Procedural drawing using ndslice

[John Colvin via Digitalmars-d-learn]

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).