Intro to Topology
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Everything below represents notes for Sepha to finish the YouTube vid and article with.
MORE THEORY LOL
Actually make and record this all as a video, because the content is pretty dry.
What is "Topology"?
The art of topology is creating a mesh which has specific desired secondary characteristics.
How we define the surface of our mesh will impart intangible secondary characteristics into that mesh, and allows it to be capable of certain behaviors.
Take this contrived human face for example. It has perfectly fine mesh integrity, but otherwise horrible topology:
It's bad in numerous ways, but I've indicated two with the dotted lines. No matter how these edges are pushed or pulled, the geometry is simply incapable of achieving a smile or a frown. And we know that most human faces we make will need to at least smile and frown.
The following face however, CAN support frowns and smiles, because the edges are laid out in a way that naturally allows them to contract and pinch around those areas.
Note - Conceptually topology exists in a separate space from Mesh Integrity, even though they are deeply related. Mesh Integrity is not negotiable, topology is subjective and goal oriented.
Good Topology is goal based.
Our Meshes will often need to do several things, sometimes several at once:
Animation: Our Meshes may need to bend, and deform. They cannot bend and deform predictably or believably if their surface topology can't support it.
Sculpting: A mesh might need to be sculpted upon, and so our topology should concentrate detail where we need it, and not work against us to disrupt our brush strokes (poles)
Subdivision Modeling: The mesh may need to support edge loops, with clean subdivision workflow centric loops and rings.
Normal Maps and shading: The mesh (commonly the lowpoly) will often need to render its normals, and interact with a normal map
The topological requirements of normal map rendering are very specific.
Create Bakes: Our bakes (when we get to them) will depend upon our surface shading and normal, and we use Topology to manipulate this.
Rendering Efficiency: Our meshes will need to render in real time, and so use as little triangles as we need.
Speed and Budget: We will need to physically make our own meshes, so speed and time are also factors - some topology is very slow to create, while other topology slows down our box modeling speed.
Teamwork and Collaboration: Our meshes will need to be handed to other team mates, and so short cuts we take topologically can have a compounding effect on the team.
VFX or Simulation: Our meshes may need to be used in VFX, Film, or for Simulation, which will have specific and stringent requirements of its topology
Key Insight 1: There is simply no once size fits all "Good Topology".
Key Insight 2: The requirements placed on our Highpolys are vastly different than the requirements placed on our Lowpolys.
Example #1
This is an example of a Lowpoly P90 and Normal Map bake that I have created:
And here is its wireframe:
This is an example of great topology, even though it goes against several common misconceptions.
The goals of this mesh:
Use as few triangles as is required.
Be non deforming.
Create and Render a normal map, for a current gen game engine.
Ideally be made as fast as possible.
The mesh achieves all of those objectives, with no corresponding downsides. It does not need to deform, it is not a sculpt mesh, and in general uses as few triangles as needed.
Example #2
A human face however, is very different. Infact most organic deforming surfaces will be.
The goals of this human face:
Provide geometry which is friendly to sculpting
Animate and deform, support all of the common movements of the human face
Allow for ease of skinning and weight painting.
Create and Render a normal map, for a current gen game engine.
Because the objectives of the two meshes are wildly different, their respective topologies will also be wildly different.
SEPHA TODO:
Give an example of sculpt topology, strengths and weaknesses
Give an example of hard surface topology that wastes triangles, and why its bad
Showcase
Practise makes perfect
As you create more and more models, you will naturally come to understand when your topology is sufficient, and when it isn't.
Try not to be ultra concerned about it at the moment, and use a common sense approach. We will explore more in-depth topological concepts over the course.
Always be asking yourself: "Can this mesh do what it need it to do?"
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