OpenGLES添加水印

作者: 曾大稳丶 | 来源:发表于2018-08-24 14:12 被阅读0次

原理

多个纹理绘制在一个surface上

理解了添加水印的原理，不管是视频水印还是图片水印都是很简单的了，只是使用的纹理不一样而已。如果是绘制文字水印的话，则需要将文字生成图片，然后将图片使用纹理绘制即可。

那么怎样将多个纹理添加到同一个surface上？

简单示例代码：


import android.content.Context;
import android.graphics.Bitmap;
import android.opengl.GLES20;
import android.util.Log;

import com.zzw.live.R;
import com.zzw.live.egl.EglSurfaceView;
import com.zzw.live.util.ShaderUtil;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;

public class CameraRender implements EglSurfaceView.Render {
    //顶点坐标
    static float vertexData[] = {   // in counterclockwise order:
            -1f, -1f, 0.0f, // bottom left
            1f, -1f, 0.0f, // bottom right
            -1f, 1f, 0.0f, // top left
            1f, 1f, 0.0f,  // top right

            0f, 0f, 0f,//水印预留位置
            0f, 0f, 0f,
            0f, 0f, 0f,
            0f, 0f, 0f
    };

    //纹理坐标  对应顶点坐标  与之映射
    static float textureData[] = {   // in counterclockwise order:
            0f, 1f, 0.0f, // bottom left
            1f, 1f, 0.0f, // bottom right
            0f, 0f, 0.0f, // top left
            1f, 0f, 0.0f,  // top right
    };
    //每一次取点的时候取几个点
    static final int COORDS_PER_VERTEX = 3;

    final int vertexCount = vertexData.length / COORDS_PER_VERTEX;
    //每一次取的总的点 大小
    static final int vertexStride = COORDS_PER_VERTEX * 4; // 4 bytes per vertex

    //位置
    protected FloatBuffer vertexBuffer;
    //纹理
    protected FloatBuffer textureBuffer;
    private int program;
    private int avPosition;

    //纹理位置
    private int afPosition;
    //纹理  默认第0个位置 可以不获取
    private int texture;


    //vbo id
    private int vboId;

    private int fboTextureId;

    private Context context;

    private Bitmap bitmap;
    private int waterTextureId;

    public CameraRender(Context context) {
        this.context = context;
        initWater();

        vertexBuffer = ByteBuffer.allocateDirect(vertexData.length * 4)
                .order(ByteOrder.nativeOrder())
                .asFloatBuffer()
                .put(vertexData);
        vertexBuffer.position(0);

        textureBuffer = ByteBuffer.allocateDirect(textureData.length * 4)
                .order(ByteOrder.nativeOrder())
                .asFloatBuffer()
                .put(textureData);
        textureBuffer.position(0);
    }

    @Override
    public void onSurfaceCreated() {
         //启用透明
        GLES20.glEnable(GLES20.GL_BLEND);
        GLES20.glBlendFunc(GLES20.GL_SRC_ALPHA, GLES20.GL_ONE_MINUS_SRC_ALPHA);
        program = ShaderUtil.createProgram(ShaderUtil.readRawTxt(context, R.raw.vertex_shader_screen),
                ShaderUtil.readRawTxt(context, R.raw.fragment_shader_screen));

        if (program > 0) {
            //获取顶点坐标字段
            avPosition = GLES20.glGetAttribLocation(program, "av_Position");
            //获取纹理坐标字段
            afPosition = GLES20.glGetAttribLocation(program, "af_Position");
            //获取纹理字段
            texture = GLES20.glGetUniformLocation(program, "sTexture");

            //创建vbo
            createVBO();

            //创建水印纹理
            createWaterTextureId();
        }
    }

    @Override
    public void onSurfaceChanged(int width, int height) {
        //宽高
        GLES20.glViewport(0, 0, width, height);
    }

    @Override
    public void onDrawFrame() {
        //清空颜色
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
        //设置背景颜色
        GLES20.glClearColor(1.0f, 1.0f, 1.0f, 1.0f);

        //使用程序
        GLES20.glUseProgram(program);

        //设置纹理
        //绑定渲染纹理  默认是第0个位置
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, fboTextureId);

        GLES20.glEnableVertexAttribArray(avPosition);
        GLES20.glEnableVertexAttribArray(afPosition);

        //使用VBO设置纹理和顶点值
        useVboSetVertext();

