Opengl es: Render to Texture via Frame Buffer is r

问题:

am trying to implement a motion blur effect in my android game.

After a lot of research I found that the best way to do that is to save the previous frame as a texture using the Frame Buffer Object and render it on top of the current frame. So seeing some nice tutorials on how to do something like that I ended up with this code which basically render my scene on the texture and then draws the texture to the default framebuffer.

But the texture has only one color ,like when i have a green explotion texture is only green
I believe this is a problem with the render buffer or the texture parameters

here is my code

int[] fb, depthRb, renderTex; 
int texW = 1024; 
int texH = 1024; 
IntBuffer texBuffer;
int[] buf = new int[texW * texH];
GL11ExtensionPack gl11ep ;
void setup(GL10 gl)
{
    fb = new int[1];
    depthRb = new int[1];
    renderTex = new int[1];
    // generate
    ((GL11ExtensionPack)gl).glGenFramebuffersOES(1, fb, 0);
    ((GL11ExtensionPack)gl).glGenRenderbuffersOES(1, depthRb, 0); // the depth buffer

    gl.glEnable(GL10.GL_TEXTURE_2D);
    gl.glGenTextures(1, renderTex, 0);// generate texture
    gl.glBindTexture(GL10.GL_TEXTURE_2D, renderTex[0]);

    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_CLAMP_TO_EDGE);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_CLAMP_TO_EDGE);

    texBuffer = ByteBuffer.allocateDirect(buf.length*4).order(ByteOrder.nativeOrder()).asIntBuffer();

     gl.glTexEnvf(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE,GL10.GL_MODULATE);

    gl.glTexImage2D(GL10.GL_TEXTURE_2D, 0, GL10.GL_RGBA, texW, texH, 0, GL10.GL_RGBA, GL10.GL_UNSIGNED_SHORT_4_4_4_4, texBuffer);

    // create render buffer and bind 16-bit depth buffer
    ((GL11ExtensionPack)gl).glBindRenderbufferOES(GL11ExtensionPack.GL_RENDERBUFFER_OES, depthRb[0]);
    ((GL11ExtensionPack)gl).glRenderbufferStorageOES(GL11ExtensionPack.GL_RENDERBUFFER_OES, GL11ExtensionPack.GL_DEPTH_COMPONENT16, texW, texH);

    gl.glDisable(GL10.GL_TEXTURE_2D);

}

boolean RenderStart(GL10 gl)
{
    // Bind the framebuffer
    ((GL11ExtensionPack)gl).glBindFramebufferOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, fb[0]);

    // specify texture as color attachment
    ((GL11ExtensionPack)gl).glFramebufferTexture2DOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, GL11ExtensionPack.GL_COLOR_ATTACHMENT0_OES, GL10.GL_TEXTURE_2D, renderTex[0], 0);

    // attach render buffer as depth buffer
    ((GL11ExtensionPack)gl).glFramebufferRenderbufferOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, GL11ExtensionPack.GL_DEPTH_ATTACHMENT_OES, GL11ExtensionPack.GL_RENDERBUFFER_OES, depthRb[0]);

    int error = gl.glGetError();
    if (error != GL10.GL_NO_ERROR) {
        Log.w("err", "Background Load GLError: " + error+"      ");
    }
    int status = ((GL11ExtensionPack)gl).glCheckFramebufferStatusOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES);
    if (status != GL11ExtensionPack.GL_FRAMEBUFFER_COMPLETE_OES)
    {
        Tools.con("ret");
        return true;
    }
    gl.glClear( GL10.GL_DEPTH_BUFFER_BIT | GL10.GL_COLOR_BUFFER_BIT);
    return true;
}

void RenderEnd(GL10 gl)
{
    ((GL11ExtensionPack)gl).glBindFramebufferOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, 0);

    gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);

    gl.glEnable(GL10.GL_TEXTURE_2D);
    gl.glBindTexture(GL10.GL_TEXTURE_2D, renderTex[0]);
    gl.glColor4f(1,1,1,1);
    ((GL11Ext) gl).glDrawTexfOES(0, 0, -2,1024,1024);
    gl.glDisable(GL10.GL_TEXTURE_2D);

}


public void onDrawFrame(GL10 gl)
    {

    this.RenderStart(gl);
    render(gl);//render scene
    this.RenderEnd(gl);
    }

public void onSurfaceCreated(GL10 gl, EGLConfig config)
    {
       ...
       setup(gl);
    }

回答1:

try to replace

gl.glTexEnvf(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE,GL10.GL_MODULATE); 

with

gl.glTexEnvf(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE,GL10.GL_REPLACE);