Drawing a Spherical Mesh

[cyrille de brébisson]

Hello,

A couple of problems in your code...
First, your coordinates are in cartesian coordinates, from -1 to 1...
you should use triangle instead of triangle_p. Make sure that you set the xmin/xmax, ymin, ymax to -1, 1, -1, 1 if you want to see something...

ndiv=12 correspond to a HUGE number of triangles. put it to 6 or so to get started and debug... it does work with 12, but takes a LOT of time...

Code:


XX=.525731112119133606;
ZZ=.850650808352039932;
vdata={
    {-XX, 0.0, ZZ}, {XX, 0.0, ZZ}, {-XX, 0.0, -ZZ}, {XX, 0.0, -ZZ},
    {0.0, ZZ, XX}, {0.0, ZZ, -XX}, {0.0, -ZZ, XX}, {0.0, -ZZ, -XX},
    {ZZ, XX, 0.0}, {-ZZ, XX, 0.0}, {ZZ, -XX, 0.0}, {-ZZ, -XX, 0.0}
    };
tindices = {
    {0,4,1}, {0,9,4}, {9,5,4}, {4,5,8}, {4,8,1},
    {8,10,1}, {8,3,10}, {5,3,8}, {5,2,3}, {2,7,3},
    {7,10,3}, {7,6,10}, {7,11,6}, {11,0,6}, {0,1,6},
    {6,1,10}, {9,0,11}, {9,11,2}, {9,2,5}, {7,2,11} };

normalize(aa)
begin
    local dd;
    dd:=sqrt(aa(1)*aa(1)+aa(2)*aa(2)+aa(3)*aa(3));
    aa(1):=aa(1)/dd; aa(2):=aa(2)/dd; aa(3):=aa(3)/dd;
    return aa;
end;

drawtri(aa,bb,cc,div,r)
begin
    local ab={},ac={},bc={};
    local grey,i;
    
    grey:=rgb(25,125,25);
    if div <= 0 then

        triangle({aa(1),aa(2),grey,aa(3)},{bb(1),bb(2),grey,bb(3)},{cc(1),cc(2),gre​y,cc(3)});
//kill;
    else
        for i from 1 to 3 do
            ab(i):=(aa(i)+bb(i))/2;
            ac(i):=(aa(i)+cc(i))/2;
            bc(i):=(bb(i)+cc(i))/2;
        end;
        ab:=normalize(ab);
        ac:=normalize(ac);
        bc:=normalize(bc);
        drawtri(aa,ab,ac,div-1,r);
        drawtri(bb,bc,ab,div-1,r);
        drawtri(cc,ac,bc,div-1,r);
        drawtri(ab,bc,ac,div-1,r);
    end;
end;

export drawSphere()
begin
    local i,radius=50,ndiv=6;
    local white;
    
    white:=rgb(255,255,255);
    dimgrob_p(G1,320,240,white);
rect_p;

    for i from 1 to 20 do
        drawtri(vdata(tindices(i,1)+1),
                vdata(tindices(i,2)+1),
                vdata(tindices(i,3)+1),ndiv,radius);
    end;
//    blit_p(G0,G1);
end;

If it still does not work, it might be due to confusion on the triangle inputs with the other forms (for full 3D drawing). Since my version of the app is later than the one that you have, I do not remember exactly how it was before...
you could try a form along the lines of:
triangle(x1, y1, z2, x2, y2, z2, x3, y3, z3, c1, c2, c3);

Cyrille