See the slider Optimizing PBR for mobile for more details

From ChatGPT

Specular Reflection: This component represents the mirror-like reflection where incident light rays reflect off the surface at the same angle as the incoming rays. In metallic surfaces, this specular reflection dominates due to the high conductivity of metals, causing most incident light to be immediately reflected.

Diffuse Reflection: Unlike non-metallic surfaces, where diffuse reflection is due to scattering from microscopic surface irregularities, the diffuse component in the Cook-Torrance model for metals often refers to the diffuse-like reflection caused by imperfections or micro-facets on the surface. These imperfections cause light to scatter in various directions rather than reflect perfectly specularly.

Refracted Light and Metals: Metals generally do not transmit light, so there is minimal refraction occurring within the material. Instead of transmitting through the surface, incident light on metals is typically reflected or absorbed due to the material's conductive properties. Therefore, the diffuse component in the Cook-Torrance model for metals does not originate from refracted light within the material but rather from surface imperfections that cause scattering.

Taking materials into consideration, so we could apply batching techniques

ScriptableRenderContext.ExecuteCommandBuffer copies commands to its own internal list from the buffer parameter

• MSAA keeps track of multiple samples per pixel, which don't have to be place in a regular grid.
• The fragment program is only invoked once per primitive per fragment, so at the original resolution. The result is then copied to all subsamples that are covered by the rasterized triangle.

i.e., if mulitple samples for a pixel locate in N primitives, the fragment program executes N times.

色调映射

See https://catlikecoding.com/unity/tutorials/custom-srp/directional-shadows/

However, directional lights are assumed to be infinitely far away and thus don't have a true position. So what we do instead is figure out view and projection matrices that match the light's orientation and gives us a clip space cube that overlaps the area visible to the camera that can contain the light's shadows.

Limit surface 极限表面

想象一下微积分中的求极限的过程，Limit surface 是求极限的结果

互斥量，互斥锁

higher overhead compared to other options

事务内存

数据竞争

以最快的速度去决定场景中哪些物体会与特定的光线相交，以此来避免计算那些不必要进行求交的测试

整型常量表达式

The cpu submit the vertex data and the array data containing per-object material properties once (single drawcall)

However, the GPU iterates all instances and draws them. (也就是说，一次 drawcall 期间，GPU 会绘制多次)

照片级的，照相写实主义的

菲涅尔-施利克 近似

水至于地形，类似于血液至于人体。

Fractal 的每个部分，无论放大还是缩小，它看起来都和整个图像类似。

例如树枝，树根。

The following blog simply introduces how "octatives" generate noise

https://blog.hirnschall.net/perlin-noise/

Tile Height Resolution - Height Resolution of the terrain tile we are creating.

Height Resolution - vertices in a row, vertices in a column. Terrains are generated by sampling heightmap with mesh vertices coordinates.

A PNG file data is not raw RGB24 data.

采样 Sampling

// glsl
col = texture(ourTexture, texcoord)
// hlsl
col = tex2D(ourTexture, texcoord)

OpenGL 使用纹理坐标来确定一个几何片段 fragment 在纹理贴图中的位置。然后使用 GL_NEAREST 或 GL_LINEAR 过滤操作对紧邻该位置的纹素进行采样。

slow start 慢启动 congestion avoidance 拥塞避免 fast retransmit 快速重传 fast recovery 快速恢复

gRPC 允许在同一个 gRPC 服务端运行多个 gRPC 服务，也允许多个客户端存根（stub）使用同一个客户端连接，这种功能叫做多路复用（multiplexing）。

https://www.jianshu.com/p/d8a6c7805717

模式、结构

Inversion of Control

控制反转

假设屏幕的宽 width 和高 height（像素）。

一般来说屏幕坐标的计算大概是这样

screenPos.x = ((pos.x/ pos.w) * 0.5 + 0.5) * width screenPos.y = ((pos.y/ pos.w) * 0.5 + 0.5) * height

稍微变换一下：

screenPos.x / width = ((pos.x/ pos.w) * 0.5 + 0.5) screenPos.y / height= ((pos.y/ pos.w) * 0.5 + 0.5)

两边再乘以 pos.w

screenPos.x / width * pos.w = (pos.x * 0.5 + pos.w * 0.5) <br/> screenPos.x / height * pos.w = (pos.y * 0.5 + pos.w * 0.5)

显然，右边的计算与 ComputeScreenPos 的核心计算是一样的。

也就是说 ComputeScreenPos 返回的坐标 * x: 范围 [0, w] * y: 范围 [0, w] * zw: 值同 pos.zw，因此这里 w 仍然存储着深度值

Rain Puddles 雨水坑 Puddle 水坑

享元模式

共享 intrinsic state 来减少内存占用

这个翻译也是满怪

URP 不支持 surface shader 了