How to use unity CreateExternalTexture on Android?-优快云博客

本文介绍如何在Unity和Java之间实现纹理的正确加载与显示。作者分享了使用CreateExternalTexture方法从Android本地侧加载图片到Unity时遇到的问题及解决办法。关键在于确保Unity与Java侧的纹理格式一致，并采用GLUtils.texImage2D替代GLES20.glTexImage2D。

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http://stackoverflow.com/questions/33324753/how-to-use-unity-createexternaltexture-on-android

Can someone please help me figure out what is the problem with my code? I am trying to load an image from the native side and send the texture to Unity. I am using Unity Pro 5.0.2f1.

Unity Side:

void Start () {
AndroidJavaObject mImageLoader = new AndroidJavaObject("com.saeid.android.LoadTexture2D");
Texture2D texture2D = new Texture2D(1920, 1080, TextureFormat.ARGB32, false);

Int32 texPtr = mImageLoader.Call <Int32> ("loadImageReturnTexturePtr", "/storage/sdcard0/Images/test.jpg");
Debug.Log("texture pointer? " + texPtr);
Texture2D nativeTexture = Texture2D.CreateExternalTexture (1920, 1080, TextureFormat.ARGB32 , false, false, (IntPtr)texPtr);
texture2D.UpdateExternalTexture(nativeTexture.GetNativeTexturePtr());
gameObject.GetComponent<Renderer>().material.mainTexture = texture2D;
}

Java Side:

public int loadImageReturnTexturePtr(String imagePath) {
Log.d(LOGTAG, "loading image1: " + imagePath);

Bitmap bitmap = BitmapFactory.decodeFile(imagePath);
Log.d(LOGTAG, "Bitmap is: " + bitmap);

ByteBuffer buffer = ByteBuffer.allocate(bitmap.getByteCount());
bitmap.copyPixelsToBuffer(buffer);

int textures[] = new int[1];
GLES20.glGenTextures(1, textures, 0);
int textureId = textures[0];

GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);
GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_RGBA, 1920, 1080, 0, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, buffer);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S,
GLES20.GL_CLAMP_TO_EDGE);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T,
GLES20.GL_CLAMP_TO_EDGE);
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);
Log.d(LOGTAG, "texture id returned: " + textureId);

return textureId;
}

So, I figured it out... The code is actually correct. except the texture format in both side should be the same. In my case, I have TextureFormat.ARGB32 (in unity side) and GLES20.GL_RGBA (in Java side) which don't match. Also somehow GLES20.glTexImage2D(...) didn't work for me. I replaced it with GLUtils.texImage2D(GLES20.GL_TEXTURE_2D,0, bitmap,0); and finally I noticed the same code works on same Unity versions and doesn't work on some other. for example it is not working in 5.0.2f1 but it works in 5.0.3.