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我目前正在尝试制作一个使用多个 opengl es 视口（即分屏）的 ios 应用程序。这是我的做法：

// Create default framebuffer object. The backing will be allocated for the current layer in -resizeFromLayer
    glGenFramebuffersOES(1, &defaultFramebuffer);
    glGenRenderbuffersOES(1, &colorRenderbuffer);
    glBindFramebufferOES(GL_FRAMEBUFFER_OES, defaultFramebuffer);
    glBindRenderbufferOES(GL_RENDERBUFFER_OES, colorRenderbuffer);
    glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_RENDERBUFFER_OES, colorRenderbuffer);

// Replace the implementation of this method to do your own custom drawing
const GLfloat squareVertices[] = {
  -0.5f, -0.5f,
  0.5f,  -0.5f,
  -0.5f,  0.5f,
  0.5f,   0.5f,
};
const GLubyte squareColors[] = {
  255, 255,   0, 255,
  0,   255, 255, 255,
  0,     0,   0,   0,
  255,   0, 255, 255,
 };

[EAGLContext setCurrentContext:context];

glBindFramebufferOES(GL_FRAMEBUFFER_OES, defaultFramebuffer);
glViewport(0, backingHeight/2, backingWidth/2, backingHeight/2);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrthof(-1.0f, 1.0f, -1.5f, 1.5f, -1.0f, 1.0f);
glMatrixMode(GL_MODELVIEW);
glRotatef(3.0f, 0.0f, 0.0f, 1.0f);

glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);

glVertexPointer(2, GL_FLOAT, 0, squareVertices);
glEnableClientState(GL_VERTEX_ARRAY);
glColorPointer(4, GL_UNSIGNED_BYTE, 0, squareColors);
glEnableClientState(GL_COLOR_ARRAY);

glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

glBindRenderbufferOES(GL_RENDERBUFFER_OES, colorRenderbuffer);
// equivalent to glutswapBuffers()
[context presentRenderbuffer:GL_RENDERBUFFER_OES];

/*********************SECOND VIEW*******/
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glBindFramebufferOES(GL_FRAMEBUFFER_OES, defaultFramebuffer);
glViewport(backingWidth/2, 0, backingWidth/2, backingHeight/2);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrthof(-1.0f, 1.0f, -1.5f, 1.5f, -1.0f, 1.0f);
glMatrixMode(GL_MODELVIEW);
glRotatef(3.0f, 0.0f, 0.0f, 1.0f);

glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);

glVertexPointer(2, GL_FLOAT, 0, squareVertices);
glEnableClientState(GL_VERTEX_ARRAY);
glColorPointer(4, GL_UNSIGNED_BYTE, 0, squareColors);
glEnableClientState(GL_COLOR_ARRAY);

glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

glBindRenderbufferOES(GL_RENDERBUFFER_OES, colorRenderbuffer);
[context presentRenderbuffer:GL_RENDERBUFFER_OES];
/*********************END***************/

glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_COLOR_ARRAY);
  1. 在模拟器上，只出现第二个视口（在这种情况下，屏幕右下角有一个旋转的立方体）。而在设备上它们都出现但闪烁......（左上和右下）
  2. glRotatef 被应用两次，但我只想或任何其他转换应用一次。

我想要的只是将同一场景显示两次。基本上我正在尝试模拟让 2 个摄像机观看同一件事，并将其显示在屏幕上。显然，我做错了什么，最好有 2 个单独的帧缓冲区和渲染缓冲区，还是有更简单的方法来实现这一点？

4

1 回答 1

2

问题是这一行：

/*********************SECOND VIEW*******/
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_FRAMEBUFFER);

glClear 不受视口影响，如果要部分清除，则需要使用剪刀测试或模板缓冲区。

请参阅glClear的文档。

于 2012-07-05T23:10:27.783 回答