XNA and speeds...

[GaryTexmo]

I'm curious about XNA and drawing speeds... I'm finding I'm not getting what I would have expected. First, a little background on me. I started programming in QuickBasic and really liked the graphics library that came with it because it was very easy to work with. After rewriting the primitive functions in assembly, I found you could get very good speeds out of it... to the point where you could draw several 64000 pixel buffers to the screen, and all the calculations that go with it, still getting frame rates of 75 and up (on older hardware no less).

Now, I've been using XNA lately and am really liking it. It's very easy to use and reasonably straightforward, at least for the 2D stuff. Since there's no built-in 2D primitive library, I've made my own. The code for it is here:

http://members.shaw.ca/gtexmo/Code/X...D/Primative.cs
(I realize I spelled "Primitive" wrong... Oops!)

With this I can only put out about 23000 lines/points before I start to dip below my refresh rate's fps cap (75... vsync on). I figured that maybe sprite stamping wasn't the most efficient way to draw lines, so I figured I'd try using line primatives (as found at the following article). However, when I implemented this, I was finding I was getting roughly half the FPS of the sprite stamping method.

In all cases, the test I had with my draw method in my game class was:

for (int i = 0; i < 23000; i++)
{
  Primative.Line(<random vector>, <random vector>, 1, Color.White);
}

Is it just me or does this seem very strange? I would have thought XNA could push out more than 23000 lines without slowing down in the slightest.

[cloud255]

Well too be honest I'm not too surprised, from what I understand MS tends to exaggerate a bit when it comes to the power of XNA (never used it personally). Have you considered using OpenGL?

[GaryTexmo]

Yea, I've used OpenGL before but it's not nearly as nice to work with. In addition, OpenGL has given absolutely no consideration to 2D. I tried a long time ago making a 2D library that operated in a texture buffer and slapped it to a poly that took up the whole screen. It worked well enough, I suppose, but the obvious flaw is that the CPU is doing damn near everything.

I've thought about DirectX, but to be honest I just want something quick and easy, like QuickBasic used to be! :D Ahhh, I guess the times, they are a changin', so to speak.

Again though, don't get me wrong, XNA is fantastic, I just somehow thought it would be faster... I figured on my doing something wrong.

[cloud255]

Well you could always go and write your own optimized libraries in C++ and assembler :) Should be a fun experiment (time consuming) but then you will forever have libraries that you know perform well...