blender 2.8 2d animation draw over 3d object

By Antonio Vazquez

Leap 2016, I was playing effectually with Blender 2.77 grease pencil when I noticed a issues in the stroke filling, then I decided try to fix it and contribute to the Blender project. Since then, I have washed more than than 1,100 commits for grease pencil as a volunteer and I think it'south fourth dimension to write my outset blog entry.

Grease pencil has something very special, because you demand to keep the feeling of a second animation inside a 3D surround, integrating these ii worlds smoothly. Just this challenge makes more exciting to work in an area that tin modify how 2d animation volition work in the futurity.

Christmas is effectually the corner and the Hero open movie directed by Daniel K. Lara is on production for several weeks already, working in a daily ground with the Grease Pencil branch.

Working in a existent production is the best way to fine tune a software and find the real artistic requirements as well every bit to polish workflows. Therefore the Hero open movie is a perfect way to amend grease pencil.

During these weeks the Hero team has requested a lot of new features and adjustments to arrange grease pencil to the production workflow. Sometimes the changes were simple modifications of default values merely other times the changes were bigger like the multi frame editing falloff.

Allow's review some of these new features and changes we take been working on. Thanks to Daniel Lara and Matias Mendiola for providing the demonstration videos of this commodity.

Multi frame editing falloff

When yous are doing a second blitheness, it's very mutual to need to redraw or touch several frames in guild to get a smooth blitheness. You usually utilise the onion skinning available (I added support for more onion skinning modes too). The problem with onion skinning is that you can only "come across" the blitheness, but you cannot edit the drawings.

The Hero team requested a way to change multiple frames at the same time, so I adult a new multi frame edition way that allows changing several frames at the same time. Yous can select the frames affected using the Dopesheet. This multi frame edition saves a lot of fourth dimension to animators.

Afterwards thinking about the problem, Daniel came with the thought of a falloff event. A few tests after, and I implemented a manner to calculate a shine transition for sculpted frames. Now, if you lot motion the stroke some units in the electric current frame, the previous and next selected frames will also be afflicted, based on an interpolation bend.

With this arroyo you can get smooth transitions. And by adjusting the interpolation curve, a slow in/out issue can be now easily achieved.

Modifiers

Modifiers are something nosotros apply everyday in 3D, but it's something totally new in grease pencil.

The first footstep to implement this for grease pencil was to determine how to reuse the electric current infrastructure, while customizing it to the 2d requirements. I did an initial design and after a lot of trial and fault, I got something that worked, but after some review by other developers, the initial pattern required some changes to go along improve aligned with the general Blender modifiers design. Finally, with the help of Joshua (Leung), we got a better design and implementation.

This is the electric current list of the new modifiers.

Grease pencil has some special requirements that could exist handled with modifiers. In some cases, yet, the modifier was non modifying the stroke backdrop, every bit all 3D meshes modifiers practise, but changing their look only.

To solve this "look only" modifiers, I designed the VFX modifiers, that work in a similar way to the Eevee viewport effects, affecting the look of the image of the grease pencil object. This is done using a total screen shader that works as a filter for the epitome. The VFX modifiers tin can be different for each object, so nosotros can activate VFX blur for one object while keeping other objects sharp.

VFX Light

Since I started to develop for grease pencil, one of my first idea was to add together some type of lighting support.

Lighting is a circuitous topic, peculiarly when you lot are working with 2d elements in a 3D world. In 2nd, the concepts of normals, faces then on changes a little, and then you need to find a way to mimic all these things in a 2D environs.

Every bit real lighting was out of scope at this moment (it would require more work on Eevee which has its own priorities at the moment), I decided to implement some way of 2d lighting using a special VFX shader.

VFX can be applied to a single object and get cool effects, but this lighting has no relation with other objects. In the hereafter, a total Eevee integration of grease pencil could be implemented, only for now, something is improve than cypher.

The master problem in the evolution was how to manage the lite position and how to convert this to the 2d world. Finally, I got an algorithm to calculate the distance to an "invisible" plane represented by the strokes and afterwards some debugging I got a adept consequence.

Build modifier

Build modifier is something all animators want. Here Joshua comes with a great implementation.

The build modifier allows to animate the drawing of the strokes in a similar fashion of the Build modifier for 3D objects.

Simplify modifier

The simplify process was something yous call back is necessary from the offset stages of the design, but it was one that shows how important it is to have real talented artists working in the development procedure.

The initial idea of this modifier was to apply the aforementioned algorithm that I've used in my grease pencil add-on last year. I was investigating and the most used i was the Ramer–Douglas–Peucker algorithm. This algorithm takes a line and simplify it keeping as much as possible of the original shape.

The first implementation of the modifier worked using the RDP algorithm, just after several weeks, the Hero squad requested a more unproblematic mode of "cleaning" the drawings, so I had to implement a unproblematic way to remove a indicate for every 2 points. Finally, I added a parameter to apply recursively the stock-still simplify logic to speed up cleaning.

This new simplify fixed mode was something that as developer I have never thought, but for artists, it shows upwardly as a natural requirement for production workflow.

Offset modifier

To be able to move some strokes of the same object in a gratis way was something that came to my mind thinking in how to motility the eyebrows of a character without affecting other areas.

To solve tasks like this, the offset modifier is a keen tool because you lot tin filter by layer, pass index or vertex group, then y'all can apply any blazon of transformation to selected areas of the drawing or create absurd furnishings equally showed in the post-obit video.

Update: Shader FX

Other changes

There were a lot of things that were modified during these by weeks that are non visible simply accept a lot of impact. Hither, Joshua did a great job refactoring the code to use the new depsgraph and marshal some parts to exist ready to merge with 2.eight branch. I know these are not fancy areas, just we must cheers Joshua for his first-class work again. It's never too much to remind that he is the original programmer of grease pencil in Blender, and none of this would be possible without his piece of work.

When?

Blender 2.viii beta in August! If you lot compile Blender yourself, you can already try the new Grease Pencil, as it is currently being developed on separate branches (the main ane being greasepencil-object).

We have done more things, and keep improving it every day. Stay tuned for more news!

Cheers,
Antonio

Grease Pencil Developers:
Antonio Vazquez (@antonioya_blend)
Joshua Leung (@aligorith)

Artists:
Daniel M. Lara (@_pepeland_)
Matias Mendiola (@mmendio)

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Source: https://code.blender.org/2017/12/drawing-2d-animation-in-blender-2-8/