//        //设置顶点位置值
//        GLES20.glVertexAttribPointer(avPosition, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, vertexBuffer);
//        //设置纹理位置值
//        GLES20.glVertexAttribPointer(afPosition, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, textureBuffer);

        //绘制 GLES20.GL_TRIANGLE_STRIP:复用坐标
        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
        GLES20.glDisableVertexAttribArray(avPosition);
        GLES20.glDisableVertexAttribArray(afPosition);
        //解绑纹理
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);


        drawWater();
    }


    public void onDraw(int fboTextureId) {
        this.fboTextureId = fboTextureId;
        onDrawFrame();
    }

    /**
     * 创建vbo
     */
    private void createVBO() {
        //1. 创建VBO
        int[] vbos = new int[1];
        GLES20.glGenBuffers(vbos.length, vbos, 0);
        vboId = vbos[0];
        //2. 绑定VBO
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vboId);
        //3. 分配VBO需要的缓存大小
        GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER, vertexData.length * 4 + textureData.length * 4, null, GLES20.GL_STATIC_DRAW);
        //4. 为VBO设置顶点数据的值
        GLES20.glBufferSubData(GLES20.GL_ARRAY_BUFFER, 0, vertexData.length * 4, vertexBuffer);
        GLES20.glBufferSubData(GLES20.GL_ARRAY_BUFFER, vertexData.length * 4, textureData.length * 4, textureBuffer);
        //5. 解绑VBO
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
    }


    /**
     * 使用vbo设置顶点位置
     */
    private void useVboSetVertext() {
        //1. 绑定VBO
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vboId);
        //2. 设置顶点数据
        GLES20.glVertexAttribPointer(avPosition, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, 0);
        GLES20.glVertexAttribPointer(afPosition, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, vertexData.length * 4);
        //3. 解绑VBO
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
    }


    private void initWater() {
        bitmap = ShaderUtil.createTextImage("我是水印", 40, "#fff000", "#00000000", 0);

        //设置位置 根据需求自己配置
        float r = 1.0f * bitmap.getWidth() / bitmap.getHeight();
        float w = r * 0.1f;
        vertexData[12] = 0.8f - w;
        vertexData[13] = -0.8f;
        vertexData[14] = 0;

        vertexData[15] = 0.8f;
        vertexData[16] = -0.8f;
        vertexData[17] = 0;

        vertexData[18] = 0.8f - w;
        vertexData[19] = -0.7f;
        vertexData[20] = 0;

        vertexData[21] = 0.8f;
        vertexData[22] = -0.7f;
        vertexData[23] = 0;
    }

    private void createWaterTextureId() {

        int[] textureIds = new int[1];
        //创建纹理
        GLES20.glGenTextures(1, textureIds, 0);
        waterTextureId = textureIds[0];
        //绑定纹理
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, waterTextureId);
        //环绕（超出纹理坐标范围）  （s==x t==y GL_REPEAT 重复）
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_REPEAT);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_REPEAT);
        //过滤（纹理像素映射到坐标点）  （缩小、放大：GL_LINEAR线性）
        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);

        ByteBuffer bitmapBuffer = ByteBuffer.allocate(bitmap.getHeight() * bitmap.getWidth() * 4);//RGBA
        bitmap.copyPixelsToBuffer(bitmapBuffer);
        //将bitmapBuffer位置移动到初始位置
        bitmapBuffer.flip();

        //设置内存大小绑定内存地址
        GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_RGBA, bitmap.getWidth(), bitmap.getHeight(),
                0, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, bitmapBuffer);

        //解绑纹理
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);
    }


    public void drawWater() {
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vboId);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, waterTextureId);

        GLES20.glEnableVertexAttribArray(avPosition);
        GLES20.glEnableVertexAttribArray(afPosition);

        GLES20.glVertexAttribPointer(avPosition, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride,
                vertexStride * 4);//四个坐标之后的是水印的坐标
        GLES20.glVertexAttribPointer(afPosition, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride,
                vertexData.length * 4);

        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);

        GLES20.glDisableVertexAttribArray(avPosition);
        GLES20.glDisableVertexAttribArray(afPosition);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
    }

