Blend modes
Whenever SlopMotion has to put one image on top of another, it uses a blend mode. The same six modes appear everywhere, so learning them once pays off across the whole tool.
| Mode | What it does | Reach for it when |
|---|---|---|
| Blend | Straight crossfade. Amount slides between the picture underneath and the layer on top. | You want a plain dissolve and predictable control. |
| Diff | Absolute difference. Matching areas go black; mismatched areas invert into hard, electric colour. | You want the layer to fight the video rather than sit on it. |
| Add | Additive light. Brightness accumulates and clips toward white. | The layer is light - glows, particles, line work, generative fields. |
| Mult | Multiply. Dark areas of the layer darken the picture; white leaves it alone. | The layer is a shadow, a grade, or a printed texture. |
| Layer | Alpha composite through a luma key. The layer's dark pixels drop out and its bright pixels sit on top. | You want a generator to appear as an object, with black treated as empty. |
| Overlay | Multiply in the shadows, screen in the highlights. Contrast goes up and the underlying image keeps its shape. | You want texture and punch without flattening the video. |
Amount is the control for all of them - and it is audio-aware, with the usual Base / Audio depth / Trigger model from Audio bands & triggers. Blend, Add, Mult, and Overlay treat it as a mix. Diff scales the layer before differencing, so the effect still fades in cleanly from zero.
Layer is the exception. There, Amount is the luma cut-off of the key rather than an opacity - turning it up raises the threshold, so more of the layer's darker pixels key away and only the brightest survive. If a Layer-mode generator vanishes as you push Amount, that is why.
Where the selector appears
On a layer. The generative and compositing layers that draw something new over the chain carry their own blend mode: Fill Layer, Grid Room, Shape Layer, Pattern, Plasma, Plexus, Superformula, Topo Contour, Universe Within, Electric Noise, Noise, and Layer Blend. Each ships with a sensible default - Fill Layer and Grid Room start on Blend, Shape Layer on Layer, Plexus and Superformula on Add - so the layer looks right before you touch anything.
Inside a group. A group's Mix control is the blend mode used between the layers stacked inside its buffer. It defaults to Add. In this position, Layer mode composites straight alpha instead of applying a luma key, and every layer contributes at full strength - each layer's own Amount already governs how strong it is. See FX groups.
On a group's output. How the finished group buffer meets the main chain. This is the only place with a seventh mode, Mask, which turns the buffer into a stencil instead of an image - see Masks.
Layers with their own smaller set
A few layers predate the shared selector and expose a narrower list:
- Mask offers Mask, Diff, Add, and Mult - its first mode multiplies the shape into the frame rather than crossfading.
- Video Map has no blend mode at all; its Mode switch chooses between using the second clip as a luma mask or as a UV displacement.
Order still matters
A blend mode only describes the meeting of two images - it does not change the fact that the chain runs top to bottom. Add on a layer near the top of the chain gets pulled through everything below it; the same layer at the bottom lands on the finished picture. When a blend mode is not doing what you expect, try moving the layer before you try another mode.