ArCore场景窗体:检测图像时播放.mp4视频

我用了 ChromaKey sample 作为起点。

首先,我更改了视频使用的自定义材质,添加了一个标志来禁用chromakey过滤。

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,我基于hittest中的锚点放置了视频节点,并在其上方放置了一个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;
    }