我正在尝试在iPhone上使用OpenGL ES创建一个离屏渲染缓冲区。我已经像这样创建了缓冲区:
glGenFramebuffersOES(1, &offscreenFramebuffer);
glBindFramebufferOES(GL_FRAMEBUFFER_OES, offscreenFramebuffer);
glGenRenderbuffersOES(1, &offscreenRenderbuffer);
glBindRenderbufferOES(GL_RENDERBUFFER_OES, offscreenRenderbuffer);
glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_RENDERBUFFER_OES, offscreenRenderbuffer);
但我对如何呈现存储感到困惑。苹果的文档说要使用EAGLContext renderBufferStorage:fromDrawable:方法,但这似乎仅适用于一个渲染缓冲区(主显示缓冲区)。如果我使用普通的OpenGL函数glRenderBufferStorageOES,则似乎无法显示。以下是代码:
// this is in the initialization section:
glRenderbufferStorageOES(GL_RENDERBUFFER_OES, GL_RGB8_OES, backingWidth, backingHeight);
// and this is when I'm trying to draw to it and display it:
glBindFramebufferOES(GL_FRAMEBUFFER_OES, offscreenFramebuffer);
GLfloat vc[] = {
0.0f, 0.0f, 0.0f,
10.0f, 10.0f, 10.0f,
0.0f, 0.0f, 0.0f,
-10.0f, -10.0f, -10.0f,
};
glLoadIdentity();
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, vc);
glDrawArrays(GL_LINES, 0, 4);
glDisableClientState(GL_VERTEX_ARRAY);
glBindRenderbufferOES(GL_RENDERBUFFER_OES, offscreenRenderbuffer);
[context presentRenderbuffer:GL_RENDERBUFFER_OES];
按照这种方式做,屏幕上不会显示任何内容。 但是,如果我将对 "offscreen...Buffer" 的引用替换为使用 renderBufferStorage 方法创建的缓冲区,它就可以正常工作。
有什么建议吗?