On Sunday, 9 June 2013 at 12:09:03 UTC, bearophile wrote:
Time ago I tried simpledisplay (on 32 bit Windows) and I
remember I had to make the class Image final to have some
performance. I used it on Rosettacode too:
Hmm probably putPixel and impl.putPixel is too slow, it is called
a lot. I made the class final now and got a about 8% improvement,
using linux right now.
Eliminating those calls entirely, writing straight to the private
rawData pointer, gives about 12% improvement, since this would
get rid of calculating pixel offsets too (we can just do ptr++).
Maybe I'll expose that and try to make it somehow cross platform.
I got as high as 45 fps using that trick plus the dmd -inline
-release -O -noboundscheck flags. (The original code without
flags and without final gave me only 30 fps).
I compiled and ran on wine too and it seems to have worked.
Here's the nextState function using a pointer:
void nextState(ref World world, ref World nextWorld,
ref Xorshift rnd, Image img) {
auto pixelPointer = img.getDataPointer();
auto linePadding = img.bytesPerLine() - img.bytesPerPixel *
img.width;
auto pixelPadding = img.bytesPerPixel() - 3;
enum double div = cast(double)typeof(rnd.front()).max;
immutable nr = world.length;
immutable nc = world[0].length;
foreach (r, row; world) {
foreach (c, elem; row) {
final switch (elem) {
case Cell.empty:
*pixelPointer++ = 255;
*pixelPointer++ = 255;
*pixelPointer++ = 255;
//img.putPixel(c, r, white);
nextWorld[r][c] = (rnd.front()/div)<P_PROB ? Cell.tree
: Cell.empty;
rnd.popFront();
break;
case Cell.tree:
//img.putPixel(c, r, green);
*pixelPointer++ = 0;
*pixelPointer++ = 255;
*pixelPointer++ = 0;
foreach (rowShift; sp)
foreach (colShift; sp)
if ((r + rowShift) >= 0 && (r + rowShift) < nr &&
(c + colShift) >= 0 && (c + colShift) < nc &&
world[r + rowShift][c + colShift] ==
Cell.burning) {
nextWorld[r][c] = Cell.burning;
goto END;
}
nextWorld[r][c]=(rnd.front()/div)<F_PROB ? Cell.burning
: Cell.tree;
rnd.popFront();
END: break;
case Cell.burning:
//img.putPixel(c, r, red);
*pixelPointer++ = 0;
*pixelPointer++ = 0;
*pixelPointer++ = 255;
nextWorld[r][c] = Cell.empty;
break;
}
pixelPointer += pixelPadding;
}
pixelPointer += linePadding;
}
swap(world, nextWorld);
}
I have tried that Forest fire code with your new version and it
gives me a:
simpledisplay.d(676): Error: undefined identifier i, did you
mean variable s?
oops fixed. I added a new function but didn't even compile the
Windows version of this change (only tried linux) and made a typo
there.
