getParticleColor.cpp

   ColorF BillboardRenderer::getParticleColor(Particle const* part)
   {
      PROFILE_SCOPE(getParticleColor);
      AssertFatal(part->totalLifetime > 0, "Particle lifetime must be larger than 0.");
      F32 t = F32(part->currentAge) / F32(part->totalLifetime);
      AssertFatal(t <= 1.0f, "Out out bounds filter function for particle.");
      PROFILE_START(getParticleColor_OUTER);
      for (U32 i = 1; i < ParticleSystem::PDC_NUM_KEYS; i++)
      {
         PROFILE_START(getParticleColor_INNER);
         if (getDataBlock()->getTime(i) >= t)
         {
            F32 firstPart = t - getDataBlock()->getTime(i - 1);
            F32 total = getDataBlock()->getTime(i) -
               getDataBlock()->getTime(i - 1);

            firstPart /= total;
            ColorF outCol;
            PROFILE_START(getParticleColor_INTERPOLATE);
            outCol.interpolate(getDataBlock()->getColor(i - 1), getDataBlock()->getColor(i), firstPart);
            PROFILE_END();
            PROFILE_END();
            PROFILE_END();
            return outCol;
         }
         PROFILE_END();
      }
      PROFILE_END();
      return getDataBlock()->getColor(ParticleSystem::PDC_NUM_KEYS - 1);
   }

setupBillboard.cpp

   //-----------------------------------------------------------------------------
   // Set up particle for billboard style render
   //-----------------------------------------------------------------------------
   void BillboardRenderer::setupBillboard(Particle *part,
      Point3F *basePts,
      const MatrixF &camView,
      const ColorF &ambientColor,
      ParticleVertexType *lVerts)
   {
      PROFILE_SCOPE(setupBillboard);
      F32 width = getParticleSize(part) * 0.5f;
      F32 spinAngle = part->spinSpeed * part->currentAge * ParticleSystem::AgedSpinToRadians;

      F32 sy, cy;
      mSinCos(spinAngle, sy, cy);

      PROFILE_START(setupBillboardLerp);
      const F32 ambientLerp = mClampF(getDataBlock()->getAmbientFactor(), 0.0f, 1.0f);
      ColorF partCol = mLerp(getParticleColor(part), (getParticleColor(part) * ambientColor), ambientLerp);
      PROFILE_END();
      // fill four verts, use macro and unroll loop
#define fillVert(){ \
      lVerts->point.x = cy * basePts->x - sy * basePts->z;  \
      lVerts->point.y = 0.0f;                                \
      lVerts->point.z = sy * basePts->x + cy * basePts->z;  \
      camView.mulV( lVerts->point );                        \
      lVerts->point *= width;                               \
      lVerts->point += part->pos;                           \
      lVerts->color = partCol; } \

      // Here we deal with UVs for animated particle (billboard)
      if (getDataBlock()->getAnimateTexture())
      {
         S32 fm = (S32)(part->currentAge*(1.0 / 1000.0)*getDataBlock()->getFramesPerSec());
         U8 fm_tile = getDataBlock()->getAnimTexFrames()[fm % getDataBlock()->getNumFrames()];
         S32 uv[4];
         uv[0] = fm_tile + fm_tile / getDataBlock()->getAnimTexTiling().x;
         uv[1] = uv[0] + (getDataBlock()->getAnimTexTiling().x + 1);
         uv[2] = uv[1] + 1;
         uv[3] = uv[0] + 1;

         fillVert();
         // Here and below, we copy UVs from particle datablock's current frame's UVs (billboard)
         lVerts->texCoord = getDataBlock()->getAnimTexUVs()[uv[0]];
         ++lVerts;
         ++basePts;

         fillVert();
         lVerts->texCoord = getDataBlock()->getAnimTexUVs()[uv[1]];
         ++lVerts;
         ++basePts;

         fillVert();
         lVerts->texCoord = getDataBlock()->getAnimTexUVs()[uv[2]];
         ++lVerts;
         ++basePts;

         fillVert();
         lVerts->texCoord = getDataBlock()->getAnimTexUVs()[uv[3]];
         ++lVerts;
         ++basePts;

         return;
      }

      fillVert();
      // Here and below, we copy UVs from particle datablock's texCoords (billboard)
      lVerts->texCoord = getDataBlock()->getTexCoords(0);
      ++lVerts;
      ++basePts;

      fillVert();
      lVerts->texCoord = getDataBlock()->getTexCoords(1);
      ++lVerts;
      ++basePts;

      fillVert();
      lVerts->texCoord = getDataBlock()->getTexCoords(2);
      ++lVerts;
      ++basePts;

      fillVert();
      lVerts->texCoord = getDataBlock()->getTexCoords(3);
      ++lVerts;
      ++basePts;
   }