less_retarded_wiki/3d_model.md

# 3D Model

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## 3D Modeling: How To Learn And Do It Well

WORK IN PROGRESS

Nowadays as a [FOSS](foss.md) user you will most likely do 3D modeling with [Blender](blender.md) -- we recommended it to start learning 3D modeling as it is powerful, [free](free_software.md), gratis, has many tutorials etc. Do NOT use anything [proprietary](proprietary.md) no matter what anyone tells you! Once you know a bit about it, you may try alternative programs (as Blender still has its flaws) or approaches (such as writing programs that generate 3D models etc.). However **as a beginner just start with Blender**, which is from now on in this article the software we'll suppose you're using.

**Start extremely simple and learn bottom-up**, i.e. learn about fundamentals and low level concepts and start with very simple models (e.g. simple untextured low-poly shape of a house, box with a roof), keep creating more complex models by small steps. Do NOT fall into the trap of "quick and easy magic 3D modeling" such as sculpting or some "[smart](smart.md) [apps](app.md)" without knowing what's going on at the low level, you'll end up creating extremely ugly, inefficient models in bad formats, like someone wanting to create space rockets without learning anything about math or physics first. Remember to **practice, practice, practice** -- eventually you learn by doing, so try to make small projects and share your results on sites such as opengameart to get feedback and some mental satisfaction and reward for your effort. The following is a possible path to learning 3D modeling well:

1. **Learn what 3D model actually is, how a computer represents it and roughly how [3D rendering](3d_rendering.md) works**. It is EXTREMELY important to have at least the very basic knowledge of the fundamentals, i.e. you should learn at least the following:
  - 3D models that are used today consist of **vertices and [triangles](triangle.md)** (though higher polygons are usually supported in modeling software, everything is broken down to triangles eventually), computers usually store [arrays](array.md) of vertices and triangles as indices pointing to the array of vertices. Triangles have **facing** (front and back side, determined by the order of its vertices). These 3D models only represent the boundary (not the volume). These are called the model's **geometry**.
  - **[Normals](normal.md)** are [vectors](vector.md) "perpendicular to the surface", they can be explicitly modified and stored or computed automatically and they are extremely important because they say how the model interacts with light (they are used in [shading](shading.md) of the model), i.e. which edges appear sharp or smooth. Normal maps are textures that can be used to modify normals to make the surface seem rough or otherwise deformed without actually modifying the geometry.
  - **[Textures](texture.md)** are images (or image-like data) that can be mapped to the model surface to "paint it" (or give it other material properties). They are mapped to models by giving vertices texturing **UV coordinates**.
  - 3D rendering (and also modeling) works with the concept of a **[scene](scene.md)** in which a number of models reside, as well as a virtual camera (or multiple ones), lights and other objects. These objects have transformations (normally translation, rotation and scale) and may form a hierarchy (some objects may be parents of other objects, meaning the child transformations are relative to parents) etc.
  - A 3D renderer will draw the triangles the model consists of by applying **[shading](shading.md)** to determine color of each [pixel](pixel.md) of the triangle. Shading takes into account besides others texture(s) of the model, its material properties and light falling on the model (in which the model normals play a big role). Shading can be modified by creating **[shaders](shader.md)**.
  - Learn about other concepts such as low/high poly modeling and basic 3D formats such as [OBJ](obj.md) and [COLLADA](collada.md) (which features they support etc.), possible other models representations ([voxels](voxel.md), [point clouds](point_cloud.md), ...).
2. **Manually create a few extremely simple [low-poly](low_poly.md) untextured models**, e.g. that of a simple house, laptop, hammer, bottle etc. Keep the vertex and triangle count very low (under 100), make the model by MANUALLY creating every vertex and triangle and focus only on learning this low level geometry manipulation well (how to create a vertex, how to split an edge, how to rotate a triangle, ...), making the model conform to good practice and get familiar with tools you're using, i.e. learn the key binds, locking movement direction to principal axes, learn manipulating your 3D view, setting up the free/side/front/top view with reference images etc. Make the model nice! I.e. make it have correctly facing triangles (turn backface culling on to check this), avoid intersecting triangles, remove all duplicate vertices (don't have multiple vertices with the same position), connect all that should be connected, avoid badly shaped triangles (e.g. extremely acute/long ones) etc. Also learn about normals and make them nice! I.e. try automatic normal generation (fiddle e.g. with angle thresholds for sharp/smooth edges), see how they affect the model look, try manually marking some edges sharp, try out smoothing groups etc. Save your final models in OBJ format (one of the simplest and most common formats supporting all you need at this stage). All this will be a lot to learn, that's why must not try to create a complex model at this stage. You can keep yourself "motivated" e.g. by aiming for creating a low-poly model collection you can share at opengameart or somewhere :)
3. **Learn texturing** -- just take the models you have and try to put a simple texture on them by drawing a simple image, then unwrapping the UV coordinates and MANUALLY editing the UV map to fit on the model. Again the goal is to get familiar with the tools and concepts now; experiment with helpers such as unwrapping by "projecting from 3D view", using "smart" UV unwrap etc. Only make a simple diffuse texture (don't do [PBR](pbr.md), material textures etc., that's too advanced now).
4. **Learn modifiers and advanced tools**. Modifiers help you e.g. with the creation of symmetric models: you only model one side and the other one gets mirrored. Subdivide modifier will automatically create a higher poly version of your model (but you need to help it by telling it which sides are sharp etc.). [Boolean](bool.md) operations allow you to apply set operations like unification or subtraction of shapes (but usually create a messy geometry you have to repair!). There are many tools, experiment and learn about their pros and cons, try to incorporate them to your modeling.
5. **Learn retopology and possibly sculpting**. Topology is an extremely important concept -- it says what the structure of triangles/polygons is, how they are distributed, how they are connected, which curves their edges follow etc. Good topology has certain rules (e.g. ideally only being composed of quads, being denser where the shape has more detail and sparser where it's flat, having edges so that animation won't deform the model badly etc.). Topology is important for efficiency (you utilize your polygon budget well), texturing and especially animation (nice deformation of the model). Creating more complex models is almost always done in the following two steps:
  1. Creating the shape while ignoring topology, for example with sculpting (but also other techniques, e.g. just throwing shapes together). The goal is to just make the desired shape.
  2. Retopology: creating a nice topology for the shape while keeping the shape unchanged. This is done by starting modeling from the start with the "stick to surface" option, i.e. whenever you create or move a vertex, it sticks to the nearest surface (surface of the created shape). Here you just try to create a new "envelope" on the existing shape while focusing on making the envelope's topology nice.
6. **Learn about materials and [shaders](shader.md)**. At this point you may learn about how to create custom shaders, how to create transparent materials, apply multiple textures, how to make realistic skin, [PBR](pbr.md) shaders etc. You should at least be aware of basic shading concepts and commonly encountered techniques such as [Phong shading](phong_shading.md), [subsurface scattering](subsurface_scattering.md), [screen space](screen_space.md) effects etc. because you'll encounter them in shader editors and you should e.g. know what performance penalties to expect.
6. **Learn animation**. First learn about keyframes and [interpolation](interpolation.md) and try to animate basic transformations of a model, e.g. animate a car driving through a city by keyframing its position and rotation. Then learn about animating the model's geometry -- first the simple, old way of morphing between different shapes (shape keys in Blender). Finally learn the hardest type of animation: skeletal animation. Learn about bones, armatures, rigging, inverse kinematics etc.
7. **Now you can go crazy** and learn all the uber features such as hair, physics simulation, [NURBS](nurbs.md) surfaces, boob physics etc.