OpenGL ES 2.0 渲染到纹理 [英] OpenGL ES 2.0 render to texture

问题描述

我正在尝试使用 OpenGL ES 2.0 渲染到纹理，但我似乎无法让它工作.

I'm trying to render to a texture using OpenGL ES 2.0, but I can't seem to make it work.

我是这样进行的:

    struct RenderTexture
    {
        GLuint framebuffer;
        GLuint tex;
        GLint old_fbo;


        RenderTexture(GLuint width, GLuint height)
        {
            glGetIntegerv(GL_FRAMEBUFFER_BINDING, &old_fbo);

            glGenFramebuffers(1, &framebuffer);
            glGenTextures(1, &tex);

            glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
            glBindTexture(GL_TEXTURE_2D, tex);
            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 
                         width, height, 0, GL_RGBA, 
                         GL_UNSIGNED_BYTE, NULL);
            glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, 
                                   tex, 0);

            glClearColor(1, 0, 0, 1);
            glClear(GL_COLOR_BUFFER_BIT);

            GLuint status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
            if (status != GL_FRAMEBUFFER_COMPLETE) {
                cout << status << endl; // this is not called
            }

            glBindFramebuffer(GL_FRAMEBUFFER, old_fbo);
        }

        void begin()
        {
            glGetIntegerv(GL_FRAMEBUFFER_BINDING, &old_fbo);
            glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
        }

        void end()
        {
            glBindFramebuffer(GL_FRAMEBUFFER, old_fbo);
        }
    };

但是当我尝试在其上绘制并使用生成的纹理时，纹理被绘制为全黑.

But when I try drawing on it and using the resulting texture, the texture is drawn as totally black.

如果我只是不将绘图代码包装在 render_tex->begin(); 和 render_tex->end(); 中，一切都会正确绘制，让我相信问题与上面的代码无关.

If I just don't wrap the drawing code in render_tex->begin(); and render_tex->end();, everything draws correctly, leading me to believe that the problem is isolated to the code above.

推荐答案

这已经有一段时间了，但正如我在评论中所写的，请确保您正在初始化 2 的幂纹理.

This has been a while, but as I wrote in the comments, be sure you're initializing a power of 2 texture.

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