On Tue, May 24, 2011 at 4:25 PM, neuromit <[email protected]> wrote: > Thank you both for your suggestions, they are really helpful. I was > able to optimise my code quite a bit. > > My collision detection is pretty primitive, so I'll definitely try to > improve that. > > public boolean detectCollision(Point target, int dist) > { > return (Math.abs(this.x - target.x)<=dist && Math.abs(this.y - > target.y)<=dist); > } > > > > @Danie, you mentioned that I should split the drawing form the > animation code; What are the benefits of doing this? as both drawing > and moving are driven by the same loop?
Stuart, It is true that there must be a main loop for animation (or a game). However you ought to ensure that the drawing happens every X milliseconds, so that the frame-rate is as independent from your state computation as possible. Preferably it is a separate thread that sleeps X milliseconds, then wakes-up and paints the current state. State alone is updated constantly based on user input and game AI (in your case pressing of the buttons moves PacMan, while ghosts are chasing him automatically). If you do state updates and painting in one loop, then you will notice that game will feel differently, depending on how busy given level is (plus many more factors impeding the computation performance). What you will get, when you start optimising the collision detection is that you will no longer iterate through all points, and then the need to separate painting from state modification will be more obvious. I searched the nets for some tutorials, but found only this [*] which explains it to a lesser extent. I am sure you will be able to find something more comprehensive. Its for AWT, but the principles hold regardless. [*] http://journals.ecs.soton.ac.uk/java/tutorial/ui/drawing/animLoop.html Daniel > > On May 24, 8:33 am, Daniel Drozdzewski <[email protected]> > wrote: >> Stuart, >> >> There are few fixes straight away: >> >> - Have a predefined Paint object for your dots and use that instead >> of creating new Paint object each time you enter drawDots() >> - assign dots.size() to a local variable and keep testing that >> variable in the for loop, rather than calling size() method with each >> operation >> - don't detect collisions in your drawing code >> - worth testing whether Canvas.drawBitmap() (cached bitmap of a dot) >> could be quicker than Canvas.drawCircle(); first one only copies >> memory byte by byte, while second does some computation too >> - and finally as String said: profile it >> >> Then you have to think: >> - how complex is your collision detection? it has to be optimised and >> you should not be iterating through all dots testing for potential >> collision with PacMan; if you think about it, your dots don't move and >> PacMan moves incrementally; there are few clever strategies that you >> could use; in general collision detection optimisation strategies are >> not trivial, but I am sure you could find something that would work >> well for you and would not be too hard to implement; >> >> have a look here as an entry to possible >> ideas:http://en.wikipedia.org/wiki/Collision_detection >> >> >> >> >> >> >> >> >> >> On Tue, May 24, 2011 at 12:57 PM, neuromit <[email protected]> wrote: >> > I'm writing a pacman style game that has a lot of things to be drawn, >> > namely, the dots that pacman likes to eat. >> >> > I'm finding that the drawing of the dots is greatly hampering the >> > performance of the game. If I turn them off my app consumes much fewer >> > cpu cycles than if they are left on. >> >> > here is the code i'm using to draw the dots:http://paste2.org/p/1432169 >> >> > void drawDots(Canvas c) { >> > if (!this.drawDots) >> > return; >> >> > Paint p = new Paint(mPaint); >> > p.setColor(this.dotColor); >> > for (int i=0; i<dots.size(); i++) >> > { >> > Dot d = dots.get(i); >> > if (this.pacdroid.detectCollision(d)) >> > d.disableDot(); >> > if (d.enabled) >> > c.drawCircle(d.x, d.y,d.r, p); >> > //dots.get(i).draw(c, p); >> > } >> > } >> >> > -- >> > You received this message because you are subscribed to the Google >> > Groups "Android Developers" group. >> > To post to this group, send email to [email protected] >> > To unsubscribe from this group, send email to >> > [email protected] >> > For more options, visit this group at >> >http://groups.google.com/group/android-developers?hl=en >> >> -- >> Daniel Drozdzewski > > -- > You received this message because you are subscribed to the Google > Groups "Android Developers" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/android-developers?hl=en -- Daniel Drozdzewski -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
