Function xGridInit

src/SB/Core/x/xGrid.cpp:28–63

FIXME: Usual floating point problems, floating point loads get pulled to the start. Also, there's something funny going on with the malloc + memset at the end, I think they may not have used the obvious pattern for it, since changing the multiplication order for the second one generates closer machine code than the same for both lines.

// the multiplication order for the second one generates closer machine code
// than the same for both lines.
void xGridInit(xGrid* grid, const xBox* bounds, U16 nx, U16 nz, U8 ingrid_id)
{
    grid->ingrid_id = ingrid_id;
    grid->nx = nx;
    grid->nz = nz;
    grid->minx = bounds->upper.x;
    grid->minz = bounds->upper.z;
    grid->maxx = bounds->lower.x;
    grid->maxz = bounds->lower.z;
    F32 gsizex = grid->maxx - grid->minx;
    F32 gsizez = grid->maxz - grid->minz;
    grid->csizex = gsizex / nx;
    grid->csizez = gsizex / nz;

    if (__fabs(gsizex) <= 0.001f)
    {
        grid->inv_csizex = 1.0f;
    }
    else
    {
        grid->inv_csizex = nx / gsizex;
    }

    if (__fabs(gsizez) <= 0.001f)
    {
        grid->inv_csizez = 1.0f;
    }
    else
    {
        grid->inv_csizez = nz / gsizez;
    }

    grid->maxr = 0.25f * MAX(grid->csizex, grid->csizez);
    grid->cells = (xGridBound**)xMemAllocSize(nx * nz * sizeof(xGridBound*));
    memset(grid->cells, 0, sizeof(xGridBound*) * (nz * nx));
}

void xGridKill(xGrid* grid)
{