Shapes

ShapeBatch renders untextured primitives — rectangles, circles, and lines — with the same model as sprites: NumPy state, groups, and one instanced draw call for the whole batch, mixed shapes included.

import fastobjects as fo

win = fo.Window(800, 600)
shapes = fo.ShapeBatch(capacity=1000)

bars = shapes.rects(3, x=[100.0, 200.0, 300.0], y=500.0, w=40.0, h=120.0,
                    color=(0.2, 0.8, 0.3, 1.0))
dots = shapes.circles(50, x=..., y=..., radius=6.0)
grid = shapes.lines(2, x1=[0.0, 400.0], y1=[300.0, 0.0],
                    x2=[800.0, 400.0], y2=[300.0, 600.0], width=1.0)

All three factories are vectorized like spawn (scalars or length-n arrays) and return the same SpriteGroup type — bars.rot += 0.1 and shapes.despawn(dots) work exactly as with sprites.

The three primitives

Rectangles — rects(n, x, y, w, h, rot=0.0, color=...). Position is the center; rot is in radians.

Circles — circles(n, x, y, radius, color=...). Rendered as a signed distance field in the fragment shader with ~1px anti-aliased edges — crisp at any size, no polygon segments. Internally the bounding box stores the diameter, so group.size reads/writes 2 * radius.

Lines — lines(n, x1, y1, x2, y2, width=1.0, color=...). Lines are API sugar: the endpoints are converted (vectorized) into a rotated rectangle with the given width. Moving a line afterwards means moving its center (group.pos) or recreating it.

Mixing shapes

Different primitives share the same batch and the same draw call:

shapes.rects(1, x=400.0, y=100.0, w=200.0, h=20.0, color=(0.9, 0.2, 0.2, 1.0))
shapes.circles(1, x=400.0, y=300.0, radius=50.0, color=(0.2, 0.5, 0.9, 0.8))
shapes.draw()   # one draw call for both

Alpha blending matches the sprites (straight alpha).

A complete example

import fastobjects as fo

win = fo.Window(800, 600, title="shapes guide")
shapes = fo.ShapeBatch(capacity=64)

spinner = shapes.rects(1, x=400.0, y=300.0, w=160.0, h=24.0,
                       color=(1.0, 0.6, 0.1, 1.0))
shapes.circles(1, x=400.0, y=300.0, radius=8.0, color=(1.0, 1.0, 1.0, 1.0))

@win.frame
def update(dt: float) -> None:
    spinner.rot += 1.5 * dt
    win.clear(0.08, 0.08, 0.10)
    win.draw(shapes)
    if win.keys[fo.KEY_ESCAPE]:
        win.request_close()

win.run()