[TOC]
大家好，本文根据领域驱动设计的成果，实现了init API。
# 上一篇博文
[从0开发3D引擎（十一）：使用领域驱动设计，从最小3D程序中提炼引擎（第二部分）](https://www.cnblogs.com/chaogex/p/12411575.html)
# 下一篇博文
[从0开发3D引擎（十三）：使用领域驱动设计，从最小3D程序中提炼引擎（第四部分）](https://www.cnblogs.com/chaogex/p/12418292.html#%E6%9C%AC%E6%96%87%E5%AE%8C%E6%95%B4%E4%BB%A3%E7%A0%81%E5%9C%B0%E5%9D%80)
# 继续实现
## 实现“DirectorJsAPI.init”
### 实现“保存WebGL上下文”限界上下文
1、在src/api_layer/api/中加入DirectorJsAPI.re，实现API
DirectorJsAPI.re代码为：
```re
let init = DirectorApService.init;
```
2、在src/infrastructure_layer/external/external_object/中加入Error.re，负责处理“js异常”这个外部对象
Error.re代码为：
```re
//根据错误信息(string类型)，创建并抛出“js异常”对象
let error = msg => Js.Exn.raiseError(msg);
//根据“js异常”对象，抛出它
let throwError: Js.Exn.t => unit = [%raw err => {|
throw err;
|}];
```
3、在src/application_layer/service/中加入DirectorApService.re，实现应用服务
DirectorApService.re代码为：
```re
let init = contextConfigJsObj => {
CanvasCanvasEntity.getCanvas()
|> OptionContainerDoService.get
//OptionContainerDoService.get函数返回的是Result容器的包装值，需要调用ResultContainerVO.bind函数来处理容器内部的值
|> ResultContainerVO.bind(canvas => {
SetWebGLContextSetWebGLContextDoService.setGl(
contextConfigJsObj,
canvas,
)
})
//应用服务DirectorApService负责用抛出异常的方式处理Result错误
|> ResultContainerVO.handleFail(Error.throwError);
};
```
关于bind函数的使用，可以参考[从0开发3D引擎（五）：函数式编程及其在引擎中的应用->bind](https://www.cnblogs.com/chaogex/p/12172930.html#bind)
4、修改CanvasCanvasEntity.re，实现getCanvas函数
CanvasCanvasEntity.re相关代码为：
```re
let getCanvas = () => {
Repo.getCanvas();
};
```
5、把最小3D程序的WebGL1.re放到src/infrastructure_layer/external/library/中，保留所有的代码
WebGL1.re代码为：
```re
open Js.Typed_array;
type webgl1Context;
type program;
type shader;
type buffer;
type attributeLocation = int;
type uniformLocation;
type bufferTarget =
| ArrayBuffer
| ElementArrayBuffer;
type usage =
| Static;
type contextConfigJsObj = {
.
"alpha": bool,
"depth": bool,
"stencil": bool,
"antialias": bool,
"premultipliedAlpha": bool,
"preserveDrawingBuffer": bool,
};
[@bs.send]
external getWebGL1Context:
('canvas, [@bs.as "webgl"] _, contextConfigJsObj) => webgl1Context =
"getContext";
[@bs.send.pipe: webgl1Context] external createProgram: program = "";
[@bs.send.pipe: webgl1Context] external useProgram: program => unit = "";
[@bs.send.pipe: webgl1Context] external linkProgram: program => unit = "";
[@bs.send.pipe: webgl1Context]
external shaderSource: (shader, string) => unit = "";
[@bs.send.pipe: webgl1Context] external compileShader: shader => unit = "";
[@bs.send.pipe: webgl1Context] external createShader: int => shader = "";
[@bs.get] external getVertexShader: webgl1Context => int = "VERTEX_SHADER";
[@bs.get] external getFragmentShader: webgl1Context => int = "FRAGMENT_SHADER";
[@bs.get] external getHighFloat: webgl1Context => int = "HIGH_FLOAT";
[@bs.get] external getMediumFloat: webgl1Context => int = "MEDIUM_FLOAT";
[@bs.send.pipe: webgl1Context]
external getShaderParameter: (shader, int) => bool = "";
[@bs.get] external getCompileStatus: webgl1Context => int = "COMPILE_STATUS";
[@bs.get] external getLinkStatus: webgl1Context => int = "LINK_STATUS";
[@bs.send.pipe: webgl1Context]
external getProgramParameter: (program, int) => bool = "";
[@bs.send.pipe: webgl1Context]
external getShaderInfoLog: shader => string = "";
[@bs.send.pipe: webgl1Context]
external getProgramInfoLog: program => string = "";
[@bs.send.pipe: webgl1Context]
