渲染02-内置Uniform

参考:
CesiumJS 源码杂谈 - 从光到 Uniform

渲染02-内置Uniform

1 Unifrom 的接口

路径: pacaages/engin/Source/Renderer/AutomaticUniforms.js

AutomaticUniforms 实际上是 Cesium 暴露给着色使用的接口集合。

AutomaticUniforms┖ AutomaticUniform(czm_projection/czm_viewport/czm_viewportOrthographic...)

// AutomaticUniform包含:
czm_projection
czm_viewport
czm_viewportOrthographic
...

AutomaticUniforms = {czm_projection: new AutomaticUniform({size: 1,datatype: WebGLConstants.FLOAT_MAT4,getValue: function (uniformState) {return uniformState.projection;},})
}

2 Unifrom 的更新

内置unifrom实际上是 UniformState 负责更新。

路径: pacaages/engin/Source/Renderer/UniformState.js

类的从属关系:

Scene┣ FrameState(_frameState)┖ context┖ Context(_context)┖ UniformState(_us)

UniformState 更新的函数调用关系:

// Scene.js
fn render()UniformState.update();this.updateCamera();

3 Unifrom 的使用

同 DrawCommand 的执行。

简化版调用过程:

// Scene.js
fn render()// 1) 更新Uniform值UniformState.update();// 更新相机相关参数UniformState.updateCamera(camera);// 2) 执行命令DrawCommand.execute()// 使用 UniformContex.draw();

UniformState 关键成员:

czm_xxx 文档