问题保存比窗口大的openGL FBO [英] problem saving openGL FBO larger than window

问题描述

我正在渲染到OpenGL屏幕外帧缓冲对象中，并喜欢将其另存为图像.请注意， FBO 大于显示尺寸.我可以渲染到屏幕外的缓冲区中并将其用作纹理，这可以正常工作.我可以使用偏移量将较大的纹理滚动"通过显示，这使我确信，我可以渲染到比窗口更大的上下文中.

I'm rendering into an OpenGL offscreen framebuffer object and like to save it as an image. Note that the FBO is larger than the display size. I can render into the offscreen buffer and use it as texture, which works. I can "scroll" this larger texture through the display using an offset, which makes me confident, that I render into a larger context than the window.

如果我将屏幕外缓冲区保存到图像文件中，则始终会被裁剪.保存的代码片段为:

If I save the offscreen buffer to an image file it always gets cropped. The code fragment for saving is:

void ofFBOTexture::saveImage(string fileName) { 
    glReadBuffer(GL_COLOR_ATTACHMENT0_EXT); 
    // get the raw buffer from ofImage
    unsigned char* pixels = imageSaver.getPixels();
    glReadPixels(0, 0, 1024, 1024, GL_RGB, GL_UNSIGNED_BYTE, pixels); 

    imageSaver.saveImage(fileName); 
} 

请注意，已裁剪图像内容，正确保存了可见部分(这意味着像素格式，GL_RGB问题等没有错误)，但是剩余空间填充了一种颜色.

Please note, that the image content is cropped, the visible part is saved correctly (which means no error in pixel formats, GL_RGB issues etc.), but the remaining space is filled with one color.

所以，我的问题是-我在做什么错了?

So, my question is - what am I doing wrong?

推荐答案

最后，我解决了这个问题.

Finally I solved the issue.

我必须激活fbo才能保存其内容:

I have to activate the fbo for saving its contents:

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo);
// save code
...
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

，而仅通过

为glReadPixels选择fbo

while only selecting the fbo for glReadPixels via

glReadBuffer(GL_COLOR_ATTACHMENT0_EXT);

不够.

(所有其他经过纠正和测试的事物，例如视口大小，缓冲区的宽度和高度，图像纹理等)

(All other things where correct and tested, eg. viewport sizes, width and height of buffer, image texture etc.)

这篇关于问题保存比窗口大的openGL FBO的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！