external attachShader: (program, shader) => unit = "";
[@bs.send.pipe: webgl1Context]
external bindAttribLocation: (program, int, string) => unit = "";
[@bs.send.pipe: webgl1Context] external deleteShader: shader => unit = "";
[@bs.send.pipe: webgl1Context] external createBuffer: buffer = "";
[@bs.get]
external getArrayBuffer: webgl1Context => bufferTarget = "ARRAY_BUFFER";
[@bs.get]
external getElementArrayBuffer: webgl1Context => bufferTarget =
"ELEMENT_ARRAY_BUFFER";
[@bs.send.pipe: webgl1Context]
external bindBuffer: (bufferTarget, buffer) => unit = "";
[@bs.send.pipe: webgl1Context]
external bufferFloat32Data: (bufferTarget, Float32Array.t, usage) => unit =
"bufferData";
[@bs.send.pipe: webgl1Context]
external bufferUint16Data: (bufferTarget, Uint16Array.t, usage) => unit =
"bufferData";
[@bs.get] external getStaticDraw: webgl1Context => usage = "STATIC_DRAW";
[@bs.send.pipe: webgl1Context]
external getAttribLocation: (program, string) => attributeLocation = "";
[@bs.send.pipe: webgl1Context]
external getUniformLocation: (program, string) => Js.Null.t(uniformLocation) =
"";
[@bs.send.pipe: webgl1Context]
external vertexAttribPointer:
(attributeLocation, int, int, bool, int, int) => unit =
"";
[@bs.send.pipe: webgl1Context]
external enableVertexAttribArray: attributeLocation => unit = "";
"";
[@bs.send.pipe: webgl1Context]
external uniformMatrix4fv: (uniformLocation, bool, Float32Array.t) => unit =
"";
[@bs.send.pipe: webgl1Context]
external uniform1i: (uniformLocation, int) => unit = "";
[@bs.send.pipe: webgl1Context]
external uniform3f: (uniformLocation, float, float, float) => unit = "";
[@bs.send.pipe: webgl1Context]
external drawElements: (int, int, int, int) => unit = "";
[@bs.get] external getFloat: webgl1Context => int = "FLOAT";
[@bs.send.pipe: webgl1Context]
external clearColor: (float, float, float, float) => unit = "";
[@bs.send.pipe: webgl1Context] external clear: int => unit = "";
[@bs.get]
external getColorBufferBit: webgl1Context => int = "COLOR_BUFFER_BIT";
[@bs.get]
external getDepthBufferBit: webgl1Context => int = "DEPTH_BUFFER_BIT";
[@bs.get] external getDepthTest: webgl1Context => int = "DEPTH_TEST";
[@bs.send.pipe: webgl1Context] external enable: int => unit = "";
[@bs.get] external getTriangles: webgl1Context => int = "TRIANGLES";
[@bs.get] external getUnsignedShort: webgl1Context => int = "UNSIGNED_SHORT";
[@bs.get] external getCullFace: webgl1Context => int = "CULL_FACE";
[@bs.send.pipe: webgl1Context] external cullFace: int => unit = "";
[@bs.get] external getBack: webgl1Context => int = "BACK";
```
6、在srchttps://img.qb5200.com/download-x/domain_layerhttps://img.qb5200.com/download-x/domain/init/set_webgl_context/service/中加入SetWebGLContextSetWebGLContextDoService.re，创建领域服务SetWebGLContext
SetWebGLContextSetWebGLContextDoService.re代码为：
```re
let setGl = (contextConfigJsObj, canvas): ResultContainerVO.t(unit, Js.Exn.t) => {
ContextContextEntity.setGl(contextConfigJsObj, canvas)
|> ResultContainerVO.succeed;
};
```
7、修改ContextContextEntity.re，实现setGl函数
ContextContextEntity.re相关代码为：
```re
let setGl = (contextConfigJsObj, canvas) => {
ContextRepo.setGl(WebGL1.getWebGL1Context(canvas, contextConfigJsObj));
};
```
8、修改ContextPOType.re，定义Context PO的gl字段的数据类型
ContextPOType.re相关代码为：
```re
type context = {
gl: option(WebGL1.webgl1Context),
...
