我在我的 libgdx_project 中使用 FBO 渲染图像传递模糊着色器，fps 下降到 20。为啥？

Posted 2023-02-22

【中文标题】我在我的 libgdx_project 中使用 FBO 渲染图像传递模糊着色器，fps 下降到 20。为啥？

【英文标题】：I use FBO to render an image pass blur shader in my libgdx_project and the fps go down to 20.why？我在我的 libgdx_project 中使用 FBO 渲染图像传递模糊着色器，fps 下降到 20。为什么？

【发布时间】：2014-09-29 07:09:35

【问题描述】：

我使用 FBO 渲染图像通道模糊着色器，然后 fps 下降到 20。为什么？当我在没有FBO的情况下直接通过x轴方向模糊它时没关系。当我只使用FBO恢复图像并将其绘制到屏幕时也可以。有什么我需要注意的吗？任何帮助都会很棒！谢谢。 这是我的代码：

private static final int FB_SIZE = 200;
public SpriteBatch batch;
protected ShaderProgram mShaderA;
protected ShaderProgram mShaderB;
protected Mesh mMeshA;
protected Mesh mMeshB;
RenderSurface  blurTargetB;
RenderSurface  blurTargetC;
Texture texture;
public void init() 
    texture = new Texture(
            Gdx.files.internal("mainMenuBack.png"));
    texture.setFilter(TextureFilter.Linear, TextureFilter.Linear);
    texture.setWrap(TextureWrap.ClampToEdge, TextureWrap.ClampToEdge);
    blurTargetB = new RenderSurface(Format.RGBA4444, 1080, 1920, true);
    blurTargetC = new RenderSurface(Format.RGBA4444, 1080, 1920, true);
    if (mMeshA != null)
        mMeshA.dispose();
    mMeshA = new Mesh(true, 4, 4, new VertexAttribute(Usage.Position, 2,
            ShaderProgram.POSITION_ATTRIBUTE), new VertexAttribute(
            Usage.TextureCoordinates, 2, ShaderProgram.TEXCOORD_ATTRIBUTE
                    + "0"));

    mMeshA.setVertices(new float[]  -1f, -1f, 0, 1, 1f, -1f, 1, 1, 1f, 1f,
            1, 0, -1f, 1f, 0, 0 );

    if (mMeshB != null)
        mMeshB.dispose();
    mMeshB = new Mesh(true, 4, 4, new VertexAttribute(Usage.Position, 2,
            ShaderProgram.POSITION_ATTRIBUTE), new VertexAttribute(
            Usage.TextureCoordinates, 2, ShaderProgram.TEXCOORD_ATTRIBUTE
                    + "1"));
    mMeshB.setVertices(new float[]  -1f, -1f, 0, 1, 1f, -1f, 1, 1, 1f, 1f,
            1, 0, -1f, 1f, 0, 0 );



public BlurRenderer() 
    mShaderA = createXBlurShader();
    mShaderB = createYBlurShader();
    init();
    batch=new SpriteBatch();



public void render() 
    drawAToB();
    drawBToC();
    drawCToSceen();




public void drawAToB() 
    blurTargetB.begin(GL20.GL_COLOR_BUFFER_BIT);

    batch.setShader(mShaderA);

    batch.begin();

    batch.draw(texture, 0,0,1080,1920);
    batch.flush();
    blurTargetB.end();


public void drawBToC() 
    blurTargetC.begin(GL20.GL_COLOR_BUFFER_BIT);

    batch.draw( blurTargetB.getTexture(), 0, 0);
    batch.flush();
    blurTargetC.end();


public void dispose() 
    mMeshA.dispose();
    mMeshB.dispose();

public void drawCToSceen() 
    batch.draw( blurTargetC.getTexture(), 0, 0);
    batch.end();


public ShaderProgram createXBlurShader() 
    String vertexShader = "attribute vec4 " + ShaderProgram.POSITION_ATTRIBUTE + ";\n" //
        + "attribute vec4 " + ShaderProgram.COLOR_ATTRIBUTE + ";\n" //
        + "attribute vec2 " + ShaderProgram.TEXCOORD_ATTRIBUTE + "0;\n" //
        + "uniform float uBlurBufferSize;\n" // 1 / Size of the blur
        + "uniform mat4 u_projTrans;\n" //
        + "varying vec4 v_color;\n" //
        + "varying vec2 v_texCoords;\n" //
        + "varying vec2 vBlurTexCoords[5];\n" // output texture
        + "\n" //
        + "void main()\n" //
        + "\n" //
        + "   v_color = " + ShaderProgram.COLOR_ATTRIBUTE + ";\n" //
        + "   v_texCoords = " + ShaderProgram.TEXCOORD_ATTRIBUTE + "0;\n" //
            + " vBlurTexCoords[0] = v_texCoords + vec2(-2.0 * uBlurBufferSize, 0.0);\n"
            + " vBlurTexCoords[1] = v_texCoords + vec2(-1.0 * uBlurBufferSize, 0.0);\n"
            + " vBlurTexCoords[2] = v_texCoords;\n"
            + " vBlurTexCoords[3] = v_texCoords + vec2( 1.0 * uBlurBufferSize, 0.0);\n"
            + " vBlurTexCoords[4] = v_texCoords + vec2( 2.0 * uBlurBufferSize, 0.0);\n"
        + "   gl_Position =  u_projTrans * " + ShaderProgram.POSITION_ATTRIBUTE + ";\n" //
        + "\n";
    String fragmentShader = "#ifdef GL_ES\n" //
        + "#define LOWP lowp\n" //
        + "precision mediump float;\n" //
        + "#else\n" //
        + "#define LOWP \n" //
        + "#endif\n" //
        + "varying LOWP vec4 v_color;\n" //
        + "varying vec2 v_texCoords;\n" //
        + "varying vec2 vBlurTexCoords[5];\n" // input texture coords
        + "uniform sampler2D u_texture;\n" //
        + "void main()\n"//
        + "\n" //
            + "  vec4 sum = vec4(0.0);\n"
            + "  sum += texture2D(u_texture, vBlurTexCoords[0]) * 0.164074;\n"
            + "  sum += texture2D(u_texture, vBlurTexCoords[1]) * 0.216901;\n"
            + "  sum += texture2D(u_texture, vBlurTexCoords[2]) * 0.23805;\n"
            + "  sum += texture2D(u_texture, vBlurTexCoords[3]) * 0.216901;\n"
            + "  sum += texture2D(u_texture, vBlurTexCoords[4]) * 0.164074;\n"
            + "  gl_FragColor = sum;\n"
        + "";
    ShaderProgram shader = new ShaderProgram(vertexShader, fragmentShader);
    if (shader.isCompiled() == false) 
        Gdx.app.log("ERROR", shader.getLog());
    
    return shader;

【问题讨论】：

什么是 RenderSurface，FrameBuffer 的包装器？模糊 1080x1920 图像的成本很高，尤其是在 android 上！通常，在进行高斯模糊时，您可以将屏幕缩小到宽度和高度的一半或四分之一，而不会造成太大的质量损失。这也让您可以使用更小的采样半径来获得相同的外观。

是的。没错，我目前发现这个页面可以解决我的问题。 github.com/mattdesl/lwjgl-basics/wiki/OpenGL-ES-Blurs 。非常感谢。

【参考方案1】：

模糊 1080x1920 图像的成本很高，尤其是在 Android 上！通常，在进行高斯模糊时，您可以将屏幕缩小到宽度和高度的一半或四分之一，而不会造成太大的质量损失。这也让您可以使用更小的采样半径来获得相同的外观。