my shader learning journey

###註記 POSITION為vertex shader中頂點位於object space時的坐標位置。
SV_POSITION用於Pixel shader，
表示頂點經過坐標變換後來到clip space時的坐標位置。
SV為System value的簡寫。

SV_Position can be specified as an input to a vertex shader as well as an output.
Pixel shaders can only write to parameters with the SV_Depth and SV_Target system-value semantics.

#SimpleShader Prepare one material-SimpleShderMat one shader-SimpleShader one Sphere in scene. Shere has SimpleShaderMat.

Result
	red Sphere

#Simple shader 2 使用a2f struct將model數據由application傳到vertex shader中，
這次傳送的數據有POSITION、NORMAL、TEXCOORD0。
struct v2f defined output of vertex shader.
vertex shader的輸出一定要有SV_POSITION,
才能將vertex render在畫面上。

而我們在vert func中把normal vector由[-1, 1]映射到[0, 1]範圍中，
並把獲得的color 數值丟給fragment shader來渲染。
Because the normal components are in the –1 to 1 range,
we scale and bias them so that the output colors are in a displayable 0 to 1 range.

###自訂義struct struct StructName{ Type Name : System semantic; Type Name : System semantic; ... };

#False Color
使用false color來可視化模型上的數據，例如：normal、tangent、紋理及頂點顏色。

vertext data inputs are declared in a structure. vertext structures are defined in UnityCG.cginc
(you can find it in folder "\Editor\Data\CGIncludes")

在這裡input使用了UnityCG中的appdata_full
會發現他已經包含了所有模型資料

在有小數位數(Have decimal places)的圖中，會看到多出來的藍色區塊(o.color.b=0.5)
In Have decimal places picture, an additional blue tint has been applied to coordinates outside of the 0 to 1 range
完整教學可以參考Unity Documentation- Providing vertex data to vertex programs