};
```
9、修改ContextRepo.re，实现仓库对Context PO的gl字段的操作
ContextRepo.re代码为：
```re
let getGl = gl => {
//将Option转换为Result
Repo.getContext().gl |> OptionContainerDoService.get;
};
let setGl = gl => {
Repo.setContext({...Repo.getContext(), gl: Some(gl)});
};
```
10、修改CreateRepo.re，实现创建Context PO的gl字段
CreateRepo.re相关代码为：
```re
let create = () => {
...
context: {
gl: None,
...
},
};
```
### 实现“初始化所有Shader”限界上下文
1、重写DirectorApService.re
DirectorApService.re代码为：
```re
let init = contextConfigJsObj => {
CanvasCanvasEntity.getCanvas()
|> ResultContainerVO.bind(canvas => {
SetWebGLContextSetWebGLContextDoService.setGl(
contextConfigJsObj,
canvas,
)
|> ResultContainerVO.bind(() => {InitShaderInitShaderDoService.init()})
})
|> ResultContainerVO.handleFail(Error.throwError);
};
```
2、加入值对象InitShader
在[从0开发3D引擎（十）：使用领域驱动设计，从最小3D程序中提炼引擎（第一部分）](https://www.cnblogs.com/chaogex/p/12408831.html)的“设计值对象InitShader”中，我们已经定义了值对象InitShader的类型，所以我们直接将设计转换为实现：
在srchttps://img.qb5200.com/download-x/domain_layerhttps://img.qb5200.com/download-x/domain/init/init_shader/value_object/中加入InitShaderInitShaderVO.re，创建值对象InitShader
InitShaderInitShaderVO.re代码为：
```re
type singleInitShader = {
shaderId: string,
vs: string,
fs: string,
};
type t = list(singleInitShader);
```
3、在srchttps://img.qb5200.com/download-x/domain_layerhttps://img.qb5200.com/download-x/domain/shader/shader/value_object/中加入ProgramShaderVO.re，创建值对象Program，它的DO对应一个WebGL的program对象
ProgramShaderVO.re代码为：
```re
type t =
| Program(WebGL1.program);
let create = program => Program(program);
let value = program =>
switch (program) {
| Program(value) => value
};
```
4、修改聚合根ShaderManager的DO
根据识别的引擎逻辑：
- 在初始化所有Shader时，创建每个Program
- 在渲染每个三角形时，根据Shader名称获得关联的Program
我们需要根据Shader id获得关联的Program，所以在ShaderManager DO中应该加入一个immutable hash map，它的key为Shader id，value为值对象Program的DO。
应该在领域视图的“容器”限界上下文中，加入值对象ImmutableHashMap、值对象MutableHashMap，其中ImmutableHashMap用于实现不可变的hash map，MutableHashMap用于实现可变的hash map。
现在来具体实现它们：
1)在srchttps://img.qb5200.com/download-x/domain_layerhttps://img.qb5200.com/download-x/domain/structure/container/value_object/中创建文件夹hash_map/
2)在hash_map/文件夹中加入ImmutableHashMapContainerVO.re、MutableHashMapContainerVO.re、HashMapContainer.re、HashMapContainerType.re
ImmutableHashMapContainerVO.re负责实现Immutable Hash Map；
MutableHashMapContainerVO.re负责实现Mutable Hash Map；
HashMapContainer.re从两者中提出的公共代码；
HashMapContainerType.re定义HashMap的类型。
因为HashMapContainer需要使用reduce来遍历数组，这个操作属于通用操作，应该作为领域服务，所以在领域视图的“容器”限界上下文中，加入领域服务Array。在srchttps://img.qb5200.com/download-x/domain_layerhttps://img.qb5200.com/download-x/domain/structure/container/service/中加入ArrayContainerDoService.re，创建领域服务Array。
相关代码如下：
ArrayContainterDoService.re
```re
let reduceOneParam = (func, param, arr) => {
//此处为了优化，使用for循环和mutable变量来代替Array.reduce
let mutableParam = ref(param);
for (i in 0 to Js.Array.length(arr) - 1) {
mutableParam := func(. mutableParam^, Array.unsafe_get(arr, i));
};
mutableParam^;
};
```
HashMapContainerType.re
```re
type t('key, 'value) = Js.Dict.t('value);
type t2('value) = t(string, 'value);
```
HashMapContainer.re
```re
let createEmpty = (): HashMapContainerType.t2('a) => Js.Dict.empty();
let get = (key: string, map: HashMapContainerType.t2('a)) =>
Js.Dict.get(map, key);
let entries = (map: HashMapContainerType.t2('a)): array((Js.Dict.key, 'a)) =>
map |> Js.Dict.entries;
let _mutableSet = (key: string, value, map) => {
