Three translucent quads and one opaque box, composited by hand. Break the image with the wrong draw order or a stray depth write, then fix it.
Move the pointer over the image to probe a pixel; the readout shows that pixel's blend arithmetic, step by step.
What to notice. Alpha blending is not commutative: with reversed order the colours come out wrong, and with depth writes on as well the far quads vanish entirely — a near transparent surface wrote depth and occluded them. Additive and multiply survive any order, which is exactly why particle systems prefer them.
← all demos