jilonor Posted March 28, 2016 Share Posted March 28, 2016 Hi, I have been generating planet systems. All planets are set to pivot around the same point. There is no physics involved, just static display. this.planetSprite = game.add.sprite(x, y, skin); this.planetSprite.scale.setTo(size); this.planetSprite.anchor.setTo(0.5); this.planetSprite.pivot.x = orbite/size; this.planetSprite.rotation = getRandomInt(0,360); The rotation and display is working fine but the coordinates are not updated after rotation. Is there a specific property to call to get new coordinates or should I manually calculate it? thanks Link to comment Share on other sites More sharing options...
fillmoreb Posted March 28, 2016 Share Posted March 28, 2016 The sprite's position never actually changes, which is why you don't get a change in the coordinates. If you want the apparent position of the planet use something like this: apparent_x = x + Math.cos(rotation)*orbit_radius*scale; apparent_y = y + Math.sin(rotation)*orbit_radius*scale; EDIT: Needing to multiply by scale depends on whether you want scale to affect the orbit radius or not. That's probably obvious, I just wanted to clarify. drhayes, jilonor and Zeterain 3 Link to comment Share on other sites More sharing options...
jilonor Posted March 29, 2016 Author Share Posted March 29, 2016 Thanks for the answer Also, when I inspect the sprite properties, there is the previousPosition one which seems to contain the correct coordinates but appears to be updated asynchroniously or something... not sure. well to be accurate, I made this function in the end : function GetRotated(cx, cy, x, y, angle) { var radians = (Math.PI/180) * angle; var translatedX = (x - cx) * Math.cos(radians) - (y - cy) * Math.sin(radians) + cx; var translatedY = (x - cx) * Math.sin(radians) - (y - cy) * Math.cos(radians) + cy; return {x: parseInt(translatedX), y: parseInt(translatedY)}; } Link to comment Share on other sites More sharing options...
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