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24: Basic Game Board

For today’s hack we’re going to start putting the teVRis game board together. We’ve already looked at positioning objects in a circle around the camera, but that doesn’t solve the whole problem.

We need to position objects around just part of a circle so that we can see the whole game board at once. I’m using some magic numbers here, but this basically gives us the game board wrapped around the visible portion of a circle around the camera:

var positions = [];
var circle = {
  width: 10,
  depth: 10,
  radius: 50
};
var step = (Math.PI * .8) / cols;
var angle = Math.PI * 1.133;
for (var c = 0; c < cols; c++) {
  positions.push([]);
  for (var r = 0; r < rows; r++) {
    var y = (blockSize + 1) * r;
    // put the calculated cell position in our array
    var position = new T.Vector3(
      (cols / circle.width) + (circle.radius * Math.cos(angle)),
      y,
      (cols / circle.depth) + (circle.radius * Math.sin(angle))
    );
    positions[c].push(position);
  }
  angle += step;
}

I only need to calculate the positions for each block once, I can then re-use them at no extra cost:

var newPiece = function () {
  var piece = new T.Mesh(block.geometry.clone(), block.material.clone());
  var pos = positions[middleCol][0];

  piece.position.set(pos.x, pos.y, pos.z);
  piece.lookAt(new T.Vector3(camera.position.x, pos.y, camera.position.z));
  piece.material.opacity = 1;
  // eventually generate shapes here
  return piece;
};

Next we need to draw the player piece. We’ll call a function at every requestAnimationFrame that changes the Yposition of the piece at a given interval. In this case it’s every 1000ms or every 1s:

var dropInterval = 1000;
var lastTime = 0;
var dropCounter = 0;

// make the piece drop
var updatePosition = function (piece) {
  var y = blockSize + 1;
  var now = Date.now();
  var delta = now - lastTime;
  dropCounter += delta;

  if (dropCounter >= dropInterval) {
    if (piece.position.y > 0) {
      piece.position.y -= y;
    } else {
      piece.position.y = positions[middleCol][positions[middleCol].length - 1].y;
    }
    dropCounter = 0;
  }
  lastTime = now;
};

And that’s it for today, tomorrow we’ll look at creating some actual Tetrominoes.

Cardboctober

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About the author

A photo of Max Glenister

Max Glenister

Max Glenister is a Front-end Developer based in Oxfordshire. For work he spends his time designing, validating and implementing user interfaces. For fun he tinkers with Virtual Reality, 3D printing, embedded systems, game development and many other things.

You can keep up with Max on Github, Twitter and Reddit