[OpenGL ES] FBO 帧缓冲对象

最新推荐文章于 2024-11-13 20:51:11 发布

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最新推荐文章于 2024-11-13 20:51:11 发布

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分类专栏： RTMP 文章标签： opengl android

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FBO： Frame Buffer object 帧缓冲对象

为什么要用FBO?
当需要对纹理进行多次渲染采样时，而这些渲染采样是不需要展示给用户看的，可以用一个单独的缓冲对象（离屏渲染）来存储这几次渲染采样的结果，等处理完后才显示到窗口上。

优势
提高渲染效率，避免闪屏，可以很方便的实现纹理共享等。

渲染方式
渲染到缓冲区（Render）- 深度测试和模板测试
渲染到纹理（Texture）- 图像渲染

创建FBO

1、创建FBO
GLES20.glGenBuffers(1, fbos, 0);

2、绑定FBO
GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, fbos[0]);

3、设置FBO分配内存大小
GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_RGBA, 720, 1280, 0, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, null);

4、把纹理绑定到FBO
GLES20.glFramebufferTexture2D(GLES20.GL_FRAMEBUFFER, GLES20.GL_COLOR_ATTACHMENT0, GLES20.GL_TEXTURE_2D, textureid, 0);

5、检查FBO绑定是否成功
GLES20.glCheckFramebufferStatus(GLES20.GL_FRAMEBUFFER) != GLES20.GL_FRAMEBUFFER_COMPLETE)

6、解绑FBO
GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);

使用FBO

1、绑定FBO
GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, fbos[0]);

2、获取需要绘制的图片纹理，然后绘制渲染

3、解绑FBO
GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);

4、再把绑定到FBO的纹理绘制渲染出来

GGLTextureRender

package com.example.opengldemo;

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

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

public class GGLTextureRender implements MyGLSurfaceView.MyGLRender {

    private Context context;
    //顶点坐标
    private final float[] vertexData = {
            -1f, -1f,
            1f, -1f,
            -1f, 1f,
            1f, 1f
    };

    //纹理坐标
    private final float[] fragmentData = {
            0f, 0f,
            1f, 0f,
            0f, 1f,
            1f, 1f
    };

    private FloatBuffer vertexBuffer;
    private FloatBuffer fragmentBuffer;

    public GGLTextureRender(Context context) {
        this.context = context;

        /***********************使用FBO-START************************************************/
        fboRender = new FboRender(context);
        /******************************FBO-END***********************************************/

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

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

    private int program;

    private int vPosition;
    private int fPosition;

    private int textureid;
    private int sampler;

    private int vboId;
    private int fboId;

    private int imgTextureId;

    private FboRender fboRender;

    @Override
    public void onSufaceCreated() {

        /***********************使用FBO-START************************************************/
        fboRender.onCreate();
        /******************************FBO-END***********************************************/

        String vertexSource = GShaderUtil.getRawResource(context, R.raw.vertex_shader);
        String fragmentSource = GShaderUtil.getRawResource(context, R.raw.fragment_shader);
        program = GShaderUtil.createProgram(vertexSource, fragmentSource);

        if (program > 0) {
            //顶点坐标
            vPosition = GLES20.glGetAttribLocation(program, "v_Position");
            //纹理坐标
            fPosition = GLES20.glGetAttribLocation(program, "f_Position");

            sampler = GLES20.glGetUniformLocation(program,"sTexture");

            int [] vbos = new int[1];
            GLES20.glGenBuffers(1, vbos, 0);
            vboId = vbos[0];
            //绑定
            GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vboId);
            //分配内存
            GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER, vertexData.length*4 + fragmentData.length*4,
                    null,GLES20. GL_STATIC_DRAW);
            //缓存到显存
            GLES20.glBufferSubData(GLES20.GL_ARRAY_BUFFER, 0, vertexData.length * 4, vertexBuffer);
            GLES20.glBufferSubData(GLES20.GL_ARRAY_BUFFER, vertexData.length * 4, fragmentData.length*4,
                    fragmentBuffer);
            //解绑
            GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);

           /***********************创建FBO-START************************************************/
            int [] fbos = new int[1];
            GLES20.glGenBuffers(1, fbos, 0);
            fboId = fbos[0];
            //绑定
            GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER,fboId);
            /******************************FBO-END***********************************************/

            //生成纹理
            int[] textureIds = new int[1];
            GLES20.glGenTextures(1, textureIds, 0);
            textureid = textureIds[0];

            GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureid);
            GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
            GLES20.glUniform1i(sampler, 0);

            //设置环绕过滤方法
            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);

            /***********************创建FBO-START************************************************/
            //设置FBO分配内存大小
            GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_RGBA, 900, 1600, 0,
                    GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, null);
            //把纹理绑定到FBO
            GLES20.glFramebufferTexture2D(GLES20.GL_FRAMEBUFFER, GLES20.GL_COLOR_ATTACHMENT0,
                    GLES20.GL_TEXTURE_2D, textureid, 0);
            //检查FBO绑定是否成功
            if(GLES20.glCheckFramebufferStatus(GLES20.GL_FRAMEBUFFER) != GLES20.GL_FRAMEBUFFER_COMPLETE){
                Log.e("godv", "fbo error");
            }else {
                Log.e("godv", "fbo success");
            }
            /******************************FBO-END***********************************************/

