Re: [Vala] How to bitwise math and implement a jagged array in Vala?

[Evan Nemerson <evan coeus-group com>]

On Tue, 2013-07-02 at 06:36 -0500, Thomas F Steinhauer wrote:
> Dear members I am new here and I have a couple of questions and they are 
> are all centered around this piece of code I found online:
>
>  1. /*  Create checkerboard texture  */
>  2. #define checkImageWidth 64
>  3. #define checkImageHeight 64
>  4. static GLubyte checkImage[checkImageHeight][checkImageWidth][4];
>  5. static GLuint texName;
>  6. void makeCheckImage(void)
>  7. {
>  8.     int i, j, c;
>  9.
> 10.     for (i = 0; i < checkImageHeight; i++) {
> 11.        for (j = 0; j < checkImageWidth; j++) {
> 12.           c = ((((i&0x8)==0)^((j&0x8))==0))*255;
> 13.           checkImage[i][j][0] = (GLubyte) c;
> 14.           checkImage[i][j][1] = (GLubyte) c;
> 15.           checkImage[i][j][2] = (GLubyte) c;
> 16.           checkImage[i][j][3] = (GLubyte) 255;
> 17.        }
> 18.     }
> 19. }
>
> 1st, How can I do that same thing or equivalent from line #4 in Vala or 
> is it not possible?

GL.ubyte[] checkImage =
  new GL.ubyte[checkImageHeight,checkImageWidth,4];

See https://wiki.gnome.org/Vala/Tutorial#Arrays for more information.

> 2nd. When I try to run line #12 in Vala I get an error "Operation not 
> supported for types bool and bool. So is there a way to get Vala to 
> evaluate this expression correctly?

Simon already mentioned one possible solution.  However, if you want to
do it without branching, you can just cast to an integer type.
Something like this should do the trick:

c = (((GL.ubyte)((i&0x8)==0))^((GL.ubyte)((j&0x8)==0)))*255;


-Evan