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40c0886 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 | # Unity Rendering
## Materials and Shaders
A **Material** is an asset that defines how a surface is rendered. It
references a **Shader** (the GPU program) and sets its properties (colors,
textures, numbers).
Unity 2022 ships the following built-in shaders worth knowing:
| Shader | Use case |
|-------------------|---------------------------------------------------------|
| `Standard` | The default PBR shader -- metal/smoothness workflow |
| `Universal Render Pipeline/Lit` | URP equivalent of Standard |
| `Unlit/Texture` | Pure textured quad, no lighting |
| `Sprites/Default` | 2D sprites |
| `UI/Default` | Canvas UI Image |
The generated project uses the Built-in Render Pipeline (not URP) so that
the agent can rely on `Shader.Find("Standard")` without any package setup.
### Procedural materials
```csharp
var mat = new Material(Shader.Find("Standard"));
mat.name = "ProceduralWater";
mat.color = new Color(0.2f, 0.6f, 0.8f, 0.7f);
mat.SetFloat("_Glossiness", 0.85f);
mat.SetFloat("_Metallic", 0.1f);
mat.EnableKeyword("_EMISSION");
mat.SetColor("_EmissionColor", new Color(1f, 0.85f, 0.4f));
mat.renderQueue = 3000; // transparent
GetComponent<MeshRenderer>().sharedMaterial = mat;
```
* `_Color`, `_MainTex`, `_Glossiness`, `_Metallic`, `_EmissionColor` are the
Standard shader's main properties.
* Call `EnableKeyword("_EMISSION")` before setting `_EmissionColor`.
* For transparent materials set `_Mode` to 3 (Transparent) and configure
blend modes as in the `WaterMaterial.cs` generator.
## Lighting
* **Directional light** -- simulates the sun. Rotating it changes time of
day. The `DayNightCycle.cs` generator does exactly this.
* **Point light** -- radiates in all directions; cost is proportional to
the number of pixels it touches. Use sparingly on mobile.
* **Spot light** -- cone shape; useful for flashlights, street lamps.
* **Area light** -- only baked; good for indoor ceilings.
**Realtime vs Baked:** static geometry should use **baked** lighting
(Lightmap) for performance; dynamic objects use realtime lighting.
```csharp
Light l = gameObject.AddComponent<Light>();
l.type = LightType.Point;
l.color = Color.white;
l.intensity = 1.5f;
l.range = 15f;
l.shadows = LightShadows.Soft; // softest, but most expensive
```
## Skybox and ambient
* The skybox is set via `RenderSettings.skybox` or `Window > Rendering > Lighting > Environment`.
* `RenderSettings.ambientLight` controls flat ambient color when
`RenderSettings.ambientMode = AmbientMode.Flat`.
* The `DayNightCycle` generator lerps both `ambientLight` and
`Camera.main.backgroundColor` between day/night colors.
## Post-processing (Built-in Pipeline)
Post-processing is provided by the `com.unity.postprocessing` package. Add a
`Post-process Layer` to the Main Camera and a `Post-process Volume` to the
scene to drive effects such as Bloom, Color Grading, Depth of Field,
Vignette and Motion Blur.
```csharp
// You usually configure post-processing in the inspector rather than code.
// Make sure the camera has a PostProcessLayer and a global PostProcessVolume.
```
## LOD (Level of Detail)
Use `LODGroup` to swap meshes based on distance. Unity picks the LOD level
based on the screen-space size of the bounding box.
```
LOD 0 -- 60%+ screen size -- high-poly mesh
LOD 1 -- 30%-60% -- medium
LOD 2 -- 10%-30% -- low
Cull -- <10% -- not rendered
```
For procedural cities, prefer instancing (`Graphics.DrawMeshInstanced`) or
`LODGroup` over spawning 50+ full-detail buildings.
## Fog
```csharp
RenderSettings.fog = true;
RenderSettings.fogMode = FogMode.Linear;
RenderSettings.fogColor = new Color(0.5f, 0.5f, 0.5f, 1f);
RenderSettings.fogStartDistance = 50f;
RenderSettings.fogEndDistance = 300f;
```
Fog hides the far clip plane pop-in and is essential for large open worlds.
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