collision binning bugfix, made particles less sticky, update to water…

…fall

- updated waterfall intensity and blurring

wled00/FX.cpp

@@ -8170,8 +8170,8 @@ uint16_t mode_particlewaterfall(void) {
 
     PartSys->setGravity();  // enable with default gforce
     PartSys->setKillOutOfBounds(true); // out of bounds particles dont return (except on top, taken care of by gravity setting)
-    PartSys->setMotionBlur(170); // anable motion blur
-    PartSys->setSmearBlur(45); // enable 2D blurring (smearing)
+    PartSys->setMotionBlur(180); // anable motion blur
+    PartSys->setSmearBlur(30); // enable 2D blurring (smearing)
     for (i = 0; i < PartSys->numSources; i++) {
       PartSys->sources[i].source.hue = i*90;
       PartSys->sources[i].source.collide = true; // seeded particles will collide
@@ -8207,7 +8207,7 @@ uint16_t mode_particlewaterfall(void) {
       PartSys->sources[i].source.hue += 1 + hw_random16(SEGMENT.custom1>>1); // change hue of spray source
   }
 
-  if (SEGMENT.call % (9 - (SEGMENT.intensity >> 5)) == 0 && SEGMENT.intensity > 0) { // every nth frame, emit particles, do not emit if intensity is zero
+  if (SEGMENT.call % (12 - (SEGMENT.intensity >> 5)) == 0 && SEGMENT.intensity > 0) { // every nth frame, emit particles, do not emit if intensity is zero
     for (i = 0; i < numSprays; i++) {
       PartSys->sources[i].vy = -SEGMENT.speed >> 3; // emitting speed, down
       //PartSys->sources[i].source.x = map(SEGMENT.custom3, 0, 31, 0, (PartSys->maxXpixel - numSprays * 2) * PS_P_RADIUS) + i * PS_P_RADIUS * 2; // emitter position
@@ -8224,7 +8224,7 @@ uint16_t mode_particlewaterfall(void) {
   PartSys->update();   // update and render
   return FRAMETIME;
 }
-static const char _data_FX_MODE_PARTICLEWATERFALL[] PROGMEM = "PS Waterfall@Speed,Intensity,Variation,Collide,Position,Cylinder,Walls,Ground;;!;2;pal=9,sx=15,ix=200,c1=32,c2=160,c3=17,o3=1";
+static const char _data_FX_MODE_PARTICLEWATERFALL[] PROGMEM = "PS Waterfall@Speed,Intensity,Variation,Collide,Position,Cylinder,Walls,Ground;;!;2;pal=9,sx=15,ix=200,c1=32,c2=160,o3=1";
 
 /*
 Particle Box, applies gravity to particles in either a random direction or random but only downwards (sloshing)

wled00/FXparticleSystem.cpp

@@ -841,14 +841,15 @@ void ParticleSystem2D::renderParticle(const uint32_t particleindex, const uint32
 // detect collisions in an array of particles and handle them
 // uses binning by dividing the frame into slices in x direction which is efficient if using gravity in y direction (but less efficient for FX that use forces in x direction)
 // for code simplicity, no y slicing is done, making very tall matrix configurations less efficient
+// note: also tested adding y slicing, it gives diminishing returns, some FX even get slower. FX not using gravity would benefit with a 10% FPS improvement
 void ParticleSystem2D::handleCollisions() {
   int32_t collDistSq = particleHardRadius << 1;
   collDistSq = collDistSq * collDistSq; // square it for faster comparison (square is one operation)
   // note: partices are binned in x-axis, assumption is that no more than half of the particles are in the same bin
   // if they are, collisionStartIdx is increased so each particle collides at least every second frame (which still gives decent collisions)
   constexpr uint32_t BIN_WIDTH = 6 * PS_P_RADIUS; // width of a bin in sub-pixels
   uint32_t maxBinParticles = (usedParticles + 1) / 2; // assume no more than half of the particles are in the same bin
-  uint32_t numBins = (maxX + 1) / BIN_WIDTH; // number of bins in x direction
+  uint32_t numBins = (maxX + (BIN_WIDTH -1)) / BIN_WIDTH; // number of bins in x direction
   uint16_t binIndices[maxBinParticles]; // creat array on stack for indices, 2kB max for 1024 particles (ESP32_MAXPARTICLES/2)
   uint32_t binParticleCount; // number of particles in the current bin
   uint32_t nextFrameStartIdx = 0; // index of the first particle in the next frame (set if bin overflow)
@@ -937,8 +938,7 @@ void ParticleSystem2D::collideParticles(PSparticle *particle1, PSparticle *parti
     particle2->vx -= ximpulse;
     particle2->vy -= yimpulse;
 
-    // TODO: this makes them way too sticky. maybe apply friction only every x frames? could do (SEGMENT.call & 0x03) == 0 or even 0x07
-    if (collisionHardness < surfacehardness) { // if particles are soft, they become 'sticky' i.e. apply some friction (they do pile more nicely and stop sloshing around)
+    if (collisionHardness < surfacehardness && (SEGMENT.call & 0x03) == 0) { // if particles are soft, they become 'sticky' i.e. apply some friction (they do pile more nicely and stop sloshing around)
       const uint32_t coeff = collisionHardness + (255 - PS_P_MINSURFACEHARDNESS);  // Note: could call applyFriction, but this is faster and speed is key here
       particle1->vx = ((int32_t)particle1->vx * coeff) / 255;
       particle1->vy = ((int32_t)particle1->vy * coeff) / 255;