OpenGL中的FBO如何使用模板缓冲区

FBO常用框架

一般需求只有color buffer，depth buffer，前者一般用纹理，后者一般用rbo。标准程序如下：// 创建
// frame buffer object
glGenFramebuffers（1, &fboId）;
glBindFramebuffer（GL_FRAMEBUFFER, fboId）; // color buffer with texture object
glGenTextures（1, &color_rboId）;
glBindTexture（GL_TEXTURE_2D, color_rboId）;
glTexImage2D（GL_TEXTURE_2D, 0, GL_RGBA, targetWidth, targetHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0）;
glTexParameterf（GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST）;
glTexParameterf（GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR）;
glTexParameterf（GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT）;
glTexParameterf（GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT）; // depth buffer with render buffer object
glGenRenderbuffers（1, &depth_rboId）;
glBindRenderbuffer（GL_RENDERBUFFER, depth_rboId）;
glRenderbufferStorage（GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, targetWidth, targetHeight）;

// Attach color buffer to FBO
glFramebufferTexture2D（GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, color_rboId, 0）;

//Attach depth buffer to FBO
glFramebufferRenderbuffer（GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depth_rboId）;

//Also attach as a stencil
glFramebufferRenderbuffer（GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, depth_stencil_rb）;// 删除
if （fboId ！= 0）
{
glDeleteFramebuffers（1, &fboId）;
fboId = 0;
} if （depth_rboId ！= 0）
{
glDeleteRenderbuffers（1, &depth_rboId）;
depth_rboId = 0;
}

if （color_rboId）
{
glDeleteTextures（1, &color_rboId）;
color_rboId = 0;
}

FBO中如何增加stencil buffer

正常人都会认为stencil buffer 跟depth buffer类似，于是乎写出一套类似depth buffer的框架：// 创建stencil buffer以RBO形式
glGenRenderbuffers（1, &stencil_rboId）;
glBindRenderbuffer（GL_RENDERBUFFER, stencil_rboId）;
glRenderbufferStorage（GL_RENDERBUFFER, GL_STENCIL_INDEX, targetWidth, targetHeight）;

// 关联stencil buffer 和FBO
glFramebufferRenderbuffer（GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, stencil_rboId）;

// 删除stencil buffer
glDeleteRenderbuffers（1, &stencil_rboId）;但实际测试，发现stencil buffer根本不起作用，下面是一个测试函数：void stencilRenderTest（）
{
GLdouble dRadius = 0.1; // Initial radius of spiral
GLdouble dAngle; // Looping variable
float x = 100;
float y = 100;
float rsize = 25; // Clear blue window
glClearColor（0.0f, 0.0f, 1.0f, 0.0f）; // Use 0 for clear stencil, enable stencil test
glClearStencil（0.0f）;
glEnable（GL_STENCIL_TEST）; // Clear color and stencil buffer
glClear（GL_COLOR_BUFFER_BIT | GL_STENCIL_BUFFER_BIT）; // All drawing commands fail the stencil test, and are not
// drawn, but increment the value in the stencil buffer.
glStencilFunc（GL_NEVER, 0x0, 0x0）;
glStencilOp（GL_INCR, GL_INCR, GL_INCR）; // Spiral pattern will create stencil pattern
// Draw the spiral pattern with white lines. We
// make the lines white to demonstrate that the
// stencil function prevents them from being drawn
glColor3f（1.0f, 1.0f, 1.0f）;
glBegin（GL_LINE_STRIP）;
for（dAngle = 0; dAngle < 400.0; dAngle += 0.1）
{
glVertex2d（dRadius * cos（dAngle）, dRadius * sin（dAngle））;
dRadius *= 1.002;
}
glEnd（）; // Now, allow drawing, except where the stencil pattern is 0x1
// and do not make any further changes to the stencil buffer
glStencilFunc（GL_NOTEQUAL, 0x1, 0x1）;
glStencilOp（GL_KEEP, GL_KEEP, GL_KEEP）; // Now draw red bouncing square
// （x and y） are modified by a timer function
glColor3f（1.0f, 0.0f, 0.0f）;
glRectf（x, y, x + rsize, y - rsize）;}stencil正确时，结果显示是一个蓝色背景，红色小矩形块，矩形内部可以看到圆弧，下图右。stencil不正确结果是蓝色背景同心圆环以及一个矩形红色块，图左。 相关阅读：Ubuntu 13.04 安装 OpenGL http://www.linuxidc.com/Linux/2013-05/84815.htmOpenGL三维球体数据生成与绘制【附源码】 http://www.linuxidc.com/Linux/2013-04/83235.htmUbuntu下OpenGL编程基础解析 http://www.linuxidc.com/Linux/2013-03/81675.htm如何在Ubuntu使用eclipse for c++配置OpenGL http://www.linuxidc.com/Linux/2012-11/74191.htm《OpenGL超级宝典》学习笔记 http://www.linuxidc.com/Linux/2013-10/91414.htm