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

            /***********************创建FBO-START************************************************/
            //解绑
            GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);
            imgTextureId = loadTexture(R.drawable.androids);
            /******************************FBO-END***********************************************/
        }
    }

    @Override
    public void onSufaceChanged(int width, int height) {
        GLES20.glViewport(0,0,width,height);

        /***********************使用FBO-START************************************************/
        fboRender.onChange(width, height);
        /******************************FBO-END***********************************************/

    }

    @Override
    public void onDrawFrame() {

        /***********************使用FBO-START************************************************/
        //绑定FBO  离屏渲染
        GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, fboId);
        /******************************FBO-END***********************************************/

        //清屏
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
        //使用颜色清屏
        GLES20.glClearColor(1.0f, 0.0f, 0.0f, 1.0f);

        //使用program
        GLES20.glUseProgram(program);

        /***********************使用FBO-START************************************************/
        //绑定FBO纹理id
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, imgTextureId);
        /******************************FBO-END***********************************************/

        //绑定VBO
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vboId);

        //使用顶点坐标
        GLES20.glEnableVertexAttribArray(vPosition);
        //传0 从VBO中取值
        GLES20.glVertexAttribPointer(vPosition, 2, GLES20.GL_FLOAT, false, 8, 0);

        GLES20.glEnableVertexAttribArray(fPosition);

        //VBO
        GLES20.glVertexAttribPointer(fPosition, 2, GLES20.GL_FLOAT, false, 8,
                vertexData.length * 4);

        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
        //解绑
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);

        //解绑VBO
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);

        /***********************使用FBO-START************************************************/
        //解绑FBO
        GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);
        fboRender.onDraw(textureid);
        /******************************FBO-END***********************************************/

    }

    /***********************使用FBO-START************************************************/
    /*
    返回图片数据的纹理
     */
        private int loadTexture(int src){
            //创建纹理
            int[] textureIds = new int[1];
            GLES20.glGenTextures(1, textureIds, 0);
            //绑定纹理
            GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureIds[0]);
            //设置环绕过滤方法
            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);

            Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(),src);
            GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0);
            //解绑
            GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);
            return textureIds[0];
        }
    /******************************FBO-END***********************************************/

}

FboRender

package com.example.opengldemo;

import android.content.Context;
import android.opengl.GLES20;

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

public class FboRender {

    private Context context;
    private FloatBuffer fragmentBuffer;
    private FloatBuffer vertexBuffer;

    private int program;

    private int vPosition;
    private int fPosition;
    private int textureid;
    private int sampler;
    private int vboId;

    //顶点坐标
    private final float[] vertexData = {
            -1f, -1f,
            1f, -1f,
            -1f, 1f,
            1f, 1f
    };

    //纹理坐标
    private final float[] fragmentData = {
            0f, 1f,
            1f, 1f,
            0f, 0f,
            1f, 0f
    };

    public FboRender(Context context) {
        this.context = context;
        fragmentBuffer = ByteBuffer.allocateDirect(fragmentData.length * 4)
                .order(ByteOrder.nativeOrder())
                .asFloatBuffer()
                .put(fragmentData);
        fragmentBuffer.position(0);

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

    public void onCreate(){
        String vertexSource = GShaderUtil.getRawResource(context, R.raw.vertex_shader);
        String fragmentSource = GShaderUtil.getRawResource(context, R.raw.fragment_shader);
        program = GShaderUtil.createProgram(vertexSource, fragmentSource);
        //顶点坐标
        vPosition = GLES20.glGetAttribLocation(program, "v_Position");
        //纹理坐标
        fPosition = GLES20.glGetAttribLocation(program, "f_Position");
        sampler = GLES20.glGetUniformLocation(program,"sTexture");

        int [] vbos = new int[1];
        GLES20.glGenBuffers(1, vbos, 0);
        vboId = vbos[0];
        //绑定
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vboId);
        //分配内存
        GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER, vertexData.length*4 + fragmentData.length*4,
                null,GLES20. GL_STATIC_DRAW);
        //缓存到显存
        GLES20.glBufferSubData(GLES20.GL_ARRAY_BUFFER, 0, vertexData.length * 4, vertexBuffer);
        GLES20.glBufferSubData(GLES20.GL_ARRAY_BUFFER, vertexData.length * 4, fragmentData.length*4,
                fragmentBuffer);
        //解绑
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
    }

    public void onChange(int width,int height){
        GLES20.glViewport(0,0,width,height);
    }

    public void onDraw(int textureId){
        //清屏
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
        //使用颜色清屏
        GLES20.glClearColor(1.0f, 0.0f, 0.0f, 1.0f);

        //使用program
        GLES20.glUseProgram(program);
        //绑定纹理id
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);

        //绑定VBO
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vboId);

        //使用顶点坐标
        GLES20.glEnableVertexAttribArray(vPosition);
        //传0 从VBO中取值
        GLES20.glVertexAttribPointer(vPosition, 2, GLES20.GL_FLOAT, false, 8, 0);

        GLES20.glEnableVertexAttribArray(fPosition);

        //VBO
        GLES20.glVertexAttribPointer(fPosition, 2, GLES20.GL_FLOAT, false, 8,
                vertexData.length * 4);

        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
        //解绑
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);

        //解绑VBO
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
    }
}

修改一下窗口大小

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
        <item name="android:windowNoTitle">true</item>
        <item name="android:windowFullscreen">true</item>
    </style>

</resources>

纹理坐标系 / FBO纹理坐标系(OpenGL)