Primitives

Drawing primitives render shapes directly to a BITMAP. All colors are packed integers in 0xAARRGGBB format — use makecol(r, g, b) to create them.

Clearing

function clear_bitmap(bitmap: BITMAP | undefined): void;
function clear_to_color(bitmap: BITMAP | undefined, colour: number): void;

clear_bitmap fills with transparent black (0x000000). clear_to_color fills with an arbitrary color.

Pixels

function putpixel(bmp: BITMAP | undefined, x: number, y: number, c: number): void;
function getpixel(bmp: BITMAP | undefined, x: number, y: number): number;

getpixel returns the packed color at (x, y), or -1 if out of bounds.

Performance

getpixel and putpixel are slow — they call getImageData/fillRect per pixel. Avoid them inside tight loops.

Fast variants (_putpixel, _putpixel32, _getpixel, _getpixel32, etc.) are aliases and have the same performance characteristics in the browser.

Lines

function vline(bitmap: BITMAP | undefined, x: number, y1: number, y2: number, colour: number): void;
function hline(bitmap: BITMAP | undefined, x1: number, y: number, x2: number, colour: number): void;
function line(
  bitmap: BITMAP | undefined,
  x1: number,
  y1: number,
  x2: number,
  y2: number,
  colour: number,
): void;
function fastline(
  bitmap: BITMAP | undefined,
  x1: number,
  y1: number,
  x2: number,
  y2: number,
  colour: number,
): void;

fastline is an alias for line.

do_line

function do_line(
  bitmap: BITMAP | undefined,
  x1: number,
  y1: number,
  x2: number,
  y2: number,
  d: number,
  proc: (bmp: BITMAP, x: number, y: number, d: number) => void,
): void;

Iterates over each pixel along the line, calling proc for each one. Useful with putpixel.

Rectangles

function rect(
  bitmap: BITMAP | undefined,
  x1: number,
  y1: number,
  x2: number,
  y2: number,
  colour: number,
): void;
function rectfill(
  bitmap: BITMAP | undefined,
  x1: number,
  y1: number,
  x2: number,
  y2: number,
  colour: number,
): void;

rect draws an outline; rectfill draws a filled rectangle.

Triangles & Polygons

function triangle(
  bitmap: BITMAP | undefined,
  x1: number,
  y1: number,
  x2: number,
  y2: number,
  x3: number,
  y3: number,
  colour: number,
): void;
function polygon(
  bitmap: BITMAP | undefined,
  vertices: number,
  points: number[],
  colour: number,
): void;

polygon accepts vertices points packed as [x0, y0, x1, y1, ...] in the points array. Both draw filled shapes.

Circles & Ellipses

function circle(
  bitmap: BITMAP | undefined,
  x: number,
  y: number,
  radius: number,
  colour: number,
): void;
function circlefill(
  bitmap: BITMAP | undefined,
  x: number,
  y: number,
  radius: number,
  colour: number,
): void;
function ellipse(
  bitmap: BITMAP | undefined,
  x: number,
  y: number,
  rx: number,
  ry: number,
  colour: number,
): void;
function ellipsefill(
  bitmap: BITMAP | undefined,
  x: number,
  y: number,
  rx: number,
  ry: number,
  colour: number,
): void;

do_circle / do_ellipse

function do_circle(bmp, x, y, radius, d, proc): void;
function do_ellipse(bitmap, x, y, rx, ry, d, proc): void;

Iterate over outline pixels and call proc for each.

Arcs

function arc(
  bitmap: BITMAP | undefined,
  x: number,
  y: number,
  ang1: number,
  ang2: number,
  r: number,
  colour: number,
): void;
function do_arc(bitmap, x, y, a1, a2, r, d, proc): void;

Angles are in Allegro fixed-point format: 256 = full circle.

Splines

function spline(bmp: BITMAP | undefined, points: number[], color: number): void;

Draws a smooth curve through 8 control points packed as [x0, y0, x1, y1, x2, y2, x3, y3].

Flood fill

function floodfill(bmp: BITMAP | undefined, x: number, y: number, color: number): void;

BFS flood-fill starting at (x, y). Replaces all connected pixels of the same color with color.