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
#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
}