gpu::Stream::TEXCOORD, 0, gpu::Element(gpu::VEC2, gpu::FLOAT, gpu::UV), 3 * sizeof(float));
+    details.streamFormat->setAttribute(gpu::Stream::COLOR, 1, gpu::Element(gpu::VEC4, gpu::UINT8, gpu::RGBA));
+
+    details.stream->addBuffer(details.verticesBuffer, 0, details.streamFormat->getChannels().at(0)._stride);
+    details.stream->addBuffer(details.colorBuffer, 0, details.streamFormat->getChannels().at(1)._stride);
+
+    assert(points.size() == texCoords.size());
+
+    details.vertices = points.size();
+    details.vertexSize = FLOATS_PER_VERTEX;
+
+    int compactColor = ((int(color.x * 255.0f) & 0xFF)) |
+                        ((int(color.y * 255.0f) & 0xFF) << 8) |
+                        ((int(color.z * 255.0f) & 0xFF) << 16) |
+                        ((int(color.w * 255.0f) & 0xFF) << 24);
+
+    GLfloat* vertexData = new GLfloat[details.vertices * FLOATS_PER_VERTEX];
+    GLfloat* vertex = vertexData;
+
+    int* colorData = new int[details.vertices];
+    int* colorDataAt = colorData;
+
+    for (int i = 0; i < points.size(); i++) {
+        glm::vec3 point = points[i];
+        glm::vec2 texCoord = texCoords[i];
+        *(vertex++) = point.x;
+        *(vertex++) = point.y;
+        *(vertex++) = point.z;
+        *(vertex++) = texCoord.x;
+        *(vertex++) = texCoord.y;
+
+        *(colorDataAt++) = compactColor;
+    }
+
+    details.verticesBuffer->append(sizeof(GLfloat) * FLOATS_PER_VERTEX * details.vertices, (gpu::Byte*) vertexData);
+    details.colorBuffer->append(sizeof(int) * details.vertices, (gpu::Byte*) colorData);
+    delete[] vertexData;
+    delete[] colorData;
+
+    #ifdef WANT_DEBUG
+        qCDebug(renderutils) << "new registered linestrip buffer made -- _registeredVertices.size():" << _registeredVertices.size();
+    #endif
+}
+
 void GeometryCache::renderVertices(gpu::Primitive primitiveType, int id) {
     BatchItemDetails& details = _registeredVertices[id];
     if (details.isCreated) {

libraries/render-utils/src/GeometryCache.h

@@ -198,6 +198,7 @@ public:
 
     void updateVertices(int id, const QVector<glm::vec2>& points, const glm::vec4& color);
     void updateVertices(int id, const QVector<glm::vec3>& points, const glm::vec4& color);
+    void updateVertices(int id, const QVector<glm::vec3>& points, const QVector<glm::vec2>& texCoords, const glm::vec4& color);
     void renderVertices(gpu::Primitive primitiveType, int id);
 
     /// Loads geometry from the specified URL.