【转】 《基于MFC的OpenGL编程》Part 1 A Primer

3D图形学基本概念

Perspective

Perspective refers to the angles between the lines that lend the illusion of three dimensions.

Colors and Shading

Moving beyond line drawing, we need to add color to create a solid object. Shading refers to the way the color is applied to the polygon. Shading can be of two types in OpenGL - Flat or Smooth.

Lights and Shadows

Plain solid color doesn’t offer enough realism. By applying Lighting effects we can make objects appear as they would in reality depending on their material properties and the lighting parameters. Adding a shadow further increases realism.

Texture Mapping

With Texture Mapping we can have wood grains, cloth textures, brick like textures etc instead of plain materials. This technique of applying an image to the surface of a polygon is called Texture Mapping. The image we use is called the Texture and the individual elements of the texture are called Texels.

Fog

Fog is an atmospheric effect that adds haziness to objects in a scene depending on how far the objects are from the viewer.

Blending and Transparency

Blending is the combination of colors of objects on the screen. This effect can be used for a variety of purposes. By varying the amount each object is blended with the scene we can make objects look transparent.

Anti-Aliasing

Aliasing is an effect that is visible on screen due to the fact that an image consists of discrete pixels. By carefully blending the lines with the background color we can eliminate jagged edges and give them a smooth appearance. This blending technique is called anti-aliasing.

第一个OpenGL程序

//Simple.cpp - First OpenGL Program
#include <windows.h> //Required for every Windows Program
#include <gl\glut.h> //Required for using the GLUT library     
//Perform OpenGL Initialization here
void SetupRC()
{
    //Set the background clearing color to blue
     glClearColor(0.0f,0.0f,1.0f,1.0f);//设置背景色为蓝色
}
//The drawing callback function
void RenderScene()
{
    //Clear the color buffer
     glClear(GL_COLOR_BUFFER_BIT);
    //Flush the rendering pipeline
     glFlush();
}
void main()
{
    //Choose the display mode settings
     glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);//初始化显示模式(单缓冲,RGB)
    //Create the Window
     glutCreateWindow("Simple");//创建窗口
    //Set the RenderScsne function as the display callback
     glutDisplayFunc(RenderScene);//绘制回调函数，当窗口需要绘制时，GLUT会调用此函数
    //Initialize OpenGL
     SetupRC();//初始化OpenGL
    //Start the GLUT framework
     glutMainLoop();//开始消息循环
}