android opengl fbo模式

本文主要是介绍android opengl fbo模式，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

opengl 有好多o啊,还有ibo,vbo和vao,我都被搞糊涂了...

试了试fbo和vbo。fbo是挺有用的，用它实现了多线程渲染,vbo听说能提高效率

贴代码

public class GLRenderer implements GLSurfaceView.Renderer {private int programId;

    //vertexData和textureVertexData数组基本固定不变
    private final float[] vertexData = {1f, -1f, 0f,
            -1f, -1f, 0f,
            1f, 1f, 0f,
            -1f, 1f, 0f
    };
    private FloatBuffer vertexBuffer;
    private FloatBuffer textureVertexBuffer;

    private int aPositionHandle;
    private int uTextureSamplerHandle;
    private int aTextureCoordHandle;

    private int[] textures;
    private int[] frameBuffers;
    private int[] vertexBuffers;

    private Context context;
    private Bitmap bitmap;


    public GLRenderer(Context context){this.context = context;
        bitmap = BitmapFactory.decodeResource(context.getResources(),R.drawable.plane_image);

        final float[] textureVertexData = {1f, 0f,
                0f, 0f,
                1f, 1f,
                0f, 1f
        };
        vertexBuffer = ByteBuffer.allocateDirect(vertexData.length * 4).order(ByteOrder.nativeOrder()).asFloatBuffer().put(vertexData);
        vertexBuffer.position(0);

        textureVertexBuffer = ByteBuffer.allocateDirect(textureVertexData.length * 4).order(ByteOrder.nativeOrder()).asFloatBuffer().put(textureVertexData);
        textureVertexBuffer.position(0);
    }@Override
    public void onSurfaceCreated(GL10 gl10, EGLConfig eglConfig) {String vertexShader = ShaderUtils.readRawTextFile(context, R.raw.bitmap_vertext_shader);
        String fragmentShader = ShaderUtils.readRawTextFile(context, R.raw.bitmap_fragment_sharder);

        programId = ShaderUtils.createProgram(vertexShader, fragmentShader);
        aPositionHandle = GLES20.glGetAttribLocation(programId, "aPosition");
        uTextureSamplerHandle = GLES20.glGetUniformLocation(programId, "sTexture");
        aTextureCoordHandle = GLES20.glGetAttribLocation(programId, "aTexCoord");

        //初始化vbo
        vertexBuffers = new int[1];
        GLES20.glGenBuffers(1,vertexBuffers,0);
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vertexBuffers[0]);
        GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER, vertexData.length*4, vertexBuffer,GLES20.GL_STATIC_DRAW);
        GLES20.glBufferSubData(GLES20.GL_ARRAY_BUFFER,0,vertexData.length*4,vertexBuffer);
        //初始化fbo
        frameBuffers = new int[1];
        GLES20.glGenFramebuffers(1, frameBuffers, 0);
        GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, frameBuffers[0]);

        //初始化纹理
        textures = new int[2];
        GLES20.glGenTextures(2, textures, 0);

        //给fbo用的纹理，不是fbo纹理
        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textures[0]);
        GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER,
                GLES20.GL_NEAREST);
        GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER,
                GLES20.GL_LINEAR);
        GLUtils.texImage2D(GLES20.GL_TEXTURE_2D,0,GLES20.GL_RGBA,bitmap,0);

        GLES20.glUseProgram(programId);
        //绑定vbo
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vertexBuffers[0]);
        GLES20.glEnableVertexAttribArray(aPositionHandle);
        GLES20.glVertexAttribPointer(aPositionHandle, 3, GLES20.GL_FLOAT, false,
                12, 0);
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);

        //这是原来写法，没有glBindBuffer和vertexBuffers[0]
        //GLES20.glEnableVertexAttribArray(aPositionHandle);
        //GLES20.glVertexAttribPointer(aPositionHandle, 3, GLES20.GL_FLOAT, false,12, vertexBuffer);

        GLES20.glEnableVertexAttribArray(aTextureCoordHandle);
        GLES20.glVertexAttribPointer(aTextureCoordHandle, 2, GLES20.GL_FLOAT, false, 8, textureVertexBuffer);
        //*这是关键步，当时看别人的例子就是不成功，当时对opengl理解还不深，把它移到下边就清楚了
        GLES20.glUniform1i(uTextureSamplerHandle,0);

        //初始化fbo纹理
        GLES20.glActiveTexture(GLES20.GL_TEXTURE1);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textures[1]);
        GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER,
                GLES20.GL_NEAREST);
        GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER,
                GLES20.GL_LINEAR);
        //创建一个只有宽高，没有数据的纹理
        GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_RGBA, bitmap.getWidth(), bitmap.getHeight(), 0, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, null);
        //绑定
        GLES20.glFramebufferTexture2D(GLES20.GL_FRAMEBUFFER, GLES20.GL_COLOR_ATTACHMENT0, GLES20.GL_TEXTURE_2D, textures[1], 0);


        if(GLES20.glCheckFramebufferStatus(GLES20.GL_FRAMEBUFFER) == GLES20.GL_FRAMEBUFFER_COMPLETE){}GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);
        GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);

    }@Override
    public void onSurfaceChanged(GL10 gl10, int screenWidth, int screenHeight) {//还是没用矩阵，而且数学还不好，就凑合着用吧
        int bitmapWidth = bitmap.getWidth();
        int bitmapHeight = bitmap.getHeight();
        int left,top,viewWidth,viewHeight;
        if(screenHeight > screenWidth){left = 0;
            viewWidth = screenWidth;
            viewHeight = (int)(bitmapHeight*1.0f/bitmapWidth*viewWidth);
            top = (screenHeight - viewHeight)/2;
        }else{top = 0;
            viewHeight = screenHeight;
            viewWidth = (int)(bitmapWidth*1.0f/bitmapHeight*viewHeight);
            left = (screenWidth - viewWidth)/2;
        }rect.left = left;
        rect.top = top;
        rect.right = left + viewWidth;
        rect.bottom = top + viewHeight;
    }private Rect rect = new Rect();
    @Override
    public void onDrawFrame(GL10 gl10) {//*把给fbo用的纹理传入shader里，把上边的代码可以移到这里
        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textures[0]);
        GLES20.glUniform1i(uTextureSamplerHandle,0);

        GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, frameBuffers[0]);
        GLES20.glClear(GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);
        GLES20.glViewport(0, 0, bitmap.getWidth(), bitmap.getHeight());
        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
        //GLES20.glDrawElements()听说适合绘制复杂图形
        //fbo用完后换回显示窗口
        GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);

        //*渲染fbo纹理，这次把fbo纹理传入shader内
        GLES20.glActiveTexture(GLES20.GL_TEXTURE1);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textures[1]);
        GLES20.glUniform1i(uTextureSamplerHandle,1);

        GLES20.glClear(GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);
        GLES20.glViewport(rect.left, rect.top, rect.width(), rect.height());
        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
    }
}

配合GLSurfaceView使用

bitmap_fragment_sharder

precision mediump float;
varying vec2 vTexCoord;
uniform sampler2D sTexture;
void main() {gl_FragColor = texture2D(sTexture, vTexCoord);//
}

bitmap_vertext_sharder

attribute vec4 aPosition;
attribute vec2 aTexCoord;
varying vec2 vTexCoord;
void main() {vTexCoord = vec2(aTexCoord.x,1.0-aTexCoord.y);gl_Position = aPosition;
}

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