将屏幕外帧缓冲纹理渲染为主帧缓冲

我正在尝试使用一个帧缓冲对象，我无法控制它的设置方式。所以我正在创建一个具有深度的屏幕外fbo来绘制我的纹理。然后将其绘制到主帧缓冲区。我可以使用 OpenGL 分析器从资源中看到纹理，但我似乎无法让它绘制到主帧缓冲区。

这是我的代码

GLsizei glSizeWidthEquiv = width;
        GLsizei glSizeHeightEquiv = height;
        GLint originalFramebuffer;
        glGetIntegerv(GL_FRAMEBUFFER_BINDING, &originalFramebuffer);
        if(fbo == 0){
            glGenFramebuffers(1, &fbo);
        }
        glBindFramebuffer(GL_FRAMEBUFFER, fbo);
        //Creating texture for framebuffer
        if(texColorBuffer == 0){
            glGenTextures(1, &texColorBuffer);
        }
        glBindTexture([outTex target], texColorBuffer);
        //Having it as null means the texture's data will be created dynamically
        //Using RGBA since the alpha layer is going to be needed
        glTexImage2D([outTex target], 0, GL_RGBA_FLOAT16_APPLE, glSizeWidthEquiv, glSizeHeightEquiv, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
        glTexParameteri([outTex target], GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri([outTex target], GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        //Attach texture to framebuffer
        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, [outTex target], texColorBuffer, 0);
        //Creating render buffer
        if(renderBuffer == 0){
            glGenRenderbuffers(1, &renderBuffer);
        }
        glBindRenderbuffer(GL_RENDERBUFFER, renderBuffer);
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, glSizeWidthEquiv, glSizeHeightEquiv);
        //Binding the renderbuffer to the framebuffer
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, renderBuffer);
        //Check framebuffer
        if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE){
            NSLog(@"Framebuffer incomplete noobn");
        }else{
            NSLog(@"Framebuffer COMPLETE!n");
        }
        //Start to use the frame buffer
        glBindFramebuffer(GL_FRAMEBUFFER, fbo);
        glViewport(0, 0, glSizeWidthEquiv, glSizeHeightEquiv);
        //cleaning texture: cleaning code here
        //initating glTex0
        glActiveTexture(GL_TEXTURE0);
        //setting up texture stuff
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
                    glClearColor(0, 0, 0, 1);
        glDisable(GL_CULL_FACE);
        glColor3f(1,0,0);

        glBegin(GL_QUADS);
        //box 1 in front
        glVertex3f(0, 0, 0);
        glVertex3f(500, 0, 0);
        glVertex3f(500, 500, 0);
        glVertex3f(0, 500, 0);
        //box 2 at the back
        glColor3f(0, 1, 0);
        glVertex3f(-250, -250, 50);
        glVertex3f(250, -250, 50);
        glVertex3f(250, 250, 50);
        glVertex3f(-250, 250, 50);
        glEnd();
        glFogCoordf(9);
        //End of framebuffer usage
        glBindFramebuffer(GL_FRAMEBUFFER, originalFramebuffer);
        glViewport(0, 0, (GLsizei)[outTex width], (GLsizei)[outTex height]);
        [self glGetError];
        glActiveTexture(GL_TEXTURE0);
        glBindTexture([outTex target], texColorBuffer);
        glCopyTexSubImage2D([outTex target], 0, 0, 0, 0, 0, glSizeWidthEquiv, glSizeHeightEquiv);

        glFlush();

程序的这一部分位于渲染部分，我在初始化时将fbo，renderBuffer和texColorBuffer设置为0，以防止它生成新的缓冲区。

所以本质上我正在创建缓冲区，直到它完成，然后重新绑定我创建的 fbo 来绘制我的形状。切换回原始 fbo 并尝试绘制它。

这里使用的[outTex目标]是GL_TEXTURE_RECTANGLE_ARB。

这是我在OpenGL分析器的纹理部分中的内容：http://img.photobucket.com/albums/v442/ardo/ScreenShot2013-10-27at112742PM.png

@GMasucci

我不完全确定这是否是创建 sscce 的正确方法，但这里有一个易于复制粘贴的代码，包括库、GLUT 和 OpenGL。这里使用的代码是从 www.videotutorialsrock.com 照明课程中捎带而来的，因此我有一个类似的环境。

#include <iostream>
#include <stdlib.h>
#ifdef __APPLE__
#include <OpenGL/OpenGL.h>
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif
using namespace std;
GLuint fbo,texColorBuffer,renderBuffer;
float  camMatrix [4][4];
//Initializes 3D rendering
void initRendering() {
    glEnable(GL_DEPTH_TEST);
}
//Called when the window is resized
void handleResize(int w, int h) {
    glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0, (double)w / (double)h, 1.0, 200.0);
}
//Draws the 3D scene
void drawScene() {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0.0f, 0.0f, -8.0f);

if(fbo == 0){
    glGenFramebuffers(1, &fbo);
}
glBindFramebuffer(GL_FRAMEBUFFER, fbo);
if(texColorBuffer == 0){
    glGenTextures(1, &texColorBuffer);
}
glBindTexture(GL_TEXTURE_2D, texColorBuffer);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 400, 400, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texColorBuffer, 0);
if(renderBuffer == 0){
    glGenRenderbuffers(1, &renderBuffer);
}
glBindRenderbuffer(GL_RENDERBUFFER, renderBuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, 400, 400);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, renderBuffer);
if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE){
    printf("Error in framebuffer completeness n");
}
glBindFramebuffer(GL_FRAMEBUFFER, fbo);
glViewport(0, 0, 400, 400);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glActiveTexture(GL_TEXTURE0);
glBegin(GL_QUADS);
glColor3f(1,0,0);
glVertex3f(0, 0, 0);
glVertex3f(200, 0, 0);
glVertex3f(200, 200, 0);
glVertex3f(0, 200, 0);
glColor3f(0, 1, 0);
glVertex3f(-100, -100, -1);
glVertex3f(100, -100, -1);
glVertex3f(100, 100, -1);
glVertex3f(-100, 100, -1);
glEnd();
glFogCoordf(0);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glViewport(0, 0, (GLsizei)400, (GLsizei)400);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texColorBuffer);
glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, 400, 400);
glutSwapBuffers();
}
void update(int value) {
glutPostRedisplay();
glutTimerFunc(25, update, 0);
}
int main(int argc, char** argv) {
//Initialize GLUT
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(400, 400);
//set fbo,texBuffer and renderbuffer to 0
fbo = 0;
texColorBuffer = 0;
renderBuffer = 0;
//Create the window
glutCreateWindow("Lighting - videotutorialsrock.com");
initRendering();
//Set handler functions
glutDisplayFunc(drawScene);
glutReshapeFunc(handleResize);
glutTimerFunc(25, update, 0); //Add a timer
glutMainLoop();
return 0;
}