02Credits Blog

Day56 - Misc Combo Improvements

Refactored code to enable various improvements to combos


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Today I spent some time cleaning up and extracting code out from the garbage.js file into separate files. In particular I pulled all of the function I wrote for garbage rendering into the garbageRenderUtils.js and all of the functions I wrote for the clear animation into clearAnimation.js with it's own class. This made it easier to organize things in my head and allowed me to make a number of improvements to the match and combo system I have had on the todo list.

In the original game, garbage blocks would break each other if one was broken in a chain. Not only did this make it easier to clear a big stack of blocks, but it also gave the player more time to line up a combo with the falling match. Luckily implementing this feature was pretty easy. I just modified the garbage break logic I had already to add the garbage block slots to the triggering slots and loop until no more garbage blocks are broken.

  MatchStarted.Subscribe(matchedBlocks => {
  let triggeringSlots = [];
  for (let matchedBlock of matchedBlocks) {
  let garbageToBreak = new Set();
  let foundNewBrokenGarbage;
  do {
    foundNewBrokenGarbage = false;
    for (let garbage of garbageBlocks) {
      if (garbageToBreak.has(garbage)) continue;
      if (garbage.state == state.CLEARING) continue;
      for (let triggeringSlot of triggeringSlots) {
        if (garbage.adjacentTo(triggeringSlot)) {
          foundNewBrokenGarbage = true;
          triggeringSlots = triggeringSlots.concat(Array.from(garbage.overlappingSlots()));
  } while (foundNewBrokenGarbage)
  if (garbageToBreak.size != 0) {
    breakBlocks(garbageToBreak, matchedBlocks);

This has the added benefit of clearing all of the blocks at once instead of one by one. To enable this I also modified the clear animation code to keep track of multiple garbage blocks instead of just one.

  constructor(triggeringBlocks, garbageBlocks) {
  this.timer = 0;
  this.triggeringBlocks = triggeringBlocks;
  this.garbageBlocks = garbageBlocks;
  this.spawnedBlocks = [];
  for (let garbage of garbageBlocks) {
    for (let slot of garbage.overlappingSlots()) {
        visible: false,
        block: new Block(slot)


Extending Combos Through Garbage Breaks

When I wrote the initial version of garbage breaks I wrote a buggy attempt at extending combos through them which subscribed to the GarbageBroken event and added the new blocks to the trackedBlocks of a combo if any of the combo's tracked blocks participated in the breaking of the garbage. This didn't work for two reasons. First, it assumed that the combo already existed when the block was broken, and second, the garbage break event was raised before the combo could register to listen to it.

I fixed the first issue by adding a concept of matched blocks to combos and moving combo creation to the start of a match instead of the end.

  MatchStarted.Subscribe(matchedBlocks => {
  let foundExistingCombo = false;
  for (let combo of combos) {
    if (matchedBlocks.some(matchedBlock => combo.trackedBlocks.has(matchedBlock))) {
      foundExistingCombo = true;
      ComboExtended.Publish(matchedBlocks, combo.cascades);
  if (!foundExistingCombo) {
    combos.add(new Combo(matchedBlocks));

I also added a check that all of the matched blocks were cleared before dropping a combo.

  constructor(matchedBlocks) {
  this.cascades = 0;
  this.trackedBlocks = new Set();
  this.matchedBlocks = new Set();
  matchedBlocks.forEach(matchedBlock => this.matchedBlocks.add(matchedBlock));

The second problem was solved by adding a new event which gets raised on animation creation instead of garbage break. This allowed the clear animation to be established including the spawned blocks before the combo list is checked against the match.

  ClearAnimationStarted.Subscribe(({ triggeringBlocks, spawnedBlocks }) => {
  for (let combo of combos) {
    for (let block of triggeringBlocks) {
      if (combo.matchedBlocks.has(block)) {
        for (let spawnedBlock of spawnedBlocks) {

Unfortunately I don't have a graphical indication that a combo was achieved other than an extra stop clock delay, but I was able to verify that things were working as expected using console output.

Block Shadows

Unrelated to combo infrastructure I also added a shadow to the block's when being manipulated as a simple but effective effect. The basic idea is that any time a block is grown in size we can assume that said block is being raised above the grid. In this case I can draw a shadow below the block by rendering the block image without the scaling, offset by an amount proportional to the scaling and with a black and transparent tint.

  let heldDimensions = dimensions.multiply(this.scale);
let shadowOffset = (heldDimensions.width - dimensions.width);
if (shadowOffset >= 0.1) {
    imageUrl: texture || blockImages[this.type],
    position: center.add(new Vector(shadowOffset, -shadowOffset)).withZ(0),
    tint: new Color(0, 0, 0, tint.a * 0.4)

The resulting effect looks like this:


Its cheap but effective and adds some basic visual interest to the block manipulation.

Thats it for today. I think I made a bunch of progress toward the initial multiplayer version and really improved the code organization for one of the most complex parts of the game.

At this point I can confidently say that multiplayer is next. So next time I work on the project I will probably work out the exact tasks that need done server and animation wise to get a good experience going.

Till tomorrow!