Js.Dict.set(map, key, value);
map;
};
let _createEmpty = (): Js.Dict.t('a) => Js.Dict.empty();
let copy = (map: HashMapContainerType.t2('a)): HashMapContainerType.t2('a) =>
map
|> entries
|> ArrayContainerDoService.reduceOneParam(
(. newMap, (key, value)) => newMap |> _mutableSet(key, value),
_createEmpty(),
);
```
ImmutableHashMapContainerVO.re
```re
type t('key, 'value) = HashMapContainerType.t('key, 'value);
let createEmpty = HashMapContainer.createEmpty;
let set =
(key: string, value: 'a, map: HashMapContainerType.t2('a))
: HashMapContainerType.t2('a) => {
let newMap = map |> HashMapContainer.copy;
Js.Dict.set(newMap, key, value);
newMap;
};
let get = HashMapContainer.get;
```
MutableHashMap.re
```re
type t('key, 'value) = HashMapContainerType.t('key, 'value);
let createEmpty = HashMapContainer.createEmpty;
let set = (key: string, value: 'a, map: HashMapContainerType.t2('a)) => {
Js.Dict.set(map, key, value);
map;
};
let get = HashMapContainer.get;
```
现在我们可以通过修改ShaderManagerShaderEntity.re来修改ShaderManager的DO，加入programMap字段
ShaderManagerShaderEntity.re相关代码为：
```re
type t = {
...
programMap:
ImmutableHashMapContainerVO.t2(ShaderShaderEntity.t, ProgramShaderVO.t),
};
```
5、创建领域服务BuildInitShaderData，实现构造值对象InitShader
1)在srchttps://img.qb5200.com/download-x/domain_layerhttps://img.qb5200.com/download-x/domain/init/init_shader/service/中加入BuildInitShaderDataInitShaderDoService.re，创建领域服务BuildInitShaderData
BuildInitShaderDataInitShaderDoService.re代码为：
```re
let build = () => {
ShaderManagerShaderEntity.getAllGLSL()
|> List.map(((shaderName, glsl)) => {
(
{
shaderId: ShaderShaderEntity.getId(shaderName),
vs: GLSLShaderVO.getVS(glsl),
fs: GLSLShaderVO.getFS(glsl),
}: InitShaderInitShaderVO.singleInitShader
)
});
};
```
2)修改GLSLShaderVO.re，实现getVS、getFS函数
GLSLShaderVO.re相关代码为：
```re
let getVS = glsl =>
switch (glsl) {
| GLSL(vs, fs) => vs
};
let getFS = glsl =>
switch (glsl) {
| GLSL(vs, fs) => fs
};
```
3)修改ShaderManagerShaderEntity.re，加入getAllGLSL函数
ShaderManagerShaderEntity.re相关代码为：
```re
let getAllGLSL = () => {
ShaderManagerRepo.getAllGLSL();
};
```
4)修改ShaderManagerRepo.re，加入getAllGLSL函数
ShaderManagerShaderEntity.re相关代码为：
```re
let getAllGLSL = () => {
Repo.getShaderManager().glsls
|> List.map(((shaderId, (vs, fs))) => {
(ShaderShaderEntity.create(shaderId), GLSLShaderVO.create((vs, fs)))
});
};
```
6、在srchttps://img.qb5200.com/download-x/domain_layerhttps://img.qb5200.com/download-x/domain/init/init_shader/service/中加入InitShaderInitShaderDoService.re，创建领域服务InitShader
InitShaderInitShaderDoService.re代码为：
```re
let init = (): ResultContainerVO.t(unit, Js.Exn.t) => {
ContextContextEntity.getGl()
|> ResultContainerVO.bind(gl => {
//从着色器DO数据中构建值对象InitShader
BuildInitShaderDataInitShaderDoService.build()
|> ResultContainerVO.tryCatch(initShaderData => {
initShaderData
|> List.iter(
(
{shaderId, vs, fs}: InitShaderInitShaderVO.singleInitShader,
) => {
let program = ContextContextEntity.createProgram(gl);
/* 注意：领域服务不应该直接依赖Repo
应该通过实体ContextContextEntity而不是ShaderManagerRepo来将program设置到ShaderManager PO的programMap中！
*/
ContextContextEntity.setProgram(shaderId, program);
ContextContextEntity.initShader(vs, fs, program, gl)
|> ignore;
//用于运行测试
Js.log((shaderId, vs, fs));
})
})
});
};
```
7、修改ContextContextEntity.re，实现相关函数
ContextContextEntity.re相关代码为：
```re
let getGl = () => {
ContextRepo.getGl();
};
...
