Particle.update() missing calls to pushTransform() and popTransform() ?

[GoogleCodeExporter]

Using the particle engine did not seem to work until I added calls to 
renderContext.pushTransform() and renderContext.popTransform() to the update() 
function on Particle:

   update: function(renderContext, time) {
      if (time < this.life) {
         // Draw it ( I think this is an optimization point )
         renderContext.pushTransform();
         this.draw(renderContext, time);
         renderContext.popTransform();
         return true;
      } else {
         return false;
      }
   },

Original issue reported on code.google.com by maryrose...@gmail.com on 25 Jul 2010 at 5:56

[GoogleCodeExporter]

The particle engine underwent a recent update which was an optimization of 
sorts.  For every particle, the engine was pushing the transformation onto the 
stack, drawing, and then popping the transform.  This was using all sorts of 
unnecessary stack operations to render particles in object coordinates, when 
rendering them in world coordinates would have been fine.

If you look at the file "particle.js" in the "/spaceroids" folder, you'll 
notice that the two particle types (SimpleParticle and TrailParticle) were 
updated, slightly, to account for this optimization:

~lines 108 & 171:
Used to look like:
   renderContext.drawPoint(Point2D.ZERO);

Now look like:
   renderContext.drawPoint(this.pos);

We're rendering the particles at their position in world coordinates rather 
than object coordinates.  The old way was done by pushing the transformation 
onto the stack, shifting the transformation, drawing, then popping the 
transformation.  The new way pushes the world transformation, renders all 
particles in world coordinates, the pops the transformation.  This is much more 
efficient.

I decided to make this change, now, rather than waiting until the next version 
of the engine since it would end up affecting potentially more people that way. 

Anyway, you'll just need to update your particle classes to render at their 
position, instead of "Point2D.ZERO".  That should fix your particle drawing 
issues.

Original comment by bfatt...@gmail.com on 26 Jul 2010 at 1:29

• Changed state: WontFix

[GoogleCodeExporter]

Great.  Thanks.  One more change that was required to make it work was removing 
the call to

renderContext.setPosition(this.pos);

from the draw method of Particle in particle.js

Thanks again.

Original comment by maryrose...@gmail.com on 27 Jul 2010 at 7:27