android - ArCore Sceneform：检测图像时播放 .mp4 视频

Question

当我找到一张图片时，我想在它上面放置一个文本和一个视频。文本视图放置在场景中，但视频没有，它只是添加到我的主布局中间。我正在使用组件 VideoView，我不确定这是问题所在

override fun onCreate(savedInstanceState: Bundle?) {
         (....)
        arFragment!!.arSceneView.scene.addOnUpdateListener { this.onUpdateFrame(it) }
        arSceneView = arFragment!!.arSceneView

}

private fun onUpdateFrame(frameTime: FrameTime) {
    val frame = arFragment!!.arSceneView.arFrame

    val augmentedImages = frame.getUpdatedTrackables(AugmentedImage::class.java)

    for (augmentedImage in augmentedImages) {
        if (augmentedImage.trackingState == TrackingState.TRACKING) {

            if (augmentedImage.name.contains("car") && !modelCarAdded) {
                renderView(arFragment!!,
                        augmentedImage.createAnchor(augmentedImage.centerPose))
                modelCarAdded = true
            }
        }
    }

}

text_info 只是一个 TextView 组件，video_youtube 是一个带有 VideoView 的 RelativeLayout。

   private fun renderView(fragment: ArFragment, anchor: Anchor) {
    //WORKING
    ViewRenderable.builder()
            .setView(this, R.layout.text_info)
            .build()
            .thenAccept { renderable ->
                (renderable.view as TextView).text = "Example"
                addNodeToScene(fragment, anchor, renderable, Vector3(0f, 0.2f, 0f))

            }
            .exceptionally { throwable ->
                val builder = AlertDialog.Builder(this)
                builder.setMessage(throwable.message)
                        .setTitle("Error!")
                val dialog = builder.create()
                dialog.show()
                null
            }
    //NOT WORKING
    ViewRenderable.builder()
            .setView(this, R.layout.video_youtube)
            .build()
            .thenAccept { renderable ->
                val view = renderable.view
                videoRenderable = renderable
                val path = "android.resource://" + packageName + "/" + R.raw.googlepixel
                view.video_player.setVideoURI(Uri.parse(path))
                renderable.material.setExternalTexture("videoTexture", texture)
                val videoNode = addNodeToScene(fragment, anchor, renderable, Vector3(0.2f, 0.5f, 0f))
                if (!view.video_player.isPlaying) {
                    view.video_player.start()
                    texture
                            .surfaceTexture
                            .setOnFrameAvailableListener {
                                videoNode.renderable = videoRenderable
                                texture.surfaceTexture.setOnFrameAvailableListener(null)
                            }
                } else {
                    videoNode.renderable = videoRenderable
                }

            }
            .exceptionally { throwable ->
                null
            }
}

private fun addNodeToScene(fragment: ArFragment, anchor: Anchor, renderable: Renderable, vector3: Vector3): Node {
        val anchorNode = AnchorNode(anchor)
        val node = TransformableNode(fragment.transformationSystem)
        node.renderable = renderable
        node.setParent(anchorNode)
        node.localPosition = vector3
        fragment.arSceneView.scene.addChild(anchorNode)
        return node
    }

我尝试使用色度键视频示例，但我不希望视频的白色部分是透明的。而且我不确定我是否需要模型 (.sfb) 来显示视频。

Answer 1

我使用ChromaKey 示例作为起点。

首先，我通过添加一个标志来禁用色键过滤来更改用于视频的自定义材料。

material {
    "name" : "Chroma Key Video Material",
    "defines" : [
        "baseColor"
    ],
    "parameters" : [
        {
           // The texture displaying the frames of the video.
           "type" : "samplerExternal",
           "name" : "videoTexture"
        },
        {
            // The color to filter out of the video.
            "type" : "float4",
            "name" : "keyColor"
        },
        {
            "type" : "bool",
            "name" : "disableChromaKey",
        }
    ],
    "requires" : [
        "position",
        "uv0"
    ],
    "shadingModel" : "unlit",
    // Blending is "masked" instead of "transparent" so that the shadows account for the
    // transparent regions of the video instead of just the shape of the mesh.
    "blending" : "masked",
    // Material is double sided so that the video is visible when walking behind it.
    "doubleSided" : true
}

fragment {
    vec3 desaturate(vec3 color, float amount) {
        // Convert color to grayscale using Luma formula:
        // https://en.wikipedia.org/wiki/Luma_%28video%29
        vec3 gray = vec3(dot(vec3(0.2126, 0.7152, 0.0722), color));

        return vec3(mix(color, gray, amount));
    }

    void material(inout MaterialInputs material) {
        prepareMaterial(material);

        vec2 uv = getUV0();

        if (!gl_FrontFacing) {
          uv.x = 1.0 - uv.x;
        }

        vec4 color = texture(materialParams_videoTexture, uv).rgba;

        if (!materialParams.disableChromaKey) {
            vec3 keyColor = materialParams.keyColor.rgb;

            float threshold = 0.675;
            float slope = 0.2;

            float distance = abs(length(abs(keyColor - color.rgb)));
            float edge0 = threshold * (1.0 - slope);
            float alpha = smoothstep(edge0, threshold, distance);
            color.rgb = desaturate(color.rgb, 1.0 - (alpha * alpha * alpha));

            material.baseColor.a = alpha;
            material.baseColor.rgb = inverseTonemapSRGB(color.rgb);
            material.baseColor.rgb *= material.baseColor.a;
        } else {
            material.baseColor = color;
        }
    }
}

然后在 .sfa 文件中将 `disableChromaKey' 设置为 false：

 materials: [
    {
      name: 'DefaultMaterial',
      parameters: [
        {
          videoTexture: {
            external_path: 'MISSING_PATH',
          },
        },
        {
          keyColor: [
            0,
            0,
            0,
            0,
          ],
        },
        {
            disableChromaKey : true,
        }
      ],
      source: 'sampledata/models/chroma_key_video_material.mat',
    },
  ],

然后我根据来自 hittest 的锚放置视频节点，并在其上方放置一个 ViewRenderable 节点用于文本。

   private Node createVideoDisplay(final AnchorNode parent, Vector3 localPosition, String title) {
        // Create a node to render the video and add it to the anchor.
        Node videoNode = new Node();
        videoNode.setParent(parent);
        videoNode.setLocalPosition(localPosition);

        // Set the scale of the node so that the aspect ratio of the video is correct.
        float videoWidth = mediaPlayer.getVideoWidth();
        float videoHeight = mediaPlayer.getVideoHeight();
        videoNode.setLocalScale(
                new Vector3(
                        VIDEO_HEIGHT_METERS * (videoWidth / videoHeight),
                        VIDEO_HEIGHT_METERS, 1.0f));

        // Place the text above the video
        final float videoNodeHeight = VIDEO_HEIGHT_METERS+ localPosition.y;
        ViewRenderable.builder().setView(this,R.layout.video_title)
                .build().thenAccept(viewRenderable -> {
                   Node titleNode =  new Node();
                   titleNode.setLocalPosition(new Vector3(0,videoNodeHeight,0));
                   titleNode.setParent(parent);
                   titleNode.setRenderable(viewRenderable);
            ((TextView)viewRenderable.getView().findViewById(R.id.video_text))
                           .setText(title);
        });

        return videoNode;
    }