OpenGL 帧缓冲区渲染到纹理不起作用

Question

我正在尝试使用帧缓冲区来使用 Java 和 JOGL 创建发光效果，但我遇到了问题。目前，我的目标是将带有照明纹理的宇宙飞船模型渲染到帧缓冲区纹理，然后将帧缓冲区纹理绘制到三角形扇形四边形。我正在使用 OpenGL 2.1 和/或 2.0 运行 这是我用于生成帧缓冲区及其纹理的代码：

private int createFrameBuffer(GL2GL3 gl) {
    _frameBufferTextureId = GLHelper.makeTextureBuffer(gl, GL2GL3.GL_RGBA, _width / 2, _height / 2, 0, GL2GL3.GL_RGBA,
            GL2GL3.GL_UNSIGNED_BYTE, GL2GL3.GL_TEXTURE_MIN_FILTER, GL2GL3.GL_TEXTURE_MIN_FILTER, GL2GL3.GL_REPEAT, null);
    int frameBufferId = GLHelper.makeFrameBuffer(gl, _frameBufferTextureId, _width / 2, _height / 2);
    return frameBufferId;
}

public static int makeTextureBuffer(GL2GL3 gl, int glEnumInternalFormat, int width, int height, int border,
        int glEnumPixelFormat, int glEnumPixelType, int glEnumMinFilter, int glEnumMagFilter, int glEnumWrapMode,
        File textureFile) {
    ByteBuffer textureDataBuffer = null;
    if (textureFile != null) {
        String filePath = textureFile.getPath();
        String extension = filePath.substring(filePath.lastIndexOf('.') + 1, filePath.length());
        TextureData textureData = null;
        try {
            textureData = TextureIO.newTextureData(gl.getGLProfile(), textureFile, false, extension);
        } catch (IOException e) {
            throw new RuntimeException("Error reading texture");
        }
        textureDataBuffer = getProperlyFormattedBuffer(textureData);
    }
    IntBuffer texture = IntBuffer.allocate(1);
    gl.glGenTextures(1, texture);
    gl.glBindTexture(GL2GL3.GL_TEXTURE_2D, texture.get(0));
    gl.glTexParameteri(GL2GL3.GL_TEXTURE_2D, GL2GL3.GL_TEXTURE_MIN_FILTER, glEnumMinFilter);
    gl.glTexParameteri(GL2GL3.GL_TEXTURE_2D, GL2GL3.GL_TEXTURE_MAG_FILTER, glEnumMagFilter);
    gl.glTexParameteri(GL2GL3.GL_TEXTURE_2D, GL2GL3.GL_TEXTURE_WRAP_S, glEnumWrapMode);
    gl.glTexParameteri(GL2GL3.GL_TEXTURE_2D, GL2GL3.GL_TEXTURE_WRAP_T, glEnumWrapMode);
    gl.glTexImage2D(GL2GL3.GL_TEXTURE_2D, 0, glEnumInternalFormat, width, height, border, glEnumPixelFormat, glEnumPixelType,
            textureDataBuffer);
    gl.glBindTexture(GL2GL3.GL_TEXTURE_2D, 0);
    return texture.get(0);
}

public static int makeFrameBuffer(GL2GL3 gl, int textureBufferId, int width, int height) {
    IntBuffer frameBuffer = IntBuffer.allocate(1);
    gl.glGenFramebuffers(1, frameBuffer);
    gl.glBindFramebuffer(GL2GL3.GL_FRAMEBUFFER, frameBuffer.get(0));
    gl.glFramebufferTexture2D(GL2GL3.GL_FRAMEBUFFER, GL2GL3.GL_COLOR_ATTACHMENT0, GL2GL3.GL_TEXTURE_2D, textureBufferId, 0);
    verifyFrameBuffer(gl);
    gl.glBindFramebuffer(GL2GL3.GL_FRAMEBUFFER, 0);
    return frameBuffer.get(0);
}

private void drawTextureQuad(GL2GL3 gl) {
    _glowShader.bind(gl);
    int textureLocation = _glowShader.getUniformFields().getIlluminationTextureLocation();
    gl.glUniform1i(textureLocation, 0);
    gl.glActiveTexture(GL2GL3.GL_TEXTURE0);
    gl.glBindTexture(GL2GL3.GL_TEXTURE_2D, _frameBufferTextureId);

    int vertexLocation = _glowShader.getAttributeFields().getVertexLocation();
    gl.glBindBuffer(GL2GL3.GL_ARRAY_BUFFER, _textureQuadId);
    gl.glVertexAttribPointer(vertexLocation, 3, GL2GL3.GL_FLOAT, false, 0, 0);
    gl.glEnableVertexAttribArray(vertexLocation);

    int textureCoordLocation = _glowShader.getAttributeFields().getVertexTextureCoordinateLocation();
    gl.glBindBuffer(GL2GL3.GL_ARRAY_BUFFER, _textureQuadCoordsId);
    gl.glVertexAttribPointer(textureCoordLocation, 2, GL2GL3.GL_FLOAT, false, 0, 0);
    gl.glEnableVertexAttribArray(textureCoordLocation);

    gl.glDrawArrays(GL2GL3.GL_TRIANGLE_FAN, 0, 4);
    _glowShader.unbind(gl);
}

在我的渲染循环中，我正在执行以下操作：

_glowShader.bind(gl);// bind my Shader object.
gl.glUniformMatrix4fv(_glowShader.getUniformFields().getProjectionMatrixLocation(), 1, true, _projectionMatrix.getBuffer());
gl.glUniformMatrix4fv(_glowShader.getUniformFields().getModelViewMatrixLocation(), 1, true, _modelViewMat.getBuffer());
gl.glBindFramebuffer(GL.GL_FRAMEBUFFER, _framebufferId);
gl.glDrawBuffers(1, _frameBufferAttachmentss); //contains GL_COLOR_ATTACHMENT0
gl.glViewport(0, 0, _width / 2, _height / 2); // same size as texture
_spaceship.draw(gl, _glowShader);// draw method in my ModelObject class
gl.glBindFramebuffer(GL.GL_FRAMEBUFFER, 0);
_glowShader.unbind(gl);

drawTextureQuad(gl);

当我运行此命令时，我的四边形按应有的方式绘制，但是纹理是全黑的。当我注释掉渲染循环中的任何帧缓冲区绑定时，模型会按应有的方式渲染，因此我知道我的着色器代码没有任何问题。当我用从文件加载的另一个纹理替换 _frameBufferTextureId 时，该纹理已正确绘制，因此我知道我的纹理坐标正在工作，而且我的着色器代码也是正确的。不过，每当我绑定帧缓冲区时，我都不会得到任何我期望的东西。我还在验证我的帧缓冲区，它是 GL_FRAMEBUFFER_COMPLETE。

我在 stackoverflow 上阅读了无数的教程和帖子，但我一生都无法弄清楚我做错了什么。任何帮助都会很棒！谢谢。

Answer 1

正如 Bethor 指出的，我将 GL_TEXTURE_MIN_FILTER 两次传递给我的 makeTextureBuffer 方法。这是对 glTexParameteri() 调用的解析：

gl.glTexParameteri(GL2GL3.GL_TEXTURE_2D, GL2GL3.GL_TEXTURE_MIN_FILTER, GL2GL2.GL_TEXTURE_MIN_FILTER);
gl.glTexParameteri(GL2GL3.GL_TEXTURE_2D, GL2GL3.GL_TEXTURE_MAG_FILTER, GL2GL2.GL_TEXTURE_MIN_FILTER);

这当然是没有意义的。更改我的调用以传入 GL_LINEAR 修复了所有问题。