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Transparency with Premultiplied Alpha



A new update is available for beta subscribers. Transparent materials are now supported. Unlike the old deferred renderer, our new clustered forward renderer supports transparency really really well! You can add these in a JSON material file with a Boolean property called "transparent" set to true:

"transparent": true

There are no separate blend modes now, since pre-multiplied alpha allows alpha and additive blending in a single pass. This is actually a really simple technique but for some reason all the information about it online are these horrible academic examples that don't show any clear benefit. It wasn't until I thought "how do I make shiny glass?" that I actually started looking for a way to do this.

The command Material::SetTransparent(true) replaces the old SetBlendMode(blendmode) function. GLTF materials with blending will be automatically loaded. Per-object Z-sorting is not yet supported, but transparent groups of objects will always be rendered on top of opaque objects automatically, so you don't actually need to enable sorting if you don't expect to have two layers of transparency visible anywhere..


We haven't seen a lot of transparency in games since the mid-2000s, because at the time deferred rendering was the best lighting technique. I think the capabilities of our new renderer will open up a lot of possibilities to create games that look different from anything in the past.

You can get access to the beta and private forum right now for just $5.

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I have a plan for refraction (with multiple layers) as well. And when they are implemented, shadows will work just fine.

In fact the voxel GI / reflections system should allow water without a second pass. And any surface basically has the reflective properties of water, if it is set to be reflective.

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