OpenGLES添加水印
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
OES纹理上添加水印，需要开个fbo来绘制OES的纹理，然后另外用一个Render来绘制绑定OES的纹理和添加水印，也就是说:OES和2D不能混用，不然不会起作用。如果可以混用（我试了混用绘制不出来），可以留言告诉我一下，谢谢。 - 使用
VBO需要注意点的位置。
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原始发表：2018-08-24，如有侵权请联系 cloudcommunity@tencent.com 删除
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