EncodeToWebP flips the texture

[zerg4000]

After EncodeToWebP result image wrong

`var textasset = Resources.Load ("webp");
var bytes = textasset.bytes;

Error lError;
Texture2D texture = Texture2DExt.CreateTexture2DFromWebP(bytes, lMipmaps: true, lLinear: true, lError: out lError);

if (lError == Error.Success) {
image2.texture = texture;
} else {
Debug.LogError("Webp Load Error : " + lError.ToString());
}

RenderTexture tmp = RenderTexture.GetTemporary(
texture.width,
texture.height,
0,
RenderTextureFormat.Default,
RenderTextureReadWrite.Linear);

// Blit the pixels on texture to the RenderTexture
Graphics.Blit(texture, tmp);
// Backup the currently set RenderTexture
RenderTexture previous = RenderTexture.active;
// Set the current RenderTexture to the temporary one we created
RenderTexture.active = tmp;

// Create a new readable Texture2D to copy the pixels to it
Texture2D myTexture2D = new Texture2D(texture.width, texture.height);

// Copy the pixels from the RenderTexture to the new Texture
myTexture2D.ReadPixels(new Rect(0, 0, tmp.width, tmp.height), 0, 0);
myTexture2D.Apply();

// Reset the active RenderTexture
RenderTexture.active = previous;

// Release the temporary RenderTexture
RenderTexture.ReleaseTemporary(tmp);

// "myTexture2D" now has the same pixels from "texture" and it's readable.

string fExport = Application.dataPath + "/test.webp";
byte[] bExport = myTexture2D.EncodeToWebP(25, out lError);
File.WriteAllBytes(fExport, bExport);`

[netpyoung]

That is problem to using webp on unity.
Unity's texture need to flip updown.

To archive that flip like that

unity.webp/unity_project/Assets/example4/EncodeToWebP.cs

Line 61 in 76a58b0

{// Flip updown.

or using advanced config with WebPEncode API

https://developers.google.com/speed/webp/docs/api

[netpyoung]

• added shader for flip case(just uv's v to one minus)

• https://github.com/netpyoung/unity.webp/blob/9219be2c51254e89837150e80e8d5643e0334a6d/unity_project/Assets/unity.webp/Resources/sg_UnlitFlipTexture.shadergraph