Engine development plan ：

shader Compiling system （cache）

hlsl -> glsl
Reference resources ：
https://zhuanlan.zhihu.com/p/462659745
https://zhuanlan.zhihu.com/p/56510874

Then learn from the unreal engine source code ：

You can use ShaderConductor, It can be relied on ：SPIRV-Cross、DirectXShaderCompiler（DXC）、cxxopts etc. .

Current plan ： I hope I can only write one in the future hlsl, Each compilation is compiled and applicable to all graphics api The circumstances of , Deposit in cache in .

About shader reflections , about spir-v, Yes SPIRV-Reflect：

dx I don't know effect Or something dx12 The official shader reflection .

Code reflection system （ You can refer to games104 and The realization of Unreal Engine ）.

101. Content Browser/Asset Panel

We obviously want to use the standard library filesystem

here stem and filename The difference is whether there is a file suffix , such as ：

102. Content Browser Panel - ImGui Drag Drop

We have to be the only one here id identification , Otherwise, you should use ImageButtonEx And so on. .

Content Browser Panel - ImGui Drag Drop

Otherwise, it will lead to the fact that dragging into the scene is always one bug.

Another thing to note is that here ：

ImGui::SetDragDropPayload("CONTENT_BROWSER_ITEM", itemPath, (wcslen(itemPath) + 1) * sizeof(wchar_t), ImGuiCond_Once);

We write the size of the pathname ：(wcslen(itemPath) + 1) * sizeof(wchar_t), Add 1 Because null terminal Something （ It's actually that \0 ？）

103. Textures for Entities!

105. PLAY BUTTON!

106. 2D PHYSICS!

Generally, our update order is script -> physics -> render

It can be seen in Scene::OnUpdateRuntime

107. Universally Unique Identifiers (UUID/GUID)

here uuid We always make a value at random , Not simply ++, such as 0123456 representative 7 individual entity, The reason is that, for example, there are multiple people to build a game , Then it's possible for both people to create one entity And the labels become 5 + 1 = 6 Such a situation .

Of course, you can also make one server Every time from server Where to get a specific id

We can simply use an example unordered_set To detect conflicts .

Want to make unordered_map Can use our UUID As key, Write the following template specialization ：

namespace std
{
    
	template<>
	struct hash<HEngine::UUID>
	{
    
		std::size_t operator()(const HEngine::UUID& uuid) const
		{
    
			return hash<uint64_t>()((uint64_t)uuid);
		}
	};
}

Some people suggest using a unordeed_set Or something , as follows ：

however cherno This is not recommended , Two reasons ：

1. The risk of conflict is actually very low , And doing so reduces performance
2. This is a local Of , It means that if you change a computer, it will be completely useless for others to do this project .

108. Playing and Stopping Scenes (and Resetting)

109. Rendering Circles in a Game Engine

110. Rendering Lines in a Game Engine

111. Circle Physics Colliders

Here I find there is something wrong , That is, the radius equivalence of the physical system is in Scene.cpp Of OnRuntimeStart Preset in function , But rely on those component The initial value of the , Like here CircleCollider2DComponent, If the radius is not equal to the radius of the actual rendered object, there is a problem . So I think we should actually assign values to each frame .

112. Visualizing Physics Colliders