Engine performance issuesBlitzMax Forums/OpenGL Module/Engine performance issues
| Hi! I'm writing an OpenGL (1.0+) engine in Bmx, but it is about 50% slower than Blitz3D. I think that is a big difference.|
I'm testing it with the maplet 'test.b3d' model.
On Blitz3D, the same program runs at about 100 fps. In my engine, it runs at about 50 fps.
In my engine I have the following optimisations:
-VBO's (has no huge advantage on my system +/- 1 frame difference)
-Matrices are only updated if needed (saved about 5 frames)
-As much inline code as possible (no Matrix/Quaternion/Vertex types, just float arrays and regular functions) (saved about 10 frames)
-Floats instead of Doubles (saved about 5 frames)
I also have frustum culling, but that doesn't apply to this model, since it is a big model that is allways in view.
I can get the engine to run at 100 fps, by disabling multitexturing, and by not clearing the screen.
Could this slowness be caused by OpenGL/DirectX performance issues on my card? Is there any way to find that out? I have a very bad intergrated videocard. (SiS)
Are there any more optimisations that I could think off?
Any advice appreciated.
Last edited 2011
| On older hardware (or cheaper, like SiS or Intel), DX7 (Direct-X in general) is much better supported than OpenGL.|
I have the same problem with miniB3D - specially regarding animations: it is much slower than Blitz3D is. On good hardware you won't notice the difference, but on the lower end, Blitz3D can get much better results - probably - because of DX7.
This is one of the problems of OpenGL in general - video drivers (on Windows) are heavily optimized for DX, and just implemented (sometimes very poorly) for OGL.
I don't think there's nothing to be done - but if there is, I would very much like to hear it too... optimizing miniB3D performance even more would be awesome!
| Ah, that makes sense. However, I find a 50% difference quite a lot. |
Maybe my hardware somehow emulates some of the openGL functions. Say, multitexturing and vertex buffers?
Hopefully I'll find some ways to optimize it more. I would like to get to 75 fps. Maybe I have to think about creating some sort of quadtree system? if that is the right term.. I mean a system that culls parts of the mesh.
Last edited 2011
| I can say that OpenGL on Intel's chipsets for Windows are not as well made as compared to ATI or Nvidias, so I suspect performance with OpenGL will always be behind. There just no one to enforce compliance, as I'm sure Microsoft does for DirectX.|
But there are ways to find small performance increases, have you tried this idea?
Also remember that in Blitzmax, using Globals is slow. If you find a Global in a loop, try breaking it out as a Local variable.
And I'm sure you've already reviewed all this (part 3):
| Just a small hint: In BlitzMax Arrays are Types, too.|
So if you are really considering to increase the performance maybe you should do that stuff in plain old C instead..
Keep going, I'm looking forward to see your engine in action : )
| Thanks Adam, DTC, SLotman, I'll release the engine as opensource when (or if offcourse..) it gets more complete. |
| Or instead of arrays use pointers and memory access, but really it's about the same speed. |