From b397e2517b0d785368c9dcee4e24bfc86526799a Mon Sep 17 00:00:00 2001 From: lmj01 Date: Fri, 6 Sep 2024 17:31:38 +0800 Subject: [PATCH] update --- cg/graphics.md | 2 ++ cg/lighting/illumination.model.md | 52 +++++++++++++++++++++++++++++ cg/lighting/{light.md => lights.md} | 0 cg/lighting/pbr.md | 4 --- cg/mesh/mesh.triangle.md | 34 +++++++++++++++++-- cg/threejs/use.md | 2 +- cg/tools/galacean.md | 5 +++ cg/tools/webgl.md | 1 + exercises/math.secondary.md | 22 ++++++++++++ index/community.md | 7 +++- index/computerScience.md | 3 ++ 11 files changed, 124 insertions(+), 8 deletions(-) create mode 100644 cg/lighting/illumination.model.md rename cg/lighting/{light.md => lights.md} (100%) delete mode 100644 cg/lighting/pbr.md create mode 100644 cg/tools/galacean.md diff --git a/cg/graphics.md b/cg/graphics.md index bbd58c0..1969c3f 100644 --- a/cg/graphics.md +++ b/cg/graphics.md @@ -3,6 +3,8 @@ - [Khronos社区](https://community.khronos.org/) - [threejs社区](https://discourse.threejs.org/) +- [光照模型](/cg/lighting/illumination.model.md) + 早期3D的API由驱动层提供，所有细节都是驱动贴近硬件实现的，在经过shader发展中，现代硬件越来越复杂了 新时代的抽象图形接口vulkan来了，需要更具象化的过程，就是需要自己负责更多的事情 - 任务调度 diff --git a/cg/lighting/illumination.model.md b/cg/lighting/illumination.model.md new file mode 100644 index 0000000..7f8c992 --- /dev/null +++ b/cg/lighting/illumination.model.md @@ -0,0 +1,52 @@ +# 光照模型 + +Illumination model, also known as Shading model or Lighting model, is used to calculate the intensity of light that is reflected at a given point on surface. + +依赖三个元素 +- Light Source : Light source is the light emitting source. + - Point Sources + - Parallel Sources + - Distributed Sources +- Surface : When light falls on a surface part of it is reflected and part of it is absorbed. +- Observer : The observer’s position and sensor spectrum sensitivities also affect the lighting effect + + +## 基础光照模型 + +### Ambient Illumination + +$$ +I_{amb} = K_{a}I_{a} \newline +I_{a} \text{ambient light intensity}, K_{a} \text{ surface ambient reflectivity } \in [0,1] +$$ + +### Diffuse Reflection + +$$ +I_{diff} = K_{d}I_{p}cos\theta = K_{d}I_{p}(N \dot L) \newline +I_{p} \text{the point light intensity}, K_{d} \text{ surface diffuse reflectivity } \in [0,1], \newline +N \text{the surface normal}, L \text{the light direction} +$$ + +- Normals in geometry a normal is a vector or a line that is perpendicular to a given object (e.g. plane normal, vertex normal ). + - 用于光照计算，如Diffuse reflection漫反射 + +### Specular Reflection + +$$ +I_{spec} = W(\theta)I_{I}cos^{n}(\phi) = K_{s}I_{I}cos^{n}(\phi) \newline +N \text{the surface normal}, L \text{the light direction} \newline +R \text{direction of reflected ray}, V \text{direction of observer} \newline +\theta \text{angle between L and R}, \phi \text{angle between R and V} \newline +$$ + +## 物理渲染模型 + +### Physically Based Rendering + +[Monte Carlo Integration](https://64.github.io/monte-carlo/) + + +## 参考 + +- [Basic Illumination Models](https://www.geeksforgeeks.org/basic-illumination-models/) \ No newline at end of file diff --git a/cg/lighting/light.md b/cg/lighting/lights.md similarity index 100% rename from cg/lighting/light.md rename to cg/lighting/lights.md diff --git a/cg/lighting/pbr.md b/cg/lighting/pbr.md deleted file mode 100644 index 774fe84..0000000 --- a/cg/lighting/pbr.md +++ /dev/null @@ -1,4 +0,0 @@ -# Physically Based Rendering - -[Monte Carlo Integration](https://64.github.io/monte-carlo/) - diff --git a/cg/mesh/mesh.triangle.md b/cg/mesh/mesh.triangle.md index 0f7f77c..d1272e1 100644 --- a/cg/mesh/mesh.triangle.md +++ b/cg/mesh/mesh.triangle.md @@ -1,5 +1,6 @@ # 三角面片 +- [重新审视褶皱表面的模拟](http://image.diku.dk/projects/media/morten.mikkelsen.08.pdf) ## Normal @@ -10,13 +11,15 @@ ## Tangent +切线空间是一个局部坐标系，原点就是vertex顶点位置，通常Z轴与顶点的法线对齐，X轴由顶点的切线Tangent、y轴由顶点的副切线Bitangent定义。 + +- [Lesson 6bis: tangent space normal mapping](https://github.com/ssloy/tinyrenderer/wiki/Lesson-6bis:-tangent-space-normal-mapping) + ### per-vertex tangent spaces - [Computing Tangent Space Basis Vectors for an Arbitrary Mesh](https://terathon.com/blog/tangent-space.html) - [课件](https://www.cs.upc.edu/~virtual/G/index.php?dir=) - [pdf](https://www.cs.upc.edu/~virtual/G/1.%20Teoria/06.%20Textures/Tangent%20Space%20Calculation.pdf) -- [threejs的Tangent支持](https://threejs.org/docs/#examples/en/utils/BufferGeometryUtils.computeMikkTSpaceTangents) -
顶点切线的数学推理 @@ -89,6 +92,27 @@ $$
+#### [threejs的Tangent支持](https://threejs.org/docs/#examples/en/utils/BufferGeometryUtils.computeMikkTSpaceTangents) +```c +#ifdef USE_TANGENT +attribute vec4 tangent; +#endif +vec3 objectTangent = vec3( tangent.xyz ); +// src\renderers\shaders\ShaderChunk\normal_pars_fragment.glsl.js +// src\renderers\shaders\ShaderChunk\normal_pars_vertex.glsl.js +varying vec3 vTangent; +varying vec3 vBitangent; +// src\renderers\shaders\ShaderChunk\defaultnormal_vertex.glsl.js +vec3 transformedTangent = objectTangent; // 变形的影响 +// src\renderers\shaders\ShaderChunk\normal_vertex.glsl.js +vTangent = normalize( transformedTangent ); +vBitangent = normalize( cross( vNormal, vTangent ) * tangent.w ); +// src\renderers\shaders\ShaderChunk\normal_fragment_begin.glsl.js +mat3 tbn = mat3( normalize( vTangent ), normalize( vBitangent ), normal ); +// src\renderers\shaders\ShaderChunk\normal_fragment_maps.glsl.js +normal = normalize( tbn * mapN ); +``` + ### MikkTSpace - [Tangent Space Normal Maps](http://www.mikktspace.com/) - [github c](https://github.com/mmikk/MikkTSpace) @@ -97,4 +121,10 @@ $$
MikkTSpace切线的数学推理 +MikkTSpace的方案成了事实上的标准，blender就用它来生成Normal Mapping的，光照计算中也是一个非常角色。 +MikkTSpace生成tangent space即使改变了点索引，面的顺序，删除primitive等等都不影响且对triangles和quads都支持的。 + +顶点必须具有属性：位置Position，法线Normal，纹理坐标UV + +