}

ShaderUtil.java



import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.opengl.GLES20;
import android.util.Log;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.ByteBuffer;

public class ShaderUtil {
    private static final String TAG = "ShaderUtil";

    public static String readRawTxt(Context context, int rawId) {
        InputStream inputStream = context.getResources().openRawResource(rawId);
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
        StringBuffer sb = new StringBuffer();
        String line;
        try {
            while ((line = reader.readLine()) != null) {
                sb.append(line).append("\n");
            }
            reader.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return sb.toString();
    }

    public static int loadShader(int shaderType, String source) {
        // create a vertex shader type (GLES20.GL_VERTEX_SHADER)
        // or a fragment shader type (GLES20.GL_FRAGMENT_SHADER)
        int shader = GLES20.glCreateShader(shaderType);
        if (shader != 0) {
            //添加代码到shader
            GLES20.glShaderSource(shader, source);
            //编译shader
            GLES20.glCompileShader(shader);
            int[] compile = new int[1];
            //检测是否编译成功
            GLES20.glGetShaderiv(shader, GLES20.GL_COMPILE_STATUS, compile, 0);
            if (compile[0] != GLES20.GL_TRUE) {
                Log.d(TAG, "shader compile error");
                GLES20.glDeleteShader(shader);
                shader = 0;
            }
        }
        return shader;
    }

    public static int createProgram(String vertexSource, String fragmentSource) {
        //获取vertex shader
        int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER, vertexSource);
        if (vertexShader == 0) {
            return 0;
        }
        //获取fragment shader
        int fragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentSource);
        if (fragmentShader == 0) {
            return 0;
        }
        //创建一个空的渲染程序
        int program = GLES20.glCreateProgram();
        if (program != 0) {
            //添加vertexShader到渲染程序
            GLES20.glAttachShader(program, vertexShader);
            //添加fragmentShader到渲染程序
            GLES20.glAttachShader(program, fragmentShader);
            //关联为可执行渲染程序
            GLES20.glLinkProgram(program);
            int[] linsStatus = new int[1];
            //检测是否关联成功
            GLES20.glGetProgramiv(program, GLES20.GL_LINK_STATUS, linsStatus, 0);
            if (linsStatus[0] != GLES20.GL_TRUE) {
                Log.d(TAG, "link program error");
                GLES20.glDeleteProgram(program);
                program = 0;
            }
        }
        return program;
    }


    public static Bitmap createTextImage(String text, int textSize, String textColor, String bgColor, int padding) {

        Paint paint = new Paint();
        paint.setColor(Color.parseColor(textColor));
        paint.setTextSize(textSize);
        paint.setStyle(Paint.Style.FILL);
        paint.setAntiAlias(true);

        float width = paint.measureText(text, 0, text.length());

        float top = paint.getFontMetrics().top;
        float bottom = paint.getFontMetrics().bottom;

        Bitmap bm = Bitmap.createBitmap((int) (width + padding * 2), (int) ((bottom - top) + padding * 2), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bm);

        canvas.drawColor(Color.parseColor(bgColor));
        canvas.drawText(text, padding, -top + padding, paint);
        return bm;
    }

    public static int loadBitmapTexture(Bitmap bitmap) {
        int[] textureIds = new int[1];
        GLES20.glGenTextures(1, textureIds, 0);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureIds[0]);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_REPEAT);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_REPEAT);
        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);

        ByteBuffer bitmapBuffer = ByteBuffer.allocate(bitmap.getHeight() * bitmap.getWidth() * 4);//ARGB
        bitmap.copyPixelsToBuffer(bitmapBuffer);
        bitmapBuffer.flip();

        GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_RGBA, bitmap.getWidth(),
                bitmap.getHeight(), 0, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, bitmapBuffer);
        return textureIds[0];
    }


}

我们只需要在当前GL_TEXTURE_2D纹理绘制之后在glBindTexture绑定水印的纹理绘制即可。这里需要注意的几个点:

需要开启透明,不然没有透明效果。

//启用透明
GLES20.glEnable(GLES20.GL_BLEND);
GLES20.glBlendFunc(GLES20.GL_SRC_ALPHA, GLES20.GL_ONE_MINUS_SRC_ALPHA);

如果是使用fbo来离屏渲染OES纹理添加水印，需要在开个fbo来使用2D绘制OES的纹理和添加水印，然后另外用一个Render来绘制fbo纹理，也就是说:fbo里面OES和2D不能混用，不然不会起作用。这里如果说错，可以留言指导一下。
使用VBO需要注意点的位置。

OpenGLES添加水印

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