let createProgram = gl => gl |> WebGL1.createProgram;
let setProgram = (shaderId, program) => {
ShaderManagerRepo.setProgram(shaderId, program);
};
let _compileShader = (gl, glslSource, shader) => {
WebGL1.shaderSource(shader, glslSource, gl);
WebGL1.compileShader(shader, gl);
WebGL1.getShaderParameter(shader, WebGL1.getCompileStatus(gl), gl)
=== false
? {
let message = WebGL1.getShaderInfoLog(shader, gl);
//这里为了实现“从0开发3D引擎（十）：使用领域驱动设计，从最小3D程序中提炼引擎（第一部分）”提出的“处理错误优化”，用“抛出异常”而不是Result来处理错误
Error.error(
{j|shader info log: $message
glsl source: $glslSource
|j},
);
}
: shader;
};
let _linkProgram = (program, gl) => {
WebGL1.linkProgram(program, gl);
WebGL1.getProgramParameter(program, WebGL1.getLinkStatus(gl), gl) === false
? {
let message = WebGL1.getProgramInfoLog(program, gl);
//这里为了实现“从0开发3D引擎（十）：使用领域驱动设计，从最小3D程序中提炼引擎（第一部分）”提出的“处理错误优化”，用“抛出异常”而不是Result来处理错误
Error.error({j|link program error: $message|j});
}
: program;
};
let initShader = (vsSource: string, fsSource: string, program, gl) => {
let vs =
_compileShader(
gl,
vsSource,
WebGL1.createShader(WebGL1.getVertexShader(gl), gl),
);
let fs =
_compileShader(
gl,
fsSource,
WebGL1.createShader(WebGL1.getFragmentShader(gl), gl),
);
WebGL1.attachShader(program, vs, gl);
WebGL1.attachShader(program, fs, gl);
WebGL1.bindAttribLocation(program, 0, "a_position", gl);
_linkProgram(program, gl);
WebGL1.deleteShader(vs, gl);
WebGL1.deleteShader(fs, gl);
program;
};
```
8、修改ShaderManagerPOType.re，ShaderManager PO加入programMap字段
虽然programMap也是hash map，但不能直接使用领域层的值对象ImmutableHashMapContainerVO来定义它的类型！因为PO属于基础设施层，它不能依赖领域层！
因此，我们应该在基础设施层的“数据”中创建一个ImmutableHashMap.re模块，尽管它的类型和函数都与ImmutableHashMapContainerVO一样。
在src/infrastructure_layerhttps://img.qb5200.com/download-x/data/中创建文件夹structure/，在该文件夹中加入ImmutableHashMap.re。
为了方便，目前暂时直接用ImmutableHashMapContainerVO来实现ImmutableHashMap。
ImmutableHashMap.re代码为：
```re
type t2('key, 'a) = ImmutableHashMapContainerVO.t2('key, 'a);
let createEmpty = ImmutableHashMapContainerVO.createEmpty;
let set = ImmutableHashMapContainerVO.set;
```
修改ShaderManagerPOType.re，ShaderManager PO加入programMap字段：
```re
type shaderManager = {
...
programMap: ImmutableHashMap.t2(shaderId, WebGL1.program),
};
```
9、修改ShaderManagerRepo.re，实现setProgram函数
ShaderManagerRepo.re相关代码为：
```re
let _getProgramMap = ({programMap}) => programMap;
let setProgram = (shaderId, program) => {
Repo.setShaderManager({
...Repo.getShaderManager(),
programMap:
_getProgramMap(Repo.getShaderManager())
//这里也使用基础设施层的“数据”的ImmutableHashMap，因为操作的是ShaderManager PO的programMap
|> ImmutableHashMap.set(shaderId, program),
});
};
```
10、修改CreateRepo.re，实现创建ShaderManager PO的programMap字段
CreateRepo.re相关代码为：
```re
let create = () => {
...
shaderManager: {
...
programMap: ImmutableHashMap.createEmpty(),
},
};
```
### 实现用户代码并运行测试
1、在项目根目录上执行webpack命令，更新wd.js文件
```js
yarn webpack
```
2、实现index.html相关代码
index.html代码为：
```html
```
3、运行测试
运行index.html页面
打开控制台，可以看到打印了两次数组，每次数组内容为[Shader名称, vs, fs]，其中第一次的Shader名称为“shader2”，第二次为“shader1”