diff --git a/cg/threejs/use.md b/cg/threejs/use.md index c01be5e..e78781f 100644 --- a/cg/threejs/use.md +++ b/cg/threejs/use.md @@ -66,7 +66,7 @@ camera的近远曲线的趋势。 牙龈根据关键点生成了面片数据，包含了顶点、uv、索引。 前端对生成的数据进行了处理，处理顶点法线，position,uv,normal,tangent。 -又根据uv和tangent算出了一个uv2和tangent2. 至于为什么有这样的逻辑？忙猜是逆向过程中看到这样的逻辑。 +又根据uv和tangent算出了一个uv2和tangent2. 大致逻辑是拷贝，处理相同点的问题，在shader中取tangent和tangent2的均值作为最终值来使用。 ### flickering 2024-7-19 diff --git a/cg/tools/galacean.md b/cg/tools/galacean.md new file mode 100644 index 0000000..cf848b5 --- /dev/null +++ b/cg/tools/galacean.md @@ -0,0 +1,5 @@ +# [Galacen](https://galacean.antgroup.com/engine/) + +阿里系下的一个webgl引擎，号称性能很好，研究一下源码看看核心的功能 +分析一下shader的代码逻辑 + diff --git a/cg/tools/webgl.md b/cg/tools/webgl.md index 6c9642d..46febcb 100644 --- a/cg/tools/webgl.md +++ b/cg/tools/webgl.md @@ -6,6 +6,7 @@ - [笔记](/cg/threejs/index.md) - [BabylonJS](https://www.babylonjs.com/) - [笔记](/cg/babylonjs/index.md) +- [galacean笔记](/cg/tools/galacean.md) ## [WebGL API](https://developer.mozilla.org/en-US/docs/Web/API/WebGL_API) diff --git a/exercises/math.secondary.md b/exercises/math.secondary.md index 4055216..5f41e3d 100644 --- a/exercises/math.secondary.md +++ b/exercises/math.secondary.md @@ -33,6 +33,28 @@ $e^{\pi i} + 1 = 0 \to e^{\pi i} = -1$ +## 代数 + +### 代数式 + +#### 对称式 + +如果交换一个代数式中任意两个字母的位置，所得代数式和原代数式恒等，那么成代数式为对称式。 + +#### 轮询式 + +把一个代数式中的字母按照某个秩序排列，然后依次把第一个字母换成第二个字母，第二个字母换成第三个字母，……，最后一个字母换成第一个字母，依次轮换一圈后，所得的代数式与原代数式恒等，则称这个代数式为轮换式 + +- 对称式一定是轮询式 +- 轮询式不一定是对称式 +- 轮换对称式的和、差、积、商也是轮换对称式 + +##### 齐次轮换对称式 + +如果轮换对称式中各项的次数相等，那么就把这样的代数式叫做齐次轮换对称式. 具有一下属性，对因式分解非常有帮助 + +- 齐次轮换对称式的和、差、积、商也是齐次轮换对称式 + ## 几何
diff --git a/index/community.md b/index/community.md index 6d14ce5..51e56df 100644 --- a/index/community.md +++ b/index/community.md @@ -83,4 +83,9 @@ languages including common scripting languages such as Javascript, Perl, PHP, Py - [这是一款开源、多语言、自托管的项目管理工具，兼容了 Trello 和 Notion 的特点](https://www.focalboard.com/) - [github](https://github.com/mattermost/focalboard) -- [款开源、安全、跨平台的密码管理器。该项目是采用 C++ 开发的免费、离线、无广告的密码管理工具](https://github.com/keepassxreboot/keepassxc) \ No newline at end of file +- [款开源、安全、跨平台的密码管理器。该项目是采用 C++ 开发的免费、离线、无广告的密码管理工具](https://github.com/keepassxreboot/keepassxc) + +## 社区 + +- [Khronos Standards community discussions github-account](https://community.khronos.org/) +- [The three.js community discourse. github-account](https://discourse.threejs.org/) \ No newline at end of file diff --git a/index/computerScience.md b/index/computerScience.md index 26c2b18..2a4b670 100644 --- a/index/computerScience.md +++ b/index/computerScience.md @@ -16,6 +16,8 @@ - [Zig is a general-purpose programming language and toolchain for maintaining robust, optimal and reusable software.](https://ziglang.org/) - [core analyzer -- A power tool to understand memory layout](https://core-analyzer.sourceforge.net/index_files/Page525.html) +- [Numerical Computation Guide](https://docs.oracle.com/cd/E19957-01/806-3568/ncgTOC.html) + - [What Every Computer Scientist Should Know About Floating-Point Arithmetic](https://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html) ### Database @@ -66,6 +68,7 @@ - [Bgfx](/cg/bgfx.md) - [UI](/cg/ui.md) - [threejs 笔记](/cg/threejs/index.md) +- [Galacean](/cg/galacean/index.md) ### 动画