I am trying to create shading similar to this, where the shading is spikey, how would I go about doing that in illustrator?
Yes as the comments said, the only way yet is to Draw Spikey! But in my opinion the best Tool is Pencil Tool.
- Make a copy in front of your main object (here you have petals).
- Then start editing them by redraw the boundaries of the object inside and shape your desired illustration (make sure "Edit selected path" is enabled in Pencil Tool Options (double click on tool icon to bring options)). *** The step two is the key to quality, it depends on your experience on using a Mouse (like me) or a Pressure Pen.
- Recolor your redrawn object lighter or darker for highlight or shadow effect.
*** For more details repeat the steps above for created new shadow or highlight objects.
You really do not want especially little. The spiky patterns have 2 roles:
They present the curvature of the assumed 3D surface. To do it they must be plausible projections "like they were drawn on a curved surface"
In big picture they also present the brightness variations, the shading, as you have already said.
Image engravers met the same problems as soon as image printing plates became popular. Deciding and carving the wanted curves which fulfill both demands and were possible to make needed and still needs specially talented persons who refined their skills years. Drawing in a computer what you want is substantially easier because you can UNDO and retry one place as many times as you want. Engravers are productive only it they get it right straight in the fly.
As others have said much earlier, you must draw the patterns. Programs can give some shortcuts, but the taperings, curved forms and placements of the spikes must be decided by you. Let's try an example. I make it in Inkscape, because it has a little more flexible path drawing and editing tools (=pen, node tool) than Illustrator, at least my legacy version of Illustrator.
In the left there's an imagined curved surface. In the right I have drawn a complex path (=Bezier curve) which I believe to be good. The black spike pattern was drawn by clicking with the pen. It was like a saw blade.Straight line segments were pushed easily to curved with the node tool.
Its drawn bigger than the actual surface for good reasons:
- if it happens to be otherwise good one can easily clip the extras off by taking an intersection
- the extras drawn over the board will be needed later when blurring is used to check does the black shape generate a good shading in the big picture (=when one doesn't pay attention to individual spikes) The extras prevent transparency leaking from outside.
But is the curvature any good? To see better the black shape must be clipped to the size of the red surface and then one must fix the spikes, if needed.
In Inkscape one cannot adjust a shape under clipping mask. For that reason I made a group which contains only the black shape. That group got a duplicate of the red shape as a clipping mask:
The black shape can still be selected in the objects panel and it can be tweaked with the node tool. A couple of tweaks was made for less wrong curvature and to get one node on the left edge.
Does it make a good shading when watched as a part of bigger composition? It can be checked by blurring it temporarily. As said, the extras beyond the edge of the red shape prevent blurring to bring transparency from outside:
This is the effective shading caused by my black shape. The blur radius must be so high that the forms of the spikes fade and so low that no edge lightening happens over the surplus black area beyond the edge of the red shape.
If it's good, remove the blur. The complexity can be reduced by releasing the clipping mask, ungrouping and making an intersection between the red shape duplicate and the black shape:
Tweaking the curvatures of the spikes one by one is tedious. Illustrator has a way to draw arcs by clicking. It's the main content of one earlier answer (by Mr.Kerr) and its shown there perfectly. Another earlier answer used the pencil - that's a perfect method is one's hands and eyes are up to the task. Both methods need some real drawing skills when one creates a new original drawing.
Totally different way way to get curvatures easily is to use Envelope Distortion (Illustrator). Less drawing skills can be enough with it, but the ability to see the right forms is still a must.
In the top left I have a simple saw blade pattern and a rectangle.
In the top right I have use the rectangle as an envelope distortion top object. The saw blade and the rectangle are selected and Object > Envelope distort > Make with top object is applied. The same could be got by scaling and using Envelope Distort > Make with Mesh > 1 x 1.
In the bottom the corners of the generated distortion mesh are tweaked with the direct selection tool to 2 different distortion versions.
In theory one could increase the mesh complexity by adding more rows and columns or by using a more complex envelope top object. That unfortunately becomes easily unmanageable, so use simple envelopes. For me making a bigger one than 2 x 2 mesh has always been an effective way to get a reason to think again "why in the hell I didn't try this in 3D"
One can create the spike pattern curvature and the base shape curvature at the same time with envelope distortion. An example:
In the left there's a group of flat looking shapes. In the right they have got envelope distortion. I'm not claiming that a good looking flower scene where this could belong to exists, it only demonstrates what's possible.
Important to know:
The darkest red part covers actually also its both neighbors as a backround shape. That's because exactly fitting seams would leak the white background due the antialiasing and heavy bending easily doubles it due the roundings in the math.
One may wonder how in the hell could I decide beforehand the form of the pink part in the flat version so that it makes the hanging edge in the distorted version. I guessed it. To stay in truth it didn't succeed, but envelope distortion fortunately allows editing the flat shapes and seeing the distortion result in the fly. I deleted the not so well guessed flat shape and placed to the left a duplicate of the fixed version.
Basically, hold down Alt for corner points, and the curves should take care of themselves.
Carry on drawing all the lines, making sure to overlap the lines where they go over an edge
Once you have finished, select everything and make separate pieces using the Shape Builder tool. Hold down Alt and click to delete any overlapping lines. And finally fill the pieces of the design with the desired colour.