Starling Forum

1. 

   laurent d.
   

   Novice Bird
   Joined: Apr '12
   Posts: 11

   Hi,

   First of all, I'm kind-of new to low-level Stage3D.
   Basically in my experiment I'm drawing 1000 2D vector polygons using the custom DisplayObject "Polygon" approach referenced in Starling docs (http://wiki.starling-framework.org/manual/custom_display_objects).

   Each Polygon calls drawTriangles() and i simply have a for loop that creates 1000 new Polygon objects which means that each frame it calls 1000 times drawTriangles() which is actually slow but the thing is that it is actually really slow the first time i draw them as it take few seconds on my macbook pro.

   I read about batching and the fact that we must call drawTriangles() as little as possible.
   In my experiment I have 3 different kind of shape to draw, and i would like to be able to draw "n" times each type of shape on screen.
   Also i would like that when i roll over a shape its color changes so I can also experiment a bit with shaders and constant registers to add animations and/or interactivity.

   Anyone have some advice to optimize the performance here and how to achieve it ?

   I suppose that i can draw multiple distinct polygons with one drawTriangles() call. But i don't really get it .. I'm not sure how to achieve this?

   Thanks a lot for your help

   laurent.

   Posted 1 year ago #
2. 

   sHTiF
   

   Moderating Owl
   Joined: Oct '11
   Posts: 828

   drawTriangles is not that slow as many people think it is. In your case especially the first draw is slow because I suspect thats when the vertex buffer is being allocated. As for multiple vectors to batch them inside a single draw call you need to work on a single vertex buffer for all of them together which may introduce a way more overhead during synchronous buffer upload than the actual additional draw triangle calls.

   Posted 1 year ago #
3. 

   laurent d.
   

   Novice Bird
   Joined: Apr '12
   Posts: 11

   Then how can i optimize what i have so far ? Is it possible to use the same vertex buffer for multiple instances of my Polygon as they share the same shape ?

   Posted 1 year ago #
4. 

   laurent d.
   

   Novice Bird
   Joined: Apr '12
   Posts: 11

   I'm also looking for an example of a vertex buffer that contains vertices for 2 regular polygons and a vertex shader that draw them properly. I'm not sure how to do that.

   Thanks again for your help.

   Posted 1 year ago #
5. 

   sHTiF
   

   Moderating Owl
   Joined: Oct '11
   Posts: 828

   #1 yes it is possible to use same vertex buffer for clones that is what GShape does in Genome2D although what you want is to have clones inside the buffer multiple times so you can draw them in single draw call which may not always end up in better performance as you need to invalidate transformations inside the buffer as well.

   #2 what example? vertex buffer can contain any vertices you want it doesn't even know if it is one or multiple polygons nor does it care so just put them there.

   Posted 1 year ago #
6. 

   laurent d.
   

   Novice Bird
   Joined: Apr '12
   Posts: 11

   which is what i tried lets say 2 triangles at different positions but then the result on screen was not 2 triangles but one polygon. I believe there is something to do in the vertex shader right ?

   Posted 1 year ago #
7. 

   sHTiF
   

   Moderating Owl
   Joined: Oct '11
   Posts: 828

   Nope you probably had it wrong inside the vertex buffer, vertex shader goes one vertex at a time it doesn't matter what the whole picture is.

   Posted 1 year ago #
8. 

   laurent d.
   

   Novice Bird
   Joined: Apr '12
   Posts: 11

   There is something that I don't really get yet .. When I create 1000 polygons with the Polygon custom display object class in a for loop i end up at 20FPS on my macbook pro, probably because there are 1000 render() function called on each frame.
   What is the best practice here ? how would you architect the code if you had to create 1000 display objects ?

   Posted 1 year ago #

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