[Lazarus] Fast drawing to canvas

[Reimar Grabowski]

On Thu, 23 Feb 2012 13:56:03 +0100
Marco van de Voort <marcov at stack.nl> wrote:

> The limit in OpenGL is going to be uploading speed.
True, the absolut limit is PCI-E transfer speed (for 2.0 it is 5GT/s with a data rate of 500MB/s so a x32 connector can do about 16GB/s). Looks more like HD speed is a bigger issue than PCI-E transfer speed.

> IIRC speed also depends
> on your opengl implementation match your videocard (iow, do not create
> opengl3 context on e.g. gf8x00 series, but do for new cards)
That's news to me. Do you have any links where I can look this up?
AFAIK this are the general upload bottlenecks:
- the driver (CPU overhead)
- conversion or reformatting of data
- the CPU bandwidth while copying the data from user space
- the PCI-E bus while transferring the data

For OpenGL it is hard to predict anything. Most of the time there isn't even one optimal way as much depends on hardware/driver combination.

R.