ios - GLKView，如何 blitFrameBuffer，如果可能的话

Question

这是我的设置，宽度和高度是GLKView的边界*缩放

private func initFrameBuffer() -> GLuint {
    var framebuffer_id: GLuint = 0
    glGenFramebuffers(1, &framebuffer_id)
    glBindFramebuffer(GLenum(GL_FRAMEBUFFER), framebuffer_id)
    return framebuffer_id
}

private func initRenderBuffer(_ width: GLsizei, _ height: GLsizei) -> GLuint {
    var renderBuffer_id: GLuint = 0
    glGenRenderbuffers(1, &renderBuffer_id)
    glBindRenderbuffer(GLenum(GL_RENDERBUFFER), renderBuffer_id)
    glRenderbufferStorage(GLenum(GL_RENDERBUFFER), GLenum(GL_RGBA8), width, height)
    glFramebufferRenderbuffer(GLenum(GL_FRAMEBUFFER), GLenum(GL_COLOR_ATTACHMENT0), GLenum(GL_RENDERBUFFER), renderBuffer_id)
    return renderBuffer_id
}

func blitz() {
    glBindFramebuffer(GLenum(GL_FRAMEBUFFER), frameBuffer)
    bindDrawable()
    glBlitFramebuffer(0, 0, width, height, 0, 0, width, height, GLbitfield(GL_COLOR_BUFFER_BIT), GLenum(GL_LINEAR))
}

我在draw(_ rect)中调用blitz()，但没有任何反应，所以当我检查错误时，它给了我一个GL_INVALID_OPERATION.

我还尝试获取 ios FBO 的 id 并手动绑定(bind)它来代替调用 bindDrawble()，这也失败了。

Answer 1

glBlitFramebuffer 从当前绑定(bind)的 GL_READ_FRAMEBUFFER 复制到当前绑定(bind)的 GL_DRAW_FRAMEBUFFER。绑定(bind)到目标 GL_FRAMEBUFFER 是将 FBO 同时绑定(bind)到 both GL_READ_FRAMEBUFFER 和 GL_DRAW_FRAMEBUFFER 的快捷方式，所以你的blit是从framebuffer到framebuffer，这是不允许的。