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Implement glide (#154)

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Tim Mickel 2016-09-12 13:26:10 -04:00 • committed by GitHub
parent bbea1af5a3
commit 91cdec1547
1 changed files with 37 additions and 0 deletions
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37
src/blocks/scratch3_motion.js
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@ -1,5 +1,6 @@
var Cast = require('../util/cast');
var MathUtil = require('../util/math-util');
var Timer = require('../util/timer');
function Scratch3MotionBlocks(runtime) {
/**
@ -20,6 +21,7 @@ Scratch3MotionBlocks.prototype.getPrimitives = function() {
'motion_turnright': this.turnRight,
'motion_turnleft': this.turnLeft,
'motion_pointindirection': this.pointInDirection,
'motion_glidesecstoxy': this.glide,
'motion_changexby': this.changeX,
'motion_setx': this.setX,
'motion_changeyby': this.changeY,
@ -59,6 +61,41 @@ Scratch3MotionBlocks.prototype.pointInDirection = function (args, util) {
util.target.setDirection(direction);
};
Scratch3MotionBlocks.prototype.glide = function (args, util) {
if (!util.stackFrame.timer) {
// First time: save data for future use.
util.stackFrame.timer = new Timer();
util.stackFrame.timer.start();
util.stackFrame.duration = Cast.toNumber(args.SECS);
util.stackFrame.startX = util.target.x;
util.stackFrame.startY = util.target.y;
util.stackFrame.endX = Cast.toNumber(args.X);
util.stackFrame.endY = Cast.toNumber(args.Y);
if (util.stackFrame.duration <= 0) {
// Duration too short to glide.
util.target.setXY(util.stackFrame.endX, util.stackFrame.endY);
return;
}
util.yieldFrame();
} else {
var timeElapsed = util.stackFrame.timer.timeElapsed();
if (timeElapsed < util.stackFrame.duration * 1000) {
// In progress: move to intermediate position.
var frac = timeElapsed / (util.stackFrame.duration * 1000);
var dx = frac * (util.stackFrame.endX - util.stackFrame.startX);
var dy = frac * (util.stackFrame.endY - util.stackFrame.startY);
util.target.setXY(
util.stackFrame.startX + dx,
util.stackFrame.startY + dy
);
util.yieldFrame();
} else {
// Finished: move to final position.
util.target.setXY(util.stackFrame.endX, util.stackFrame.endY);
}
}
};
Scratch3MotionBlocks.prototype.changeX = function (args, util) {
var dx = Cast.toNumber(args.DX);
util.target.setXY(util.target.x + dx, util.target.y);