When working with most drawing programs we will at some point want to use layers. Layers are handy for organizing and separating different elements of drawing. Blender's grease pencil tool also has layers and these can be especially handy in Blender. So how do we use grease pencil layers in Blender?
Grease pencil layers allow for the sorting of grease pencil drawings and also affect what order strokes are rendered in. Layers also have different blend modes which apply to strokes under them as well as the rest of the scene.
Now there is quite a bit more we can go over with the grease pencil layer system. In the rest of this article, we'll go over how the layer stacks work, and how to reorder and remove layers. We'll also go over layer blend modes, layer masks, layer adjustments, and a few useful options available for layers.
We can use layers to organize our strokes and separate them. Layers also dictate the order that strokes get rendered. Even when a stroke is behind another stroke if the layer that stroke is in is higher than the layer of the stroke it's behind it will render on top of that stroke.
Layers can also have different blend modes set to them which will apply to all grease pencils below them when that grease pencil stroke overlaps another.
We can also disable the layer ordering on a grease pencil object by going to object data properties > strokes and setting the stroke depth order to 3D location. Note that this isn't per layer but per grease pencil object.
For managing our layers we'll mainly be using the row of buttons on the left of the layers field. The + button will add a layer and the - button will remove the selected layer. The up button will move the selected layer up in the stack and the down button will move the selected layer down in the stack.
Note that there is a difference between the dropdown and the down button. The dropdown has a darker square around it and holds quite a few extra options. The dropdown does have a few useful options such as duplicate and a few other specific.
Grease pencil blend modes apply to everything under them including objects as well as grease pencil strokes in the scene. Let's say we make a stroke that is in front of our scene that includes a few objects and a few other grease pencil layers. We'll set that strokes blend mode to add and set our stroke to red.
With our grease pencil layer configured now everything under the stroke will have red additively blended onto it.
masks allow us to confine a layer to another layer. When we enable masks and then add a mask the current layer will only be visible when it overlaps the mask layer we selected.
We can also select invert mask on the right of the mask layer so that when the mask layer overlaps the current layer it cuts out the current layer.
Grease pencil masks are different than the masks we'd use for video editing and compositing. Instead, the masks are just other grease pencil layers. Something to keep in mind is that mask layers will not work if the layer we've selected is hidden. A mask layer will work even if its opacity is 0 though.
On top of how we've already configured the strokes in a layer, we can also add a few adjustments to all of the strokes in that layer with layer adjustments.
The first two options are the tint color and factor. With these, we can adjust the color of all the strokes in a layer. First set the color we want with the tint color and then use the factor to adjust how much of that color to adjust the strokes by.
Stroke thickness allows us to change the width of all the strokes in a layer at once. This doesn't make each stroke's width the same but acts sort of like a value that is added or subtracted from each stroke's width.
Besides the few main options, we also have a few others available for layers. The first of these is use lights. While not noticeable in object and material view when we go into rendered view our grease pencil strokes will be affected by lights. With this option, we can enable or disable that.
Each grease pencil layer has its own separate set of transform values. This is handy as though we already have a transform for the grease pencil object we can also move, rotate, and scale each of the layers in our grease pencil object separately.
We can also animate these transform values allowing us to move, scale, and rotate each layer separately.
Each layer has a relations tab that allows us to assign a parent object to the layer, we can also set the pass index here and or assign our grease pencil layer to a view layer.
With a parent object assigned, if we transform that parent object those transformations will be applied relative to the grease pencil layer. For example, if we move and scale our parent object the grease pencil layer will also be moved and scaled.
Grease pencil layers open up many ways for us to modify and work with our grease pencil drawing. Layers allow us to change the order that our strokes are rendered, we can also disable the ordering change and use layers specifically for organizing.
On top of that, we have many options to customize and adjust each of our layers separately. Hopefully, this article has helped answer a few questions or given a few ideas for how to use grease pencil that we weren't aware of before.
Thank you for your time.