java - 如何使用 GPUImage 库 "subtract"滤色器？

Question

目前，BlendModes(减去、排除等)使用 LauncherImage 作为 mask 。我可以将这些 BlendMode 应用于 ColorMatrix 吗？

我正在使用 GPUImageLibrary :

colorMatrix[
    0.393, 0.7689999, 0.18899999, 0, 0,
    0.349, 0.6859999, 0.16799999, 0, 0,
    0.272, 0.5339999, 0.13099999, 0, 0,
    0,     0,         0,          1, 0];

SubtractBlendFilter.java

public class GPUImageSubtractBlendFilter extends GPUImageTwoInputFilter {
    public static final String SUBTRACT_BLEND_FRAGMENT_SHADER = "varying highp vec2 textureCoordinate;\n" +
            " varying highp vec2 textureCoordinate2;\n" +
            "\n" +
            " uniform sampler2D inputImageTexture;\n" +
            " uniform sampler2D inputImageTexture2;\n" +
            " \n" +
            " void main()\n" +
            " {\n" +
            "   lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);\n" +
            "   lowp vec4 textureColor2 = texture2D(inputImageTexture2, textureCoordinate2);\n" +
            "\n" +
            "   gl_FragColor = vec4(textureColor.rgb - textureColor2.rgb, textureColor.a);\n" +
            " }";

    public GPUImageSubtractBlendFilter() {
        super(SUBTRACT_BLEND_FRAGMENT_SHADER);
    }
}

GPUIMageTwoInputFilter.java

public class GPUImageTwoInputFilter extends GPUImageFilter {
    private static final String VERTEX_SHADER = "attribute vec4 position;\n" +
            "attribute vec4 inputTextureCoordinate;\n" +
            "attribute vec4 inputTextureCoordinate2;\n" +
            " \n" +
            "varying vec2 textureCoordinate;\n" +
            "varying vec2 textureCoordinate2;\n" +
            " \n" +
            "void main()\n" +
            "{\n" +
            "    gl_Position = position;\n" +
            "    textureCoordinate = inputTextureCoordinate.xy;\n" +
            "    textureCoordinate2 = inputTextureCoordinate2.xy;\n" +
            "}";

    public int mFilterSecondTextureCoordinateAttribute;
    public int mFilterInputTextureUniform2;
    public int mFilterSourceTexture2 = OpenGlUtils.NO_TEXTURE;
    private ByteBuffer mTexture2CoordinatesBuffer;
    private Bitmap mBitmap;

    public GPUImageTwoInputFilter(String fragmentShader) {
        this(VERTEX_SHADER, fragmentShader);
    }

    public GPUImageTwoInputFilter(String vertexShader, String fragmentShader) {
        super(vertexShader, fragmentShader);
        setRotation(Rotation.NORMAL, false, false);
    }

    @Override
    public void onInit() {
        super.onInit();

        mFilterSecondTextureCoordinateAttribute = GLES20.glGetAttribLocation(getProgram(), "inputTextureCoordinate2");
        mFilterInputTextureUniform2 = GLES20.glGetUniformLocation(getProgram(), "inputImageTexture2"); // This does assume a name of "inputImageTexture2" for second input texture in the fragment shader
        GLES20.glEnableVertexAttribArray(mFilterSecondTextureCoordinateAttribute);

        if (mBitmap != null&&!mBitmap.isRecycled()) {
            setBitmap(mBitmap);
        }
    }

    public void setBitmap(final Bitmap bitmap) {
        if (bitmap != null && bitmap.isRecycled()) {
            return;
        }
        mBitmap = bitmap;
        if (mBitmap == null) {
            return;
        }
        runOnDraw(new Runnable() {
            public void run() {
                if (mFilterSourceTexture2 == OpenGlUtils.NO_TEXTURE) {
                    if (bitmap == null || bitmap.isRecycled()) {
                        return;
                    }
                    GLES20.glActiveTexture(GLES20.GL_TEXTURE3);
                    mFilterSourceTexture2 = OpenGlUtils.loadTexture(bitmap, OpenGlUtils.NO_TEXTURE, false);
                }
            }
        });
    }

    public Bitmap getBitmap() {
        return mBitmap;
    }

    public void recycleBitmap() {
        if (mBitmap != null && !mBitmap.isRecycled()) {
            mBitmap.recycle();
            mBitmap = null;
        }
    }

    public void onDestroy() {
        super.onDestroy();
        GLES20.glDeleteTextures(1, new int[]{
                mFilterSourceTexture2
        }, 0);
        mFilterSourceTexture2 = OpenGlUtils.NO_TEXTURE;
    }

    @Override
    protected void onDrawArraysPre() {
        GLES20.glEnableVertexAttribArray(mFilterSecondTextureCoordinateAttribute);
        GLES20.glActiveTexture(GLES20.GL_TEXTURE3);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, mFilterSourceTexture2);
        GLES20.glUniform1i(mFilterInputTextureUniform2, 3);

        mTexture2CoordinatesBuffer.position(0);
        GLES20.glVertexAttribPointer(mFilterSecondTextureCoordinateAttribute, 2, GLES20.GL_FLOAT, false, 0, mTexture2CoordinatesBuffer);
    }

    public void setRotation(final Rotation rotation, final boolean flipHorizontal, final boolean flipVertical) {
        float[] buffer = TextureRotationUtil.getRotation(rotation, flipHorizontal, flipVertical);

        ByteBuffer bBuffer = ByteBuffer.allocateDirect(32).order(ByteOrder.nativeOrder());
        FloatBuffer fBuffer = bBuffer.asFloatBuffer();
        fBuffer.put(buffer);
        fBuffer.flip();

        mTexture2CoordinatesBuffer = bBuffer;
    }
}

我猜这涉及使用 String SUBTRACT_BLEND_GRAGMENT_SHADER 和 String VERTEX_SHADER 进行更改。

Answer 1

颜色矩阵是将某些像素的新颜色分量值定义为同一像素当前颜色分量的线性函数的实体。 IE。颜色矩阵转换的唯一输入是像素，应该转换哪些颜色。没有办法让其他像素参与这种转换。无论它们是来自另一个图像的像素，还是转换后像素的邻居，都是不可能的。