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use sdl2;
use fmt;
// 2d position, x and y
export type pos = (i32, i32);
export type drawing_state = struct {
// is the mouse button held down?
drawing: bool,
pos: pos,
pictures: []picture,
};
export type picture = struct {
// the surface data as u32s
d: *[*]u32,
w: size,
h: size,
// backreference to the surface whose data we're using
surf: *sdl2::SDL_Surface,
pos: pos,
};
// Returns array index of the pixel at position pos.
// Bounds check happens in here instead of using a slice type, so
// that it's easier to remove later.
export fn pidx(pic: *picture, pos: pos) size = {
const (x,y) = pos;
const (xs,ys) = (x:size, y:size);
assert(0 <= x, "x position must not be less than 0");
assert(0 <= y, "y position must not be less than 0");
assert(xs < pic.w, "x position must be less than picture width");
assert(ys < pic.h, "y position must be less than picture height");
return xs + pic.w*ys;
};
export fn pic_set(pic: *picture, pos: pos, val: u32) void =
pic.d[pidx(pic,pos)] = val;
export fn picture_from_surface(surf: *sdl2::SDL_Surface, pos: pos) picture = picture {
w = surf.w: size,
h = surf.h: size,
d = (surf.pixels as *opaque: *[*]u32),
surf = surf,
pos = pos,
};
export fn clear_picture(pic: *picture, color: u32) void = {
for (let i = 0z; i < pic.w*pic.h; i+=1) pic.d[i] = color;
};
export fn outline_picture(pic: *picture) void = {
for (let x = 0; x:size < pic.w; x+=1) {
pic_set(pic, (x, 0), 0);
pic_set(pic, (x, pic.h:int-1), 0);
};
for (let y = 0; y:size < pic.h; y+=1) {
pic_set(pic, (0, y), 0);
pic_set(pic, (pic.w:int-1, y), 0);
};
};
fn min(a: i32, b: i32) i32 = if (a<b) a else b;
fn max(a: i32, b: i32) i32 = if (a<b) b else a;
// Draws a circle onto the picture, at given position radius color
// Clips at the boundaries of the picture to avoid overflow.
export fn circle(picture: *picture, c: pos, r: i32, color: u32) void = {
// fmt::printfln("C {} {} {} {:x}",c.0,c.1,r,color)!;
const (cx,cy) = c;
const ymin = max(0, cy-r);
const ymax = min(picture.h:i32-1, cy+r);
const xmin = max(0, cx-r);
const xmax = min(picture.w:i32-1, cx+r);
const r2 = r*r + r;
for (let y = ymin; y<=ymax; y+=1) {
const yd = y-cy;
for (let x = xmin; x<=xmax; x+=1) {
const xd = x-cx;
if (yd*yd + xd*xd <= r2) {
pic_set(picture, (x,y), color);
};
};
};
};
export fn do_drawing(dstate: *drawing_state) void = {
if (dstate.drawing) for (let i = 0z; i < 4; i+=1) {
const pic = &dstate.pictures[i];
const p = (dstate.pos.0 - pic.pos.0, dstate.pos.1 - pic.pos.1);
circle(pic, p, 20, 0xff0088);
};
};
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