Skill: Draw shapes

Written for blit386 1.8.0. The rest of blit386.dev documents the newest engine, so an API you find there may be missing from a game pinned to 1.8.0.

Draw rectangles, lines, and pixels, and clear the screen - all with palette slot numbers, all inside render().

When to use

Use to put boxes, outlines, lines, single pixels, or a background on screen, or when the user says "draw a ...".

How to do it

render() {
    BT.clear(2); // fill the whole screen with slot 2

    BT.drawRectFill(new Rect2i(10, 20, 32, 32), 1); // solid box: x, y, width, height
    BT.drawRect(new Rect2i(10, 20, 32, 32), 3); // outline only
    BT.drawLine(new Vector2i(0, 0), new Vector2i(100, 60), 3);
    BT.drawPixel(new Vector2i(50, 50), 4); // one pixel

    BT.clearRect(new Rect2i(0, 0, 64, 16), 2); // repaint just one area
}

Key calls (all methods)

• BT.clear(slot) - paint the whole frame. Call it first every frame, or last frame's drawing shows through.
• BT.drawRectFill(rect, slot) / BT.drawRect(rect, slot) - filled / outlined box.
• BT.drawLine(p0, p1, slot) - straight line between two points.
• BT.drawPixel(pos, slot) or BT.drawPixel(x, y, slot) - one pixel.
• BT.clearRect(rect, slot) - clear only a region.

Notes

• Positions are Vector2i(x, y); boxes are Rect2i(x, y, width, height). Top-left is (0, 0) and y grows downward. Whole numbers only.
• The slot number is a palette index; set up colors first (see the use-palette skill). A Color32 also works wherever a slot number does.
• BT.displaySize (a property, no parentheses) gives the screen size for centering and edges.

See docs/drawing.md.