On Thursday, 11 February 2016 at 13:05:41 UTC, Claude wrote:
Hello,
I come from the C world and try to do some procedural terrain
generation, and I thought ndslice would help me to make things
look clean, but I'm very new to those semantics and I need help.
Here's my problem: I have a C-style rough implementation of a
function drawing a disk into a 2D buffer. Here it is:
import std.math;
import std.stdio;
void draw(ref float[16][16] buf, int x0, int y0, int x1, int y1)
{
float xc = cast(float)(x0 + x1) / 2;
float yc = cast(float)(y0 + y1) / 2;
float xr = cast(float)(x1 - x0) / 2;
float yr = cast(float)(y1 - y0) / 2;
float disk(size_t x, size_t y)
{
float xx, yy;
xx = (x - xc) / xr;
yy = (y - yc) / yr;
return 1.0 - sqrt(xx * xx + yy * yy);
}
for (int y = 0; y < 16; y++)
{
for (int x = 0; x < 16; x++)
{
buf[x][y] = disk(x, y);
writef(" % 3.1f", buf[x][y]);
}
writeln("");
}
}
void main()
{
float[16][16] buf;
draw(buf, 2, 2, 10, 10);
}
The final buffer contains values where positive floats are the
inside of the disk, negative are outside, and 0's represents
the perimeter of the disk.
I would like to simplify the code of draw() to make it look
more something like:
Slice!(stuff) draw(int x0, int y0, int x1, int y1)
{
float disk(size_t x, size_t y)
{
// ...same as above
}
return Slice!stuff.something!disk.somethingElseMaybe;
}
Is it possible?
Do I need to back-up the slice with an array, or could the
slice be used lazily and modified as I want using some other
drawing functions.
auto diskNoiseSlice = diskSlice.something!AddNoiseFunction;
... until I do a:
auto buf = mySlice.array;
... where the buffer would be allocated in memory and filled
with the values according to all the drawing primitives I used
on the slice.
I had a go at trying the sort of thing you are talking about:
http://dpaste.dzfl.pl/8f9da4f4cc34
That won't work with std.experimental.ndslice in 2.070.0, so
either use dmd git master or use the latest version of ndslice in
mir (https://github.com/DlangScience/mir).
