ネイティブプラグインが作成したテクスチャをUnityで使用するサンプル

LoadTexture.cs

using UnityEngine;
using System;
using System.Runtime.InteropServices;

public class LoadTexture : MonoBehaviour {

	[DllImport ("__Internal")]
	private static extern IntPtr CreateTexture(string filename, out int w, out int h);

	Texture2D tex = null;

	void Start()
	{
		tex = new Texture2D(128,128, TextureFormat.ARGB32, false);
		renderer.material.mainTexture = tex;
	}

	void OnGUI()
	{
		// アップデートする場合
		if( GUILayout.Button("Push", GUILayout.Width(300), GUILayout.Height(100)))
		{
			int width, height;
			IntPtr ptr = CreateTexture(Application.streamingAssetsPath +  "/icon.png", out width, out height);
			tex.UpdateExternalTexture(ptr);
		}
		
		// 新規にテクスチャ作る場合
		if( GUILayout.Button("Push", GUILayout.Width(300), GUILayout.Height(100)))
		{
			int width, height;
			IntPtr ptr = CreateTexture(Application.streamingAssetsPath +  "/icon2.png", out width, out height);

			Texture2D nativeTexture = Texture2D.CreateExternalTexture( width, height, TextureFormat.ARGB32, false,false,ptr);
			tex.UpdateExternalTexture(nativeTexture.GetNativeTexturePtr());
		}

	}
}

NativePlugins.mm

//
//  NativePlugins.mm
//  Unity-iPhone
//
//  Created by tsubaki_t1 on 2014/01/18.
//
extern "C"
{
    void* CreateTexture(const char* fileName, int * w, int* h)
    {
        NSString* imageName = [NSString stringWithUTF8String:fileName];
        UIImage* teximage = [[UIImage imageWithContentsOfFile: imageName] retain];
        
        CGImageRef textureImage = teximage.CGImage;

        unsigned texWidth = CGImageGetWidth(textureImage);
        unsigned texHeight = CGImageGetHeight(textureImage);
        *w = (int)texWidth;
        *h = (int)texHeight;
        
        GLubyte *textureData = (GLubyte *)malloc(texWidth * texHeight * 4);
        CGContextRef textureContext = CGBitmapContextCreate(textureData, texWidth, texHeight, 8, texWidth * 4,
                                        CGImageGetColorSpace(textureImage), kCGImageAlphaPremultipliedLast);
        CGContextDrawImage(textureContext, CGRectMake(0.0, 0.0, (float)texWidth, (float)texHeight), textureImage);
        CGContextRelease(textureContext);
        
        GLuint texid;
        
        glGenTextures(1, &texid);
        glBindTexture(GL_TEXTURE_2D, texid);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texWidth, texHeight, 0, GL_RGBA,GL_UNSIGNED_BYTE, textureData);
        glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); 
        glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); 
        
        [textureImage release];
        free(textureData);
        
        return (void*)(intptr_t)texid;
    }
}