Add the Pixel Demolition stress test example

[pvcraven]

Summary

A new stress-test example meant for showing off: Pixel Demolition.

Every pixel of the Arcade logo is a sprite: about 28,000 by default, or 71,000 with 2 px pixels. A turret fires up to 240 bullets a second. Each bullet explodes on impact, and every pixel in the blast flies off as debris, thousands at a time. With auto fire on (the default), the logo is rebuilt once it's gone, so it can run unattended for a video.

What it shows:

• Drawing: all the pixels are in one SpriteList, drawn with a single call. 60,000 sprites draw in about 3 ms.
• Collisions: the pixels are in a spatial hash with spatial_hash_cell_size=16, close to the sprite size, so each bullet and each blast only checks nearby pixels. The comments explain why the default of 128 would be slow here.
• Removal: hit pixels are simply removed. Many removals per frame are applied in one pass, thanks to Apply SpriteList removals in one pass when many are removed #2930.
• Debris, two ways (press G):
  • Python sprites: a SpriteList updated every frame.
  • GPU: each piece is written once to an instanced buffer (a 28-byte record in a ring buffer), and a vertex shader computes its arc and spin from its launch time. The shader uses Arcade's WindowBlock projection, so the debris lines up exactly with the sprites.

Controls: the mouse aims and fires (and turns off auto fire). A toggles auto fire, G switches debris mode, 1/2/3 set the pixel size, +/- change the fire rate, and R rebuilds the logo. The on-screen display shows FPS, update and draw times, and the sprite, debris and bullet counts.

Measured

Measured on my desktop in the real event loop, with the window hidden. Samples within 1.5 s of a logo rebuild are skipped, since building 71,000 sprites takes about a second:

Pixels, debris mode	Peak debris	Lowest FPS	10th percentile	Median
3 px, GPU	7,400	60	60	60
3 px, Python	6,800	38	49	60
2 px, GPU	15,500	60	60	60
2 px, Python	14,500	10	19	52

So pressing G mid-demolition shows the difference live.

Example checklist

• Example code in arcade/examples/sprite_pixel_demolition.py, with the python -m arcade.examples.sprite_pixel_demolition line.
• Doc page doc/example_code/sprite_pixel_demolition.rst, with the screenshot and the code.
• Gallery entry in doc/example_code/index.rst, under Stress Tests.
• Full-size screenshot committed. The thumbnail is generated by the docs build.

Checks

• The examples test runs it (in test mode, arcade.run() does one update and one draw).
• Full suite: 1645 passed.
• Docs built with sphinx-build -W: the page builds, and the gallery links to it.
• Ruff is clean.

The changelog has an entry under Unreleased → New Features.

🤖 Generated with Claude Code