ios - 渲染到纹理 : always black texture

Question

我正在尝试渲染到纹理并随后使用该纹理，但由于某种原因它不起作用。

如 Apple 所述 documentation ,

首先我分配 fbo 渲染到纹理..

glGenFramebuffers(1, &read_framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, read_framebuffer);

然后我创建纹理并将其附加到那个 fbo..

glActiveTexture(GL_TEXTURE0);
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8_OES, 64, 64, 0, GL_RGBA,
             GL_UNSIGNED_BYTE, NULL);
glBindRenderbuffer(GL_RENDERBUFFER, 0);
glBindTexture(GL_TEXTURE_2D, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
                       texture, 0);

然后创建用于绘图的 fbo..

glGenFramebuffers(1, &draw_framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, draw_framebuffer);
glGenRenderbuffers(1, &_colorRenderBuffer);
glBindRenderbuffer(GL_RENDERBUFFER, _colorRenderBuffer);
[_context renderbufferStorage:GL_RENDERBUFFER fromDrawable:_eaglLayer];
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, _colorRenderBuffer);

稍后在渲染循环部分..

glBindFramebuffer(GL_FRAMEBUFFER, read_framebuffer);

(...off-screen drawing the scene here...)

glBindFramebuffer(GL_FRAMEBUFFER, draw_framebuffer);

绑定(bind)应该包含我的离屏渲染图像的纹理..

glBindTexture(GL_TEXTURE_2D, texture);

(..draw the scene with texture applied here...)

但是，由于某种原因，纹理始终是黑色的。我是否遗漏了什么？

Answer 1

在 glTexImage2D 中将 GL_RGBA8_OES 替换为 GL_RGBA。我可以看到您从苹果文档中获取了这些参数。(无评论。)无论如何，正如@prideout 指出的那样，关于您的问题的评论，您应该始终检查帧缓冲区状态。在您的情况下，它返回了 GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT。