笔记：OpenGL SuperBible - First Program

// Include the "sb6.h" header file#include "sb6.h"// Derive my_application from sb6::applicationclass my_application : public sb6::application {public:    // Our rendering function    void render(double currentTime) {        // Simply clear the window with red        static const GLfloat red[] = { 1.0f, 0.0f, 0.0f, 1.0f };        glClearBufferfv(GL_COLOR, 0, red);    }};// Our one and only instance of DECLARE_MAINDECLARE_MAIN(my_application);

注解：

1、函数 glClearBufferfv 原型：

void glClearBufferfv(GLenum buffer,GLint drawBuffer,const GLfloat * value); 

glClearBufferfv() tells OpenGL to clear the buffer specifiedby the first parameter (in this caseGL_COLOR) to the value specified in itsthird parameter. The second parameter, drawBuffer, is used when there are multiple output buffers that could be cleared. Because we’re only using one here and drawBufferis a zero-based index, we’ll just set it to zero in this example. 

2、currentTime：

the number ofseconds since the application was started, and we can use it to create asimple animation. 

The following example use it to change colour for clearing the window:

Animating color over time:

 // Our rendering functionvoid render(double currentTime) {const GLfloat color[] = { (float)sin(currentTime) * 0.5f + 0.5f, (float)cos(currentTime) * 0.5f + 0.5f,                                  0.0f, 1.0f };        glClearBufferfv(GL_COLOR, 0, color);}

REFERENCE: OpenGL SuperBible 6th