ios - iOS渲染到纹理:为什么清晰

Question

我正在尝试使用此帖子将屏幕渲染
http://www.idevgames.com/forums/thread-1785-post-54500.html#pid54500

首先，我初始化FBO。

glGenTextures(1, &tex);
glBindTexture(GL_TEXTURE_2D, tex);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 512, 512, 0,  GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glBindTexture(GL_TEXTURE_2D, 0);
glGenFramebuffersOES(1, &fbo);
glBindFramebufferOES(GL_FRAMEBUFFER_OES, fbo);
glFramebufferTexture2DOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_TEXTURE_2D, tex, 0);

GLenum status = glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES); 
if (status != GL_FRAMEBUFFER_COMPLETE_OES) { 
    NSLog(@"failed to make complete framebuffer object %x", status);
    exit(-1);
}

然后画我的质地

GLint oldFBO, oldViewPort[4];
glGetIntegerv(GL_FRAMEBUFFER_BINDING_OES, &oldFBO);
glGetIntegerv(GL_VIEWPORT, oldViewPort);
glBindTexture(GL_TEXTURE_2D, 0);
glBindFramebufferOES(GL_FRAMEBUFFER_OES, listFrameBuffers[i]);
glViewport(0, 0, 512, 512);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

// draw code here
glBindFramebufferOES(GL_FRAMEBUFFER_OES, oldFBO);
glViewport(oldViewPort[0], oldViewPort[1], oldViewPort[2], oldViewPort[3]);

然后我画每个框架。

完成帧调用后，附加到framebuffer的glSwapBuffers纹理变得清晰
(但是当我每次在glSwapBuffers之后绘制到帧缓冲区时，一切都很好)。

Answer 1

至此，任务完成。
我只是将绘制代码更改为此

GLint oldFBO, oldViewPort[4];
glGetIntegerv(GL_FRAMEBUFFER_BINDING_OES, &oldFBO);
glGetIntegerv(GL_VIEWPORT, oldViewPort);
glBindTexture(GL_TEXTURE_2D, 0);
glBindFramebufferOES(GL_FRAMEBUFFER_OES, listFrameBuffers[i]);
glViewport(0, 0, 512, 512);
//glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // HERE
glDisable(GL_DEPTH_TEST); // AND HERE

// draw code here

glBindFramebufferOES(GL_FRAMEBUFFER_OES, oldFBO);
glViewport(oldViewPort[0], oldViewPort[1], oldViewPort[2], oldViewPort[3]);

而